- Published on
Emergency and Acute Medicine – Isopropanol poisoning
Isopropanol is a central nervous system depressant that is two to three times more potent than ethanol. It is rapidly absorbed after ingestion and is metabolized by alcohol dehydrogenase to acetone, which is also a CNS depressant. Unlike other toxic alcohols, isopropanol is ketogenic but does not cause a significant metabolic acidosis. Acetone is eliminated by the lungs and kidneys. The half-life of isopropanol ranges from 3 to 16 hours, while acetone has a longer half-life of 7.5 to 26 hours. Concomitant ethanol ingestion prolongs the half-life of isopropanol but not acetone.
Isopropanol is a clear, colorless, volatile liquid with a faint acetone odor and bitter taste, commonly found as 70% rubbing alcohol. It is present in many household and industrial products including disinfectants, hand sanitizers, solvents, window cleaners, paint removers, detergents, antifreeze, and toiletries. The typical adult patient is a chronic alcoholic who ingests isopropanol after depleting ethanol supplies. Dermal, inhalational, and rectal exposures can also cause systemic toxicity. Accidental ingestions are common in young children.
Symptoms usually develop within 30 to 60 minutes of exposure. Neurologic manifestations include lethargy, inebriation, vertigo, ataxia, headache, weakness, respiratory depression, coma, and apnea, without the initial excitatory phase seen with ethanol. Gastrointestinal findings include nausea, vomiting, abdominal pain, gastritis, and hematemesis. Cardiovascular effects include hypotension, tachycardia, myocardial depression, and peripheral vasodilation. Pulmonary findings include respiratory depression and hemorrhagic tracheobronchitis. Skin and eye exposure may cause irritation or chemical burns.
Diagnosis is based on history of exposure and the characteristic odor of isopropanol or acetone on the breath. Laboratory evaluation typically shows ketosis without significant acidosis unless end-organ hypoperfusion is present. Hypoglycemia may occur, particularly in children. Acetone can falsely elevate serum creatinine, which normalizes as acetone is metabolized. Urinalysis shows ketones, and an elevated osmolar gap is common. Coma is associated with serum isopropanol levels greater than 150 mg/dL. Imaging is guided by clinical findings, with chest radiography used to assess for aspiration and head CT considered for possible trauma.
Management is primarily supportive, with attention to airway protection, breathing, and circulation. Hypotension is treated with intravenous fluids and vasopressors if needed. There is no specific antidote, and treatment with ethanol or fomepizole is contraindicated. Activated charcoal may be considered if coingestants are suspected. Skin and eye exposures require copious irrigation. Hemodialysis effectively removes isopropanol and acetone and is reserved for patients with refractory hypotension, severe toxicity, or serum levels greater than 400 mg/dL.
Patients with moderate to severe toxicity, including altered mental status or hypotension, require hospital admission. Asymptomatic or mildly intoxicated patients may be observed for 2 to 4 hours and discharged if symptoms resolve. Referral for alcohol detoxification or psychiatric evaluation is recommended for intentional ingestions.
Supportive care remains the cornerstone of treatment, and a key pitfall is inappropriate use of ethanol or fomepizole, which should be avoided in isopropanol poisoning.
Isopropanol is a central nervous system depressant that is two to three times more potent than ethanol. It is rapidly absorbed after ingestion and is metabolized by alcohol dehydrogenase to acetone, which is also a CNS depressant. Unlike other toxic alcohols, isopropanol is ketogenic but does not cause a significant metabolic acidosis. Acetone is eliminated by the lungs and kidneys. The half-life of isopropanol ranges from 3 to 16 hours, while acetone has a longer half-life of 7.5 to 26 hours. Concomitant ethanol ingestion prolongs the half-life of isopropanol but not acetone.
Isopropanol is a clear, colorless, volatile liquid with a faint acetone odor and bitter taste, commonly found as 70% rubbing alcohol. It is present in many household and industrial products including disinfectants, hand sanitizers, solvents, window cleaners, paint removers, detergents, antifreeze, and toiletries. The typical adult patient is a chronic alcoholic who ingests isopropanol after depleting ethanol supplies. Dermal, inhalational, and rectal exposures can also cause systemic toxicity. Accidental ingestions are common in young children.
Symptoms usually develop within 30 to 60 minutes of exposure. Neurologic manifestations include lethargy, inebriation, vertigo, ataxia, headache, weakness, respiratory depression, coma, and apnea, without the initial excitatory phase seen with ethanol. Gastrointestinal findings include nausea, vomiting, abdominal pain, gastritis, and hematemesis. Cardiovascular effects include hypotension, tachycardia, myocardial depression, and peripheral vasodilation. Pulmonary findings include respiratory depression and hemorrhagic tracheobronchitis. Skin and eye exposure may cause irritation or chemical burns.
Diagnosis is based on history of exposure and the characteristic odor of isopropanol or acetone on the breath. Laboratory evaluation typically shows ketosis without significant acidosis unless end-organ hypoperfusion is present. Hypoglycemia may occur, particularly in children. Acetone can falsely elevate serum creatinine, which normalizes as acetone is metabolized. Urinalysis shows ketones, and an elevated osmolar gap is common. Coma is associated with serum isopropanol levels greater than 150 mg/dL. Imaging is guided by clinical findings, with chest radiography used to assess for aspiration and head CT considered for possible trauma.
Management is primarily supportive, with attention to airway protection, breathing, and circulation. Hypotension is treated with intravenous fluids and vasopressors if needed. There is no specific antidote, and treatment with ethanol or fomepizole is contraindicated. Activated charcoal may be considered if coingestants are suspected. Skin and eye exposures require copious irrigation. Hemodialysis effectively removes isopropanol and acetone and is reserved for patients with refractory hypotension, severe toxicity, or serum levels greater than 400 mg/dL.
Patients with moderate to severe toxicity, including altered mental status or hypotension, require hospital admission. Asymptomatic or mildly intoxicated patients may be observed for 2 to 4 hours and discharged if symptoms resolve. Referral for alcohol detoxification or psychiatric evaluation is recommended for intentional ingestions.
Supportive care remains the cornerstone of treatment, and a key pitfall is inappropriate use of ethanol or fomepizole, which should be avoided in isopropanol poisoning.
- Published on
Emergency and Acute Medicine – Isopropanol poisoning
Isopropanol is a central nervous system depressant that is two to three times more potent than ethanol. It is rapidly absorbed after ingestion and is metabolized by alcohol dehydrogenase to acetone, which is also a CNS depressant. Unlike other toxic alcohols, isopropanol is ketogenic but does not cause a significant metabolic acidosis. Acetone is eliminated by the lungs and kidneys. The half-life of isopropanol ranges from 3 to 16 hours, while acetone has a longer half-life of 7.5 to 26 hours. Concomitant ethanol ingestion prolongs the half-life of isopropanol but not acetone.
Isopropanol is a clear, colorless, volatile liquid with a faint acetone odor and bitter taste, commonly found as 70% rubbing alcohol. It is present in many household and industrial products including disinfectants, hand sanitizers, solvents, window cleaners, paint removers, detergents, antifreeze, and toiletries. The typical adult patient is a chronic alcoholic who ingests isopropanol after depleting ethanol supplies. Dermal, inhalational, and rectal exposures can also cause systemic toxicity. Accidental ingestions are common in young children.
Symptoms usually develop within 30 to 60 minutes of exposure. Neurologic manifestations include lethargy, inebriation, vertigo, ataxia, headache, weakness, respiratory depression, coma, and apnea, without the initial excitatory phase seen with ethanol. Gastrointestinal findings include nausea, vomiting, abdominal pain, gastritis, and hematemesis. Cardiovascular effects include hypotension, tachycardia, myocardial depression, and peripheral vasodilation. Pulmonary findings include respiratory depression and hemorrhagic tracheobronchitis. Skin and eye exposure may cause irritation or chemical burns.
Diagnosis is based on history of exposure and the characteristic odor of isopropanol or acetone on the breath. Laboratory evaluation typically shows ketosis without significant acidosis unless end-organ hypoperfusion is present. Hypoglycemia may occur, particularly in children. Acetone can falsely elevate serum creatinine, which normalizes as acetone is metabolized. Urinalysis shows ketones, and an elevated osmolar gap is common. Coma is associated with serum isopropanol levels greater than 150 mg/dL. Imaging is guided by clinical findings, with chest radiography used to assess for aspiration and head CT considered for possible trauma.
Management is primarily supportive, with attention to airway protection, breathing, and circulation. Hypotension is treated with intravenous fluids and vasopressors if needed. There is no specific antidote, and treatment with ethanol or fomepizole is contraindicated. Activated charcoal may be considered if coingestants are suspected. Skin and eye exposures require copious irrigation. Hemodialysis effectively removes isopropanol and acetone and is reserved for patients with refractory hypotension, severe toxicity, or serum levels greater than 400 mg/dL.
Patients with moderate to severe toxicity, including altered mental status or hypotension, require hospital admission. Asymptomatic or mildly intoxicated patients may be observed for 2 to 4 hours and discharged if symptoms resolve. Referral for alcohol detoxification or psychiatric evaluation is recommended for intentional ingestions.
Supportive care remains the cornerstone of treatment, and a key pitfall is inappropriate use of ethanol or fomepizole, which should be avoided in isopropanol poisoning.
Isopropanol is a central nervous system depressant that is two to three times more potent than ethanol. It is rapidly absorbed after ingestion and is metabolized by alcohol dehydrogenase to acetone, which is also a CNS depressant. Unlike other toxic alcohols, isopropanol is ketogenic but does not cause a significant metabolic acidosis. Acetone is eliminated by the lungs and kidneys. The half-life of isopropanol ranges from 3 to 16 hours, while acetone has a longer half-life of 7.5 to 26 hours. Concomitant ethanol ingestion prolongs the half-life of isopropanol but not acetone.
Isopropanol is a clear, colorless, volatile liquid with a faint acetone odor and bitter taste, commonly found as 70% rubbing alcohol. It is present in many household and industrial products including disinfectants, hand sanitizers, solvents, window cleaners, paint removers, detergents, antifreeze, and toiletries. The typical adult patient is a chronic alcoholic who ingests isopropanol after depleting ethanol supplies. Dermal, inhalational, and rectal exposures can also cause systemic toxicity. Accidental ingestions are common in young children.
Symptoms usually develop within 30 to 60 minutes of exposure. Neurologic manifestations include lethargy, inebriation, vertigo, ataxia, headache, weakness, respiratory depression, coma, and apnea, without the initial excitatory phase seen with ethanol. Gastrointestinal findings include nausea, vomiting, abdominal pain, gastritis, and hematemesis. Cardiovascular effects include hypotension, tachycardia, myocardial depression, and peripheral vasodilation. Pulmonary findings include respiratory depression and hemorrhagic tracheobronchitis. Skin and eye exposure may cause irritation or chemical burns.
Diagnosis is based on history of exposure and the characteristic odor of isopropanol or acetone on the breath. Laboratory evaluation typically shows ketosis without significant acidosis unless end-organ hypoperfusion is present. Hypoglycemia may occur, particularly in children. Acetone can falsely elevate serum creatinine, which normalizes as acetone is metabolized. Urinalysis shows ketones, and an elevated osmolar gap is common. Coma is associated with serum isopropanol levels greater than 150 mg/dL. Imaging is guided by clinical findings, with chest radiography used to assess for aspiration and head CT considered for possible trauma.
Management is primarily supportive, with attention to airway protection, breathing, and circulation. Hypotension is treated with intravenous fluids and vasopressors if needed. There is no specific antidote, and treatment with ethanol or fomepizole is contraindicated. Activated charcoal may be considered if coingestants are suspected. Skin and eye exposures require copious irrigation. Hemodialysis effectively removes isopropanol and acetone and is reserved for patients with refractory hypotension, severe toxicity, or serum levels greater than 400 mg/dL.
Patients with moderate to severe toxicity, including altered mental status or hypotension, require hospital admission. Asymptomatic or mildly intoxicated patients may be observed for 2 to 4 hours and discharged if symptoms resolve. Referral for alcohol detoxification or psychiatric evaluation is recommended for intentional ingestions.
Supportive care remains the cornerstone of treatment, and a key pitfall is inappropriate use of ethanol or fomepizole, which should be avoided in isopropanol poisoning.
- Published on
Emergency and Acute Medicine – Kawasaki disease
Kawasaki disease is an acute, self-limited inflammatory illness involving multiple organ systems and is the leading cause of acquired heart disease in children in developed countries. It is a medium-vessel vasculitis with particular predilection for the coronary arteries. Acute cardiac complications include myocarditis, pericarditis, and coronary artery aneurysms, which may later progress to stenosis or thrombosis; giant aneurysms carry a risk of rupture. The disease progresses through three stages: an acute phase lasting 1–2 weeks characterized by fever and systemic inflammation; a subacute phase extending to approximately 4 weeks marked by desquamation, thrombocytosis, and the highest risk of sudden death from coronary involvement; and a convalescent phase lasting 6–8 weeks during which symptoms resolve and inflammatory markers normalize.
Epidemiologically, 80% of cases occur in children younger than 4 years, with a peak incidence between 1 and 2 years of age. The disease is rare in infants younger than 3 months, though adult cases have been reported. Males are affected more often than females, and children of Asian descent have the highest incidence, suggesting a genetic predisposition. Delayed diagnosis, prolonged fever, male sex, extremes of age, elevated inflammatory markers, anemia, hypoalbuminemia, and abnormal initial echocardiography increase the risk of coronary artery aneurysm formation. Approximately 10–15% of patients are resistant to standard therapy.
The etiology remains unknown, but the disease is thought to represent an abnormal immune response to an infectious trigger in genetically susceptible individuals. Seasonal clustering and epidemic patterns support this hypothesis, with increased incidence in winter and early spring.
Diagnosis is clinical. Classic Kawasaki disease is defined by fever lasting at least 5 days in combination with four of five features: bilateral nonexudative conjunctival injection, oral mucosal changes (such as strawberry tongue or cracked lips), polymorphous rash, extremity changes (erythema, edema, or desquamation), and cervical lymphadenopathy greater than 1.5 cm. Incomplete or atypical Kawasaki disease should be suspected in children with prolonged fever and fewer criteria accompanied by elevated ESR or CRP and supportive laboratory findings such as anemia, hypoalbuminemia, elevated ALT, leukocytosis, thrombocytosis after day 7, or sterile pyuria.
Clinical presentation typically includes abrupt onset of high, spiking fever persisting longer than 5 days. Children often appear irritable and ill. Ocular findings include conjunctivitis without exudate and photophobia. Oral findings include erythema, fissured lips, and strawberry tongue. Skin findings are variable and usually involve the trunk, while extremity changes include painful edema and erythema followed later by desquamation of the fingers and toes. Gastrointestinal symptoms such as vomiting, diarrhea, abdominal pain, and gallbladder hydrops may occur. Cardiac manifestations include myocarditis, pericarditis, heart failure, and, later, coronary artery aneurysms.
Evaluation requires a high index of suspicion in any febrile child with rash. Laboratory findings typically include elevated ESR and CRP, leukocytosis with left shift, normocytic anemia, thrombocytosis in the subacute phase, sterile pyuria, and mild transaminase elevation. Blood, urine, CSF, and throat cultures are negative. Echocardiography is essential to assess coronary artery involvement and should be performed at diagnosis, at 2–3 weeks, and again at 6–8 weeks. ECG may be indicated if myocardial involvement is suspected.
The differential diagnosis includes viral illnesses such as adenovirus, measles, Epstein–Barr virus, and influenza; bacterial infections such as scarlet fever, staphylococcal scalded skin syndrome, and rickettsial disease; immune-mediated conditions including Stevens–Johnson syndrome and serum sickness; and other vasculitides or connective tissue diseases.
Management focuses on early treatment to prevent cardiac complications. All patients meeting diagnostic criteria should be admitted. Initial therapy consists of intravenous immunoglobulin and high-dose aspirin, ideally within the first 10 days of illness, which reduces the incidence of coronary artery aneurysms from approximately 20–25% to 2–4%. Cardiology consultation is required, and myocardial infarction is treated similarly to adults if it occurs.
First-line treatment includes IVIG at 2 g/kg administered over 10–12 hours, with repeat dosing for persistent or recrudescent fever. High-dose aspirin is given during the acute phase for anti-inflammatory effect, followed by low-dose aspirin for antiplatelet therapy during the convalescent period. Patients who fail two doses of IVIG may require corticosteroids or other immunomodulatory therapies such as infliximab or cyclosporine.
All patients diagnosed with Kawasaki disease require hospitalization, while nontoxic children who do not meet diagnostic criteria may be discharged with close follow-up. Long-term cardiology follow-up is mandatory for monitoring coronary artery involvement.
Early recognition and treatment are critical, as prompt IVIG and aspirin therapy prevent coronary aneurysm formation in the vast majority of patients. Kawasaki disease should be strongly considered in children with persistent fever and repeated emergency visits, and incomplete presentations must not be overlooked.
Kawasaki disease is an acute, self-limited inflammatory illness involving multiple organ systems and is the leading cause of acquired heart disease in children in developed countries. It is a medium-vessel vasculitis with particular predilection for the coronary arteries. Acute cardiac complications include myocarditis, pericarditis, and coronary artery aneurysms, which may later progress to stenosis or thrombosis; giant aneurysms carry a risk of rupture. The disease progresses through three stages: an acute phase lasting 1–2 weeks characterized by fever and systemic inflammation; a subacute phase extending to approximately 4 weeks marked by desquamation, thrombocytosis, and the highest risk of sudden death from coronary involvement; and a convalescent phase lasting 6–8 weeks during which symptoms resolve and inflammatory markers normalize.
Epidemiologically, 80% of cases occur in children younger than 4 years, with a peak incidence between 1 and 2 years of age. The disease is rare in infants younger than 3 months, though adult cases have been reported. Males are affected more often than females, and children of Asian descent have the highest incidence, suggesting a genetic predisposition. Delayed diagnosis, prolonged fever, male sex, extremes of age, elevated inflammatory markers, anemia, hypoalbuminemia, and abnormal initial echocardiography increase the risk of coronary artery aneurysm formation. Approximately 10–15% of patients are resistant to standard therapy.
The etiology remains unknown, but the disease is thought to represent an abnormal immune response to an infectious trigger in genetically susceptible individuals. Seasonal clustering and epidemic patterns support this hypothesis, with increased incidence in winter and early spring.
Diagnosis is clinical. Classic Kawasaki disease is defined by fever lasting at least 5 days in combination with four of five features: bilateral nonexudative conjunctival injection, oral mucosal changes (such as strawberry tongue or cracked lips), polymorphous rash, extremity changes (erythema, edema, or desquamation), and cervical lymphadenopathy greater than 1.5 cm. Incomplete or atypical Kawasaki disease should be suspected in children with prolonged fever and fewer criteria accompanied by elevated ESR or CRP and supportive laboratory findings such as anemia, hypoalbuminemia, elevated ALT, leukocytosis, thrombocytosis after day 7, or sterile pyuria.
Clinical presentation typically includes abrupt onset of high, spiking fever persisting longer than 5 days. Children often appear irritable and ill. Ocular findings include conjunctivitis without exudate and photophobia. Oral findings include erythema, fissured lips, and strawberry tongue. Skin findings are variable and usually involve the trunk, while extremity changes include painful edema and erythema followed later by desquamation of the fingers and toes. Gastrointestinal symptoms such as vomiting, diarrhea, abdominal pain, and gallbladder hydrops may occur. Cardiac manifestations include myocarditis, pericarditis, heart failure, and, later, coronary artery aneurysms.
Evaluation requires a high index of suspicion in any febrile child with rash. Laboratory findings typically include elevated ESR and CRP, leukocytosis with left shift, normocytic anemia, thrombocytosis in the subacute phase, sterile pyuria, and mild transaminase elevation. Blood, urine, CSF, and throat cultures are negative. Echocardiography is essential to assess coronary artery involvement and should be performed at diagnosis, at 2–3 weeks, and again at 6–8 weeks. ECG may be indicated if myocardial involvement is suspected.
The differential diagnosis includes viral illnesses such as adenovirus, measles, Epstein–Barr virus, and influenza; bacterial infections such as scarlet fever, staphylococcal scalded skin syndrome, and rickettsial disease; immune-mediated conditions including Stevens–Johnson syndrome and serum sickness; and other vasculitides or connective tissue diseases.
Management focuses on early treatment to prevent cardiac complications. All patients meeting diagnostic criteria should be admitted. Initial therapy consists of intravenous immunoglobulin and high-dose aspirin, ideally within the first 10 days of illness, which reduces the incidence of coronary artery aneurysms from approximately 20–25% to 2–4%. Cardiology consultation is required, and myocardial infarction is treated similarly to adults if it occurs.
First-line treatment includes IVIG at 2 g/kg administered over 10–12 hours, with repeat dosing for persistent or recrudescent fever. High-dose aspirin is given during the acute phase for anti-inflammatory effect, followed by low-dose aspirin for antiplatelet therapy during the convalescent period. Patients who fail two doses of IVIG may require corticosteroids or other immunomodulatory therapies such as infliximab or cyclosporine.
All patients diagnosed with Kawasaki disease require hospitalization, while nontoxic children who do not meet diagnostic criteria may be discharged with close follow-up. Long-term cardiology follow-up is mandatory for monitoring coronary artery involvement.
Early recognition and treatment are critical, as prompt IVIG and aspirin therapy prevent coronary aneurysm formation in the vast majority of patients. Kawasaki disease should be strongly considered in children with persistent fever and repeated emergency visits, and incomplete presentations must not be overlooked.
- Published on
Emergency And Acute Medicine – Knee Dislocation
Basics Description
Knee dislocation is defined by displacement of the tibia relative to the distal femur and represents a true orthopedic emergency because of the high risk of vascular and neurologic injury. Anterior dislocation is the most common type, accounting for approximately 60% of cases, and typically results from hyperextension. Rupture of the posterior capsule may occur at 30° of hyperextension, with disruption of the posterior cruciate ligament and potential popliteal artery injury at greater degrees. Posterior dislocation usually results from a direct blow to the anterior tibia with the knee flexed, such as a dashboard injury. Medial and lateral dislocations occur from varus or valgus stress, respectively, and are associated with multiligamentous injuries.
Popliteal artery injury occurs in up to 35% of knee dislocations and is the most limb-threatening complication. Anterior dislocations commonly cause traction-related intimal injury with delayed thrombosis, whereas posterior dislocations are more likely to cause direct arterial transection and immediate thrombosis. Peroneal nerve injury is less common but clinically significant and often accompanies arterial injury, particularly in medial or rotational dislocations.
Etiology
Knee dislocations typically result from high-energy mechanisms such as motor vehicle collisions, auto–pedestrian trauma, or athletic injuries, most commonly football.
Diagnosis Signs And Symptoms
Patients may present with a grossly deformed or unstable knee, though spontaneous reduction can mask deformity. Absence of distal pulses or signs of ischemia such as pallor, paresthesia, pain, paralysis, or poikilothermia raise immediate concern for popliteal artery injury. Neurologic deficits may include decreased sensation in the first web space or inability to dorsiflex the foot. A careful history of the mechanism of injury and repeated neurovascular examinations are essential.
Essential Workup
Evaluation requires a detailed history and thorough physical examination with emphasis on vascular and neurologic status. Distal pulses should be assessed by palpation and Doppler, capillary refill documented, and ankle–brachial index calculated. Neurologic examination should assess peroneal nerve function. Repeat examinations are mandatory, especially after reduction.
Diagnosis Tests And Interpretation
AP and lateral knee radiographs are required to confirm alignment and exclude associated fractures. MRI within one week is useful for defining ligamentous injury. An ABI ≥0.9 suggests low likelihood of major arterial injury, but abnormal findings warrant further evaluation. Vascular ultrasound or arteriography should be considered when pulses are diminished, ischemic symptoms persist, or peroneal nerve injury is present.
Differential Diagnosis
Conditions to consider include tibial plateau fracture, supracondylar femoral fracture, and ligamentous or tendinous avulsion injuries.
Treatment Pre Hospital
Initial management focuses on airway, breathing, and circulation. Distal pulses and motor function must be documented. The knee should be splinted in slight flexion to minimize popliteal artery tension.
Initial Stabilization Therapy
Address ABCs, particularly in polytrauma patients. Hypotension should be corrected, as it may obscure vascular compromise. Immediate closed reduction is indicated for any evidence of limb ischemia, with early orthopedic and vascular consultation.
Ed Treatment Procedures
Closed reduction is performed using longitudinal traction with gentle realignment, avoiding pressure in the popliteal fossa. The knee is immobilized in 15–20° of flexion. Neurovascular status must be reassessed immediately after reduction and monitored frequently. IV analgesia should be provided, and surgical consultation obtained for open injuries, vascular compromise, or irreducible dislocations.
Medication
IV narcotic analgesia is first-line. Oral medications should be avoided due to the high likelihood of operative intervention.
Follow-Up Disposition
All patients with knee dislocation require admission for observation and management of potential vascular injury. Discharge from the ED is not appropriate.
Follow-Up Recommendations
Orthopedic follow-up is required for staged ligamentous repair, typically delayed until swelling subsides. Vascular surgery follow-up is necessary if popliteal artery injury is identified.
Pearls And Pitfalls
Failure to restore popliteal artery flow within 6–8 hours carries an amputation risk approaching 90%. Peroneal nerve injury has a poor prognosis for recovery. Delayed compartment syndrome may occur and requires vigilant monitoring.
Basics Description
Knee dislocation is defined by displacement of the tibia relative to the distal femur and represents a true orthopedic emergency because of the high risk of vascular and neurologic injury. Anterior dislocation is the most common type, accounting for approximately 60% of cases, and typically results from hyperextension. Rupture of the posterior capsule may occur at 30° of hyperextension, with disruption of the posterior cruciate ligament and potential popliteal artery injury at greater degrees. Posterior dislocation usually results from a direct blow to the anterior tibia with the knee flexed, such as a dashboard injury. Medial and lateral dislocations occur from varus or valgus stress, respectively, and are associated with multiligamentous injuries.
Popliteal artery injury occurs in up to 35% of knee dislocations and is the most limb-threatening complication. Anterior dislocations commonly cause traction-related intimal injury with delayed thrombosis, whereas posterior dislocations are more likely to cause direct arterial transection and immediate thrombosis. Peroneal nerve injury is less common but clinically significant and often accompanies arterial injury, particularly in medial or rotational dislocations.
Etiology
Knee dislocations typically result from high-energy mechanisms such as motor vehicle collisions, auto–pedestrian trauma, or athletic injuries, most commonly football.
Diagnosis Signs And Symptoms
Patients may present with a grossly deformed or unstable knee, though spontaneous reduction can mask deformity. Absence of distal pulses or signs of ischemia such as pallor, paresthesia, pain, paralysis, or poikilothermia raise immediate concern for popliteal artery injury. Neurologic deficits may include decreased sensation in the first web space or inability to dorsiflex the foot. A careful history of the mechanism of injury and repeated neurovascular examinations are essential.
Essential Workup
Evaluation requires a detailed history and thorough physical examination with emphasis on vascular and neurologic status. Distal pulses should be assessed by palpation and Doppler, capillary refill documented, and ankle–brachial index calculated. Neurologic examination should assess peroneal nerve function. Repeat examinations are mandatory, especially after reduction.
Diagnosis Tests And Interpretation
AP and lateral knee radiographs are required to confirm alignment and exclude associated fractures. MRI within one week is useful for defining ligamentous injury. An ABI ≥0.9 suggests low likelihood of major arterial injury, but abnormal findings warrant further evaluation. Vascular ultrasound or arteriography should be considered when pulses are diminished, ischemic symptoms persist, or peroneal nerve injury is present.
Differential Diagnosis
Conditions to consider include tibial plateau fracture, supracondylar femoral fracture, and ligamentous or tendinous avulsion injuries.
Treatment Pre Hospital
Initial management focuses on airway, breathing, and circulation. Distal pulses and motor function must be documented. The knee should be splinted in slight flexion to minimize popliteal artery tension.
Initial Stabilization Therapy
Address ABCs, particularly in polytrauma patients. Hypotension should be corrected, as it may obscure vascular compromise. Immediate closed reduction is indicated for any evidence of limb ischemia, with early orthopedic and vascular consultation.
Ed Treatment Procedures
Closed reduction is performed using longitudinal traction with gentle realignment, avoiding pressure in the popliteal fossa. The knee is immobilized in 15–20° of flexion. Neurovascular status must be reassessed immediately after reduction and monitored frequently. IV analgesia should be provided, and surgical consultation obtained for open injuries, vascular compromise, or irreducible dislocations.
Medication
IV narcotic analgesia is first-line. Oral medications should be avoided due to the high likelihood of operative intervention.
Follow-Up Disposition
All patients with knee dislocation require admission for observation and management of potential vascular injury. Discharge from the ED is not appropriate.
Follow-Up Recommendations
Orthopedic follow-up is required for staged ligamentous repair, typically delayed until swelling subsides. Vascular surgery follow-up is necessary if popliteal artery injury is identified.
Pearls And Pitfalls
Failure to restore popliteal artery flow within 6–8 hours carries an amputation risk approaching 90%. Peroneal nerve injury has a poor prognosis for recovery. Delayed compartment syndrome may occur and requires vigilant monitoring.
- Published on
Infectious Diseases and Microbiology: Gonorrhea
Basics
Description
Gonorrhea is caused by Neisseria gonorrhoeae, a gram-negative intracellular diplococcus that infects humans only. Spread occurs through direct mucosal inoculation during sexual contact or childbirth. Transmission is more efficient from men to women, and a single sexual exposure can infect up to half of female partners.
Epidemiology
Gonorrhea remains a major global public health issue and contributes substantially to morbidity, especially in developing regions. Worldwide incidence has been estimated at roughly 62 million new infections annually, with highest rates in sub-Saharan Africa, South and Southeast Asia, the Caribbean, and Latin America. In the United States, hundreds of thousands of cases were reported in 2008 with the highest rates in females aged 15–19 and males aged 20–24; reported rates were higher in African American and Hispanic populations than in White populations.
Risk Factors
Risk is increased by female sex, age under 25, prior gonorrhea or other STIs, new or multiple partners, inconsistent condom use, commercial sex work, drug use, and travel to high-prevalence countries.
General Prevention
Control relies on early detection, immediate treatment at diagnosis, and treatment of sexual partners. Partners within 60 days before symptom onset should be evaluated and treated. Delaying sexual debut, reducing partner number, and consistent condom use decrease transmission.
Etiology
Disease is due to N. gonorrhoeae, a nonmotile, non–spore-forming gram-negative diplococcus.
Commonly Associated Conditions
Coinfection with other STIs is common; Chlamydia coinfection occurs in about one-third of cases. Gonorrhea also increases susceptibility to acquiring HIV.
Diagnosis
Clinical manifestations depend on infection site, bacterial strain, host factors, sex, and coinfections. Many infections are asymptomatic in both sexes. Incubation is typically 2–7 days. In men, urethritis usually begins with dysuria followed by purulent discharge, and acute epididymitis is the most frequent complication. In women, urethritis can cause dysuria, frequency, and urgency, and cervicitis may develop with purulent discharge, cramping, dyspareunia, and postcoital or intermenstrual bleeding; symptoms often intensify around menstruation. Untreated infection can ascend, causing pelvic inflammatory disease with infertility and chronic pelvic pain. Conjunctivitis usually results from autoinoculation and can rapidly threaten vision. In neonates, infection is commonly ophthalmia neonatorum acquired during delivery; ocular prophylaxis with agents such as silver nitrate drops or tetracycline ointment is used for prevention. Disseminated gonococcal infection may present with fever, rash, tenosynovitis, and septic arthritis and can resemble an influenza-like illness without obvious mucosal symptoms, so urethral/cervical, rectal, and pharyngeal sites should be sampled.
Diagnostic Tests and Interpretation
Laboratory Studies
In symptomatic men, Gram stain of urethral discharge can show polymorphonuclear cells and gram-negative intracellular diplococci, but Gram stain performs poorly with endocervical, rectal, and pharyngeal specimens. Culture allows antimicrobial susceptibility testing and should be performed on selective media such as modified Thayer–Martin (or equivalent) with aerobic conditions and increased CO₂; rapid processing is essential because gonococci do not tolerate drying. Strains linked to dissemination may be more fastidious and harder to grow. Nucleic acid–based tests can detect N. gonorrhoeae from swabs or urine with sensitivity and specificity comparable or better than culture, but cost is higher and cross-reactivity with nonpathogenic Neisseria species can occur.
Differential Diagnosis
Urethritis can be nongonococcal due to Chlamydia, Ureaplasma, Mycoplasma genitalium, Haemophilus vaginalis, HSV, adenovirus, and others. Vaginal symptoms may reflect candidiasis, bacterial vaginosis, trichomoniasis, or noninfectious etiologies such as chemical irritation, allergy, fistula, or pregnancy-related leukorrhea. Disseminated gonococcal infection must be distinguished from meningococcemia, ecthyma gangrenosum, other bacteremias, septic arthritis from other bacteria, and reactive arthritis.
Treatment
Medications
CDC-recommended therapy has centered on cephalosporins. For uncomplicated urethral, cervical, or rectal infection, recommended single-dose options include ceftriaxone 125 mg IM, cefixime 400 mg PO, or spectinomycin 2 g IM. Pharyngeal infection is harder to eradicate and is treated with ceftriaxone 125 mg IM as the preferred regimen. Gonococcal conjunctivitis is treated with ceftriaxone 125 mg IM once, with saline eye irrigation as an optional adjunct. Disseminated infection is treated with parenteral cephalosporin-based regimens such as ceftriaxone 1 g IM/IV daily or cefotaxime/ceftizoxime 1 g IV three times daily, or spectinomycin 2 g IM twice daily; continue parenteral therapy for 24–48 hours after clinical improvement, then transition to an oral agent such as cefixime 400 mg PO twice daily to complete a total of one week. If chlamydial infection has not been excluded, provide concurrent chlamydia therapy. Fluoroquinolones are not recommended as first-line therapy in the United States because of widespread resistance.
Additional Treatment
Because Chlamydia coinfection is common, initial management should cover chlamydia (e.g., azithromycin or doxycycline) unless it has been ruled out.
Ongoing Care and Follow-Up
Patient Monitoring
A routine test-of-cure is not required after treating uncomplicated infection. If symptoms persist, obtain culture with susceptibility testing; the most common reason for apparent treatment failure is reinfection from an untreated partner.
Patient Education
Advise consistent condom use and provide instruction on correct condom use.
Complications
The most important complication is pelvic inflammatory disease from ascending infection, which can lead to tubo-ovarian abscess, pelvic peritonitis, and Fitz-Hugh–Curtis syndrome, with long-term infertility and chronic pelvic pain. In men, complications include epididymitis, periurethritis, balanitis, acute or chronic prostatitis, orchitis, seminal vasculitis, and infection of Tyson and Cowper glands. Disseminated gonococcemia is more common in women, with menstruation increasing risk, and typically causes tenosynovitis, migratory arthritis, and peripheral skin lesions that may be maculopapular or pustular; blood cultures are positive in only a minority of cases. Endocarditis and meningitis are rare in the antibiotic era.
Basics
Description
Gonorrhea is caused by Neisseria gonorrhoeae, a gram-negative intracellular diplococcus that infects humans only. Spread occurs through direct mucosal inoculation during sexual contact or childbirth. Transmission is more efficient from men to women, and a single sexual exposure can infect up to half of female partners.
Epidemiology
Gonorrhea remains a major global public health issue and contributes substantially to morbidity, especially in developing regions. Worldwide incidence has been estimated at roughly 62 million new infections annually, with highest rates in sub-Saharan Africa, South and Southeast Asia, the Caribbean, and Latin America. In the United States, hundreds of thousands of cases were reported in 2008 with the highest rates in females aged 15–19 and males aged 20–24; reported rates were higher in African American and Hispanic populations than in White populations.
Risk Factors
Risk is increased by female sex, age under 25, prior gonorrhea or other STIs, new or multiple partners, inconsistent condom use, commercial sex work, drug use, and travel to high-prevalence countries.
General Prevention
Control relies on early detection, immediate treatment at diagnosis, and treatment of sexual partners. Partners within 60 days before symptom onset should be evaluated and treated. Delaying sexual debut, reducing partner number, and consistent condom use decrease transmission.
Etiology
Disease is due to N. gonorrhoeae, a nonmotile, non–spore-forming gram-negative diplococcus.
Commonly Associated Conditions
Coinfection with other STIs is common; Chlamydia coinfection occurs in about one-third of cases. Gonorrhea also increases susceptibility to acquiring HIV.
Diagnosis
Clinical manifestations depend on infection site, bacterial strain, host factors, sex, and coinfections. Many infections are asymptomatic in both sexes. Incubation is typically 2–7 days. In men, urethritis usually begins with dysuria followed by purulent discharge, and acute epididymitis is the most frequent complication. In women, urethritis can cause dysuria, frequency, and urgency, and cervicitis may develop with purulent discharge, cramping, dyspareunia, and postcoital or intermenstrual bleeding; symptoms often intensify around menstruation. Untreated infection can ascend, causing pelvic inflammatory disease with infertility and chronic pelvic pain. Conjunctivitis usually results from autoinoculation and can rapidly threaten vision. In neonates, infection is commonly ophthalmia neonatorum acquired during delivery; ocular prophylaxis with agents such as silver nitrate drops or tetracycline ointment is used for prevention. Disseminated gonococcal infection may present with fever, rash, tenosynovitis, and septic arthritis and can resemble an influenza-like illness without obvious mucosal symptoms, so urethral/cervical, rectal, and pharyngeal sites should be sampled.
Diagnostic Tests and Interpretation
Laboratory Studies
In symptomatic men, Gram stain of urethral discharge can show polymorphonuclear cells and gram-negative intracellular diplococci, but Gram stain performs poorly with endocervical, rectal, and pharyngeal specimens. Culture allows antimicrobial susceptibility testing and should be performed on selective media such as modified Thayer–Martin (or equivalent) with aerobic conditions and increased CO₂; rapid processing is essential because gonococci do not tolerate drying. Strains linked to dissemination may be more fastidious and harder to grow. Nucleic acid–based tests can detect N. gonorrhoeae from swabs or urine with sensitivity and specificity comparable or better than culture, but cost is higher and cross-reactivity with nonpathogenic Neisseria species can occur.
Differential Diagnosis
Urethritis can be nongonococcal due to Chlamydia, Ureaplasma, Mycoplasma genitalium, Haemophilus vaginalis, HSV, adenovirus, and others. Vaginal symptoms may reflect candidiasis, bacterial vaginosis, trichomoniasis, or noninfectious etiologies such as chemical irritation, allergy, fistula, or pregnancy-related leukorrhea. Disseminated gonococcal infection must be distinguished from meningococcemia, ecthyma gangrenosum, other bacteremias, septic arthritis from other bacteria, and reactive arthritis.
Treatment
Medications
CDC-recommended therapy has centered on cephalosporins. For uncomplicated urethral, cervical, or rectal infection, recommended single-dose options include ceftriaxone 125 mg IM, cefixime 400 mg PO, or spectinomycin 2 g IM. Pharyngeal infection is harder to eradicate and is treated with ceftriaxone 125 mg IM as the preferred regimen. Gonococcal conjunctivitis is treated with ceftriaxone 125 mg IM once, with saline eye irrigation as an optional adjunct. Disseminated infection is treated with parenteral cephalosporin-based regimens such as ceftriaxone 1 g IM/IV daily or cefotaxime/ceftizoxime 1 g IV three times daily, or spectinomycin 2 g IM twice daily; continue parenteral therapy for 24–48 hours after clinical improvement, then transition to an oral agent such as cefixime 400 mg PO twice daily to complete a total of one week. If chlamydial infection has not been excluded, provide concurrent chlamydia therapy. Fluoroquinolones are not recommended as first-line therapy in the United States because of widespread resistance.
Additional Treatment
Because Chlamydia coinfection is common, initial management should cover chlamydia (e.g., azithromycin or doxycycline) unless it has been ruled out.
Ongoing Care and Follow-Up
Patient Monitoring
A routine test-of-cure is not required after treating uncomplicated infection. If symptoms persist, obtain culture with susceptibility testing; the most common reason for apparent treatment failure is reinfection from an untreated partner.
Patient Education
Advise consistent condom use and provide instruction on correct condom use.
Complications
The most important complication is pelvic inflammatory disease from ascending infection, which can lead to tubo-ovarian abscess, pelvic peritonitis, and Fitz-Hugh–Curtis syndrome, with long-term infertility and chronic pelvic pain. In men, complications include epididymitis, periurethritis, balanitis, acute or chronic prostatitis, orchitis, seminal vasculitis, and infection of Tyson and Cowper glands. Disseminated gonococcemia is more common in women, with menstruation increasing risk, and typically causes tenosynovitis, migratory arthritis, and peripheral skin lesions that may be maculopapular or pustular; blood cultures are positive in only a minority of cases. Endocarditis and meningitis are rare in the antibiotic era.
- Published on
Infectious Diseases and Microbiology: Hepatosplenomegaly and Fever
Basics
Description
A midclavicular liver span of at least 12.5 cm supports hepatomegaly. Splenomegaly is defined as a spleen exceeding 250 g or one that is palpable, and on ultrasound is suggested by a cephalocaudal length of 13 cm or more
.
Approach to the Patient
Evaluating Hepatomegaly
Palpate to identify the lower liver edge at the right midclavicular line, then use gentle percussion to define the upper border so liver span can be measured; a span ≥12.5 cm supports hepatomegaly. Because hyperinflated lungs can push the liver downward, the upper border must be assessed to avoid overcalling enlargement.
Evaluating Splenomegaly
Bedside assessment should include both palpation and percussion. Palpation is best done bimanually with the patient supine and in the right lateral position. Percussion methods by Nixon and Castell provide the best diagnostic performance. In Nixon’s method, the patient lies on the right side and percussion begins in the posterior axillary line at the level where lung resonance ends, moving obliquely toward the left anterior costal margin; a dullness span over 8 cm suggests splenomegaly and has moderate sensitivity with high specificity. In Castell’s method, the patient is supine and percussion in the lowest intercostal space at the left anterior axillary line should remain resonant during inspiration if the spleen is normal; this approach has moderate sensitivity and specificity. If missing splenomegaly would change management, confirm with ultrasound or scintigraphy.
Evaluating Fever with Liver and/or Spleen Enlargement
Obtain a comprehensive history emphasizing travel and immigration, occupation, sexual history, intravenous drug use, animal exposure, and family history of malignancy, connective tissue disease, or inherited conditions. Look for associated findings including jaundice, fever duration and pattern, lymphadenopathy, rashes or bite exposures, liver edge texture and tenderness, an enlarged gallbladder or other abdominal mass, and spleen size and consistency. Initial testing commonly includes broad laboratory evaluation, heterophile antibody testing, hepatitis studies, imaging, and in selected cases bone marrow evaluation, endoscopy, and/or liver biopsy.
Epidemiology
In young adults, palpability of the liver and spleen can occur even without disease. In a large sample of healthy military personnel, the liver was not palpable or only at the costal margin in over half, and descended only 1–2 cm below the margin in many others. Studies of healthy college entrants have found a small proportion with unexplained palpable spleens, and palpable spleens have been reported in a notable minority of otherwise normal postpartum women.
Etiology
Hepatomegaly with Fever
Infectious causes include pyogenic or amoebic abscess, ascending cholangitis, chronic granulomatous disease, chronic Q fever, ehrlichiosis, histoplasmosis, HIV, infectious hepatitis, infectious mononucleosis, leptospirosis, syphilis, tuberculosis, and parasitic infections. Malignant causes include diffuse primary hepatic cancer, diffuse metastases, myeloproliferative disorders, lymphoma, and angiosarcoma. Inflammatory causes include sarcoidosis, autoimmune hepatitis, familial Mediterranean fever, and Still’s disease.
Splenomegaly with Fever
Infectious causes include viral infections such as hepatitis, infectious mononucleosis, and HIV; bacterial infections such as endocarditis, pyogenic abscess, salmonellosis, leptospirosis, brucellosis, Bartonella; fungal infections such as histoplasmosis; mycobacterial infections including miliary tuberculosis and nontuberculous mycobacteria; and parasitic infections including malaria, toxoplasmosis, amoebic liver abscess, schistosomiasis with Katayama fever, visceral leishmaniasis, babesiosis, and ehrlichiosis. Inflammatory causes include rheumatoid arthritis, sarcoidosis, systemic lupus erythematosus, and hemophagocytic lymphohistiocytosis. Malignant causes include lymphoma, acute and chronic leukemias, and myelodysplastic or myeloproliferative syndromes. Numerous parasites can enlarge liver and spleen depending on exposure context, including malaria, schistosomiasis, hydatid disease, leishmaniasis, toxocariasis, toxoplasmosis, liver flukes such as Fasciola hepatica, and echinococcal cysts, which can enlarge organs but are rarely febrile. Fever occurs in roughly half of toxoplasmosis and toxocariasis cases.
Diagnosis
History and Clinical Manifestations
In young adults, the combination of fatigue, sore throat, fever, lymphadenopathy, and hepatosplenomegaly is most often infectious mononucleosis. Fever with abdominal pain that may localize to the right upper quadrant, vomiting or anorexia, hepatomegaly, leukocytosis with elevated sedimentation rate, and otherwise unexplained anemia should raise concern for liver abscess. Pyogenic liver abscess most often arises from biliary disease and is commonly due to enteric organisms including Escherichia coli, Klebsiella, enterococci, anginosus group streptococci, and anaerobes, and is most often seen in adults in their fifth and sixth decades. Pyogenic liver abscess with metastatic infection such as endophthalmitis, meningitis, or other focal abscesses suggests Klebsiella pneumoniae, particularly in patients with diabetes and those from East Asia. Amoebic liver abscess is now most often seen in travelers and migrants; men have markedly higher risk of invasive Entamoeba histolytica disease including liver abscess, gastrointestinal symptoms such as nausea, vomiting, or diarrhea occur in a minority, and presentation may occur years after exposure. In HIV with advanced immunosuppression, fever with lymphadenopathy and splenomegaly is often mycobacterial, but lymphoma must be ruled out. Leptospirosis should be considered with compatible exposures and fever with rigors, headache, and myalgias, with severe disease involving pulmonary, hepatic, and renal dysfunction, aseptic meningitis, and bleeding tendencies. In tropical settings, splenomegaly may reflect hyper-reactive malarial splenomegaly, characterized by fever, anemia, weight loss, abdominal discomfort, lassitude, abnormal liver tests, elevated IgM, and hepatic sinusoidal lymphocytosis.
Physical Examination
Beyond confirming fever and organ enlargement, search for diagnostic clues such as lymphadenopathy suggesting lymphoma, infectious mononucleosis, brucellosis, schistosomiasis, HIV, or mycobacterial infection; rashes suggesting schistosomiasis, rickettsial disease, leishmaniasis, mononucleosis, Still’s disease, or syphilis; pharyngeal findings supporting mononucleosis; murmurs or embolic phenomena supporting endocarditis, Bartonella, or brucellosis; jaundice supporting viral hepatitis, cholangitis, or leptospirosis; conjunctival suffusion supporting leptospirosis; and joint findings supporting rheumatoid arthritis, lupus, or Still’s disease.
Diagnostic Tests and Interpretation
Laboratory Studies
Leukocytosis with a left shift supports bacterial infection. Marked lymphocytosis with atypical lymphocytes on smear supports infectious mononucleosis and can be confirmed early with heterophile antibody testing or with EBV viral capsid antigen IgM. Eosinophilia can accompany certain parasitic causes of hepatosplenomegaly but is not typical of amoebic infection. Three sets of blood cultures off antibiotics help exclude most endocarditis, while Bartonella, Brucella, and Q fever are better assessed by serology. Based on exposure history, obtain HIV, syphilis, and viral hepatitis testing, and consider serologies for rickettsial disease, Entamoeba, toxoplasma, schistosomiasis, Q fever, Fasciola, leptospirosis, and ehrlichiosis, along with blood films for malaria and babesiosis. Include biochemistry, autoimmune markers, and ferritin when inflammatory disease is considered. If imaging identifies an abscess, image-guided aspiration can establish diagnosis. Excisional lymph node biopsy or liver biopsy offers the highest yield for lymphoma. Bone marrow biopsy or splenic aspirate can diagnose leishmaniasis, with PCR or serology as alternatives.
Imaging
Ultrasound can confirm enlargement and identify causes such as abscess, hepatocellular carcinoma, or biliary pathology. Contrast-enhanced CT is helpful when ultrasound is nondiagnostic and suspicion remains for focal lesions or lymphoma. MRI is rarely needed but may help distinguish abscess from malignancy.
Treatment
Medications
Therapy is directed by the underlying diagnosis. Confirmed liver abscess requires antibiotics targeting likely organisms; pyogenic abscess is generally managed with percutaneous drainage plus antibiotics, with surgery reserved for failed drainage or complex multiloculated disease. Praziquantel is effective for Schistosoma mansoni in advanced hepatosplenic disease and is preferred when Schistosoma haematobium coinfection is present. Fascioliasis is typically treated with triclabendazole 10 mg/kg for one to two days; bithionol is an alternative, and the role of praziquantel is uncertain.
Ongoing Care and Follow-Up
Advise patients with splenomegaly to avoid contact sports and monitor for spontaneous rupture, which almost always presents with severe upper abdominal pain that often starts in the left upper quadrant, spreads more diffusely, and can radiate to the left shoulder.
Complications
In the United States, spontaneous splenic rupture is most commonly associated with infectious mononucleosis. Although rare, occurring in a small fraction of mononucleosis cases, it is the leading cause of death related to infectious mononucleosis.
Basics
Description
A midclavicular liver span of at least 12.5 cm supports hepatomegaly. Splenomegaly is defined as a spleen exceeding 250 g or one that is palpable, and on ultrasound is suggested by a cephalocaudal length of 13 cm or more
.
Approach to the Patient
Evaluating Hepatomegaly
Palpate to identify the lower liver edge at the right midclavicular line, then use gentle percussion to define the upper border so liver span can be measured; a span ≥12.5 cm supports hepatomegaly. Because hyperinflated lungs can push the liver downward, the upper border must be assessed to avoid overcalling enlargement.
Evaluating Splenomegaly
Bedside assessment should include both palpation and percussion. Palpation is best done bimanually with the patient supine and in the right lateral position. Percussion methods by Nixon and Castell provide the best diagnostic performance. In Nixon’s method, the patient lies on the right side and percussion begins in the posterior axillary line at the level where lung resonance ends, moving obliquely toward the left anterior costal margin; a dullness span over 8 cm suggests splenomegaly and has moderate sensitivity with high specificity. In Castell’s method, the patient is supine and percussion in the lowest intercostal space at the left anterior axillary line should remain resonant during inspiration if the spleen is normal; this approach has moderate sensitivity and specificity. If missing splenomegaly would change management, confirm with ultrasound or scintigraphy.
Evaluating Fever with Liver and/or Spleen Enlargement
Obtain a comprehensive history emphasizing travel and immigration, occupation, sexual history, intravenous drug use, animal exposure, and family history of malignancy, connective tissue disease, or inherited conditions. Look for associated findings including jaundice, fever duration and pattern, lymphadenopathy, rashes or bite exposures, liver edge texture and tenderness, an enlarged gallbladder or other abdominal mass, and spleen size and consistency. Initial testing commonly includes broad laboratory evaluation, heterophile antibody testing, hepatitis studies, imaging, and in selected cases bone marrow evaluation, endoscopy, and/or liver biopsy.
Epidemiology
In young adults, palpability of the liver and spleen can occur even without disease. In a large sample of healthy military personnel, the liver was not palpable or only at the costal margin in over half, and descended only 1–2 cm below the margin in many others. Studies of healthy college entrants have found a small proportion with unexplained palpable spleens, and palpable spleens have been reported in a notable minority of otherwise normal postpartum women.
Etiology
Hepatomegaly with Fever
Infectious causes include pyogenic or amoebic abscess, ascending cholangitis, chronic granulomatous disease, chronic Q fever, ehrlichiosis, histoplasmosis, HIV, infectious hepatitis, infectious mononucleosis, leptospirosis, syphilis, tuberculosis, and parasitic infections. Malignant causes include diffuse primary hepatic cancer, diffuse metastases, myeloproliferative disorders, lymphoma, and angiosarcoma. Inflammatory causes include sarcoidosis, autoimmune hepatitis, familial Mediterranean fever, and Still’s disease.
Splenomegaly with Fever
Infectious causes include viral infections such as hepatitis, infectious mononucleosis, and HIV; bacterial infections such as endocarditis, pyogenic abscess, salmonellosis, leptospirosis, brucellosis, Bartonella; fungal infections such as histoplasmosis; mycobacterial infections including miliary tuberculosis and nontuberculous mycobacteria; and parasitic infections including malaria, toxoplasmosis, amoebic liver abscess, schistosomiasis with Katayama fever, visceral leishmaniasis, babesiosis, and ehrlichiosis. Inflammatory causes include rheumatoid arthritis, sarcoidosis, systemic lupus erythematosus, and hemophagocytic lymphohistiocytosis. Malignant causes include lymphoma, acute and chronic leukemias, and myelodysplastic or myeloproliferative syndromes. Numerous parasites can enlarge liver and spleen depending on exposure context, including malaria, schistosomiasis, hydatid disease, leishmaniasis, toxocariasis, toxoplasmosis, liver flukes such as Fasciola hepatica, and echinococcal cysts, which can enlarge organs but are rarely febrile. Fever occurs in roughly half of toxoplasmosis and toxocariasis cases.
Diagnosis
History and Clinical Manifestations
In young adults, the combination of fatigue, sore throat, fever, lymphadenopathy, and hepatosplenomegaly is most often infectious mononucleosis. Fever with abdominal pain that may localize to the right upper quadrant, vomiting or anorexia, hepatomegaly, leukocytosis with elevated sedimentation rate, and otherwise unexplained anemia should raise concern for liver abscess. Pyogenic liver abscess most often arises from biliary disease and is commonly due to enteric organisms including Escherichia coli, Klebsiella, enterococci, anginosus group streptococci, and anaerobes, and is most often seen in adults in their fifth and sixth decades. Pyogenic liver abscess with metastatic infection such as endophthalmitis, meningitis, or other focal abscesses suggests Klebsiella pneumoniae, particularly in patients with diabetes and those from East Asia. Amoebic liver abscess is now most often seen in travelers and migrants; men have markedly higher risk of invasive Entamoeba histolytica disease including liver abscess, gastrointestinal symptoms such as nausea, vomiting, or diarrhea occur in a minority, and presentation may occur years after exposure. In HIV with advanced immunosuppression, fever with lymphadenopathy and splenomegaly is often mycobacterial, but lymphoma must be ruled out. Leptospirosis should be considered with compatible exposures and fever with rigors, headache, and myalgias, with severe disease involving pulmonary, hepatic, and renal dysfunction, aseptic meningitis, and bleeding tendencies. In tropical settings, splenomegaly may reflect hyper-reactive malarial splenomegaly, characterized by fever, anemia, weight loss, abdominal discomfort, lassitude, abnormal liver tests, elevated IgM, and hepatic sinusoidal lymphocytosis.
Physical Examination
Beyond confirming fever and organ enlargement, search for diagnostic clues such as lymphadenopathy suggesting lymphoma, infectious mononucleosis, brucellosis, schistosomiasis, HIV, or mycobacterial infection; rashes suggesting schistosomiasis, rickettsial disease, leishmaniasis, mononucleosis, Still’s disease, or syphilis; pharyngeal findings supporting mononucleosis; murmurs or embolic phenomena supporting endocarditis, Bartonella, or brucellosis; jaundice supporting viral hepatitis, cholangitis, or leptospirosis; conjunctival suffusion supporting leptospirosis; and joint findings supporting rheumatoid arthritis, lupus, or Still’s disease.
Diagnostic Tests and Interpretation
Laboratory Studies
Leukocytosis with a left shift supports bacterial infection. Marked lymphocytosis with atypical lymphocytes on smear supports infectious mononucleosis and can be confirmed early with heterophile antibody testing or with EBV viral capsid antigen IgM. Eosinophilia can accompany certain parasitic causes of hepatosplenomegaly but is not typical of amoebic infection. Three sets of blood cultures off antibiotics help exclude most endocarditis, while Bartonella, Brucella, and Q fever are better assessed by serology. Based on exposure history, obtain HIV, syphilis, and viral hepatitis testing, and consider serologies for rickettsial disease, Entamoeba, toxoplasma, schistosomiasis, Q fever, Fasciola, leptospirosis, and ehrlichiosis, along with blood films for malaria and babesiosis. Include biochemistry, autoimmune markers, and ferritin when inflammatory disease is considered. If imaging identifies an abscess, image-guided aspiration can establish diagnosis. Excisional lymph node biopsy or liver biopsy offers the highest yield for lymphoma. Bone marrow biopsy or splenic aspirate can diagnose leishmaniasis, with PCR or serology as alternatives.
Imaging
Ultrasound can confirm enlargement and identify causes such as abscess, hepatocellular carcinoma, or biliary pathology. Contrast-enhanced CT is helpful when ultrasound is nondiagnostic and suspicion remains for focal lesions or lymphoma. MRI is rarely needed but may help distinguish abscess from malignancy.
Treatment
Medications
Therapy is directed by the underlying diagnosis. Confirmed liver abscess requires antibiotics targeting likely organisms; pyogenic abscess is generally managed with percutaneous drainage plus antibiotics, with surgery reserved for failed drainage or complex multiloculated disease. Praziquantel is effective for Schistosoma mansoni in advanced hepatosplenic disease and is preferred when Schistosoma haematobium coinfection is present. Fascioliasis is typically treated with triclabendazole 10 mg/kg for one to two days; bithionol is an alternative, and the role of praziquantel is uncertain.
Ongoing Care and Follow-Up
Advise patients with splenomegaly to avoid contact sports and monitor for spontaneous rupture, which almost always presents with severe upper abdominal pain that often starts in the left upper quadrant, spreads more diffusely, and can radiate to the left shoulder.
Complications
In the United States, spontaneous splenic rupture is most commonly associated with infectious mononucleosis. Although rare, occurring in a small fraction of mononucleosis cases, it is the leading cause of death related to infectious mononucleosis.
- Published on
Infectious Diseases and Microbiology: Insect Bites and Stings
Basics
Description
Zoonoses are infections transmitted from nonhuman animals to humans, and vectors are the animals responsible for transmission. Insect bites and stings can lead to a wide spectrum of infectious diseases with acute, subacute, or highly variable presentations. Noninfectious reactions such as anaphylaxis and inflammatory responses are also common.
Approach to the Patient
Clinical evaluation requires awareness of geographic distribution, vector life cycles, and characteristic clinical syndromes. A detailed history of mosquito or tick exposure and the timing of bites can help narrow the differential diagnosis. Travel history is critical and should include dates, destinations, stopovers, pretravel medical advice, vaccinations, malaria prophylaxis, and preventive measures such as bed nets or repellents. Laboratory confirmation may support the diagnosis but is often unavailable early in illness. Multiple infections can follow a single exposure, as some vectors transmit more than one pathogen simultaneously. Malaria must always be considered in febrile travelers returning from endemic regions and treated as a medical emergency; given the risk of severe outcomes, empiric antimicrobial therapy is often appropriate when suspicion is high.
Epidemiology
Hundreds of thousands of Lyme disease cases have been reported in the United States, with most occurring in the Northeast, Minnesota, and Wisconsin. Rocky Mountain spotted fever occurs throughout the Americas, predominantly in the southern and southeastern United States, with higher incidence in warmer months. West Nile virus has been present in the US since 1999, with tens of thousands of reported cases; most infections are asymptomatic, and true exposure rates are likely much higher. Eastern equine encephalitis is a rare but severe mosquito-borne viral infection found mainly along the East and Gulf coasts, reported sporadically over decades. Malaria remains an important imported infection, with over a thousand cases reported annually in the US.
General Prevention
In areas with tick exposure, preventive strategies include wearing protective clothing and using proper tick-removal techniques with fine tweezers, avoiding crushing or abrupt removal. Insect repellents containing DEET remain the most effective option, particularly when combined with permethrin-treated clothing. Concentrations of 10–30% DEET provide strong protection; higher concentrations do not significantly increase efficacy. Plant-based repellents such as picaridin, PMD, or citronella have some benefit but are less effective than DEET.
Etiology
In the United States, clinicians may encounter both local and imported vector-borne diseases. Mosquitoes transmit malaria, dengue, West Nile virus, yellow fever, chikungunya, and viral encephalitides including eastern equine encephalitis. Ticks transmit Lyme disease, babesiosis, ehrlichiosis, anaplasmosis, Rocky Mountain spotted fever, tularemia, southern tick–associated rash illness, Bartonella infection, tick paralysis, and other rickettsioses. Flies may transmit bartonellosis, African trypanosomiasis, filariasis, onchocerciasis, leishmaniasis, or cause myiasis. Fleas transmit plague, murine typhus, and tungiasis.
Diagnosis
Incubation periods and symptom patterns vary by pathogen. Falciparum malaria typically incubates for about two weeks and presents with fever, chills, headache, abdominal or neck pain, nausea, vomiting, and sometimes jaundice. West Nile virus incubates for up to two weeks; most cases are asymptomatic, while symptomatic illness usually causes short-lived fever, myalgias, headache, and sometimes rash, with possible neurologic involvement. Colorado tick fever presents after several days with biphasic fever, severe headache, photophobia, and myalgias, occasionally with a transient rash. Dengue usually incubates for several days to two weeks and classically causes fever, retro-orbital headache, rash, and marked muscle and joint pain.
Diagnostic Tests and Interpretation
Laboratory evaluation depends on the suspected condition. Blood smears are mandatory in febrile patients returning from malaria-endemic regions. Lyme disease is diagnosed by serology with enzyme immunoassay confirmed by Western blot in compatible cases. Babesiosis is identified on blood smear by intraerythrocytic parasites, with PCR and serology as adjuncts. West Nile virus infection is diagnosed by IgM detection in serum or cerebrospinal fluid. Neuroimaging in eastern equine encephalitis often reveals characteristic thalamic and basal ganglia abnormalities.
Treatment
Management depends on the specific infection and is detailed in disease-specific references. Given the severity of some vector-borne illnesses, prompt empiric therapy is often warranted when clinical suspicion is high.
Ongoing Care and Complications
Eastern equine encephalitis carries a high mortality rate, and many survivors have permanent neurologic disability. Delayed diagnosis and treatment of falciparum malaria significantly increase mortality and the risk of permanent neurologic damage. Lyme disease may involve the nervous system or cardiac conduction pathways, leading to neurologic deficits or arrhythmias. Dengue may cause mucosal bleeding and exacerbate preexisting gastrointestinal lesions. Colorado tick fever has been associated with rare but serious complications including encephalitis, meningitis, hemorrhage, myocarditis, orchitis, atypical pneumonia, and hepatitis.
Basics
Description
Zoonoses are infections transmitted from nonhuman animals to humans, and vectors are the animals responsible for transmission. Insect bites and stings can lead to a wide spectrum of infectious diseases with acute, subacute, or highly variable presentations. Noninfectious reactions such as anaphylaxis and inflammatory responses are also common.
Approach to the Patient
Clinical evaluation requires awareness of geographic distribution, vector life cycles, and characteristic clinical syndromes. A detailed history of mosquito or tick exposure and the timing of bites can help narrow the differential diagnosis. Travel history is critical and should include dates, destinations, stopovers, pretravel medical advice, vaccinations, malaria prophylaxis, and preventive measures such as bed nets or repellents. Laboratory confirmation may support the diagnosis but is often unavailable early in illness. Multiple infections can follow a single exposure, as some vectors transmit more than one pathogen simultaneously. Malaria must always be considered in febrile travelers returning from endemic regions and treated as a medical emergency; given the risk of severe outcomes, empiric antimicrobial therapy is often appropriate when suspicion is high.
Epidemiology
Hundreds of thousands of Lyme disease cases have been reported in the United States, with most occurring in the Northeast, Minnesota, and Wisconsin. Rocky Mountain spotted fever occurs throughout the Americas, predominantly in the southern and southeastern United States, with higher incidence in warmer months. West Nile virus has been present in the US since 1999, with tens of thousands of reported cases; most infections are asymptomatic, and true exposure rates are likely much higher. Eastern equine encephalitis is a rare but severe mosquito-borne viral infection found mainly along the East and Gulf coasts, reported sporadically over decades. Malaria remains an important imported infection, with over a thousand cases reported annually in the US.
General Prevention
In areas with tick exposure, preventive strategies include wearing protective clothing and using proper tick-removal techniques with fine tweezers, avoiding crushing or abrupt removal. Insect repellents containing DEET remain the most effective option, particularly when combined with permethrin-treated clothing. Concentrations of 10–30% DEET provide strong protection; higher concentrations do not significantly increase efficacy. Plant-based repellents such as picaridin, PMD, or citronella have some benefit but are less effective than DEET.
Etiology
In the United States, clinicians may encounter both local and imported vector-borne diseases. Mosquitoes transmit malaria, dengue, West Nile virus, yellow fever, chikungunya, and viral encephalitides including eastern equine encephalitis. Ticks transmit Lyme disease, babesiosis, ehrlichiosis, anaplasmosis, Rocky Mountain spotted fever, tularemia, southern tick–associated rash illness, Bartonella infection, tick paralysis, and other rickettsioses. Flies may transmit bartonellosis, African trypanosomiasis, filariasis, onchocerciasis, leishmaniasis, or cause myiasis. Fleas transmit plague, murine typhus, and tungiasis.
Diagnosis
Incubation periods and symptom patterns vary by pathogen. Falciparum malaria typically incubates for about two weeks and presents with fever, chills, headache, abdominal or neck pain, nausea, vomiting, and sometimes jaundice. West Nile virus incubates for up to two weeks; most cases are asymptomatic, while symptomatic illness usually causes short-lived fever, myalgias, headache, and sometimes rash, with possible neurologic involvement. Colorado tick fever presents after several days with biphasic fever, severe headache, photophobia, and myalgias, occasionally with a transient rash. Dengue usually incubates for several days to two weeks and classically causes fever, retro-orbital headache, rash, and marked muscle and joint pain.
Diagnostic Tests and Interpretation
Laboratory evaluation depends on the suspected condition. Blood smears are mandatory in febrile patients returning from malaria-endemic regions. Lyme disease is diagnosed by serology with enzyme immunoassay confirmed by Western blot in compatible cases. Babesiosis is identified on blood smear by intraerythrocytic parasites, with PCR and serology as adjuncts. West Nile virus infection is diagnosed by IgM detection in serum or cerebrospinal fluid. Neuroimaging in eastern equine encephalitis often reveals characteristic thalamic and basal ganglia abnormalities.
Treatment
Management depends on the specific infection and is detailed in disease-specific references. Given the severity of some vector-borne illnesses, prompt empiric therapy is often warranted when clinical suspicion is high.
Ongoing Care and Complications
Eastern equine encephalitis carries a high mortality rate, and many survivors have permanent neurologic disability. Delayed diagnosis and treatment of falciparum malaria significantly increase mortality and the risk of permanent neurologic damage. Lyme disease may involve the nervous system or cardiac conduction pathways, leading to neurologic deficits or arrhythmias. Dengue may cause mucosal bleeding and exacerbate preexisting gastrointestinal lesions. Colorado tick fever has been associated with rare but serious complications including encephalitis, meningitis, hemorrhage, myocarditis, orchitis, atypical pneumonia, and hepatitis.
- Published on
Infectious Diseases and Microbiology: Insect Bites and Stings
Basics
Description
Zoonoses are infections transmitted from nonhuman animals to humans, and vectors are the animals responsible for transmission. Insect bites and stings can lead to a wide spectrum of infectious diseases with acute, subacute, or highly variable presentations. Noninfectious reactions such as anaphylaxis and inflammatory responses are also common.
Approach to the Patient
Clinical evaluation requires awareness of geographic distribution, vector life cycles, and characteristic clinical syndromes. A detailed history of mosquito or tick exposure and the timing of bites can help narrow the differential diagnosis. Travel history is critical and should include dates, destinations, stopovers, pretravel medical advice, vaccinations, malaria prophylaxis, and preventive measures such as bed nets or repellents. Laboratory confirmation may support the diagnosis but is often unavailable early in illness. Multiple infections can follow a single exposure, as some vectors transmit more than one pathogen simultaneously. Malaria must always be considered in febrile travelers returning from endemic regions and treated as a medical emergency; given the risk of severe outcomes, empiric antimicrobial therapy is often appropriate when suspicion is high.
Epidemiology
Hundreds of thousands of Lyme disease cases have been reported in the United States, with most occurring in the Northeast, Minnesota, and Wisconsin. Rocky Mountain spotted fever occurs throughout the Americas, predominantly in the southern and southeastern United States, with higher incidence in warmer months. West Nile virus has been present in the US since 1999, with tens of thousands of reported cases; most infections are asymptomatic, and true exposure rates are likely much higher. Eastern equine encephalitis is a rare but severe mosquito-borne viral infection found mainly along the East and Gulf coasts, reported sporadically over decades. Malaria remains an important imported infection, with over a thousand cases reported annually in the US.
General Prevention
In areas with tick exposure, preventive strategies include wearing protective clothing and using proper tick-removal techniques with fine tweezers, avoiding crushing or abrupt removal. Insect repellents containing DEET remain the most effective option, particularly when combined with permethrin-treated clothing. Concentrations of 10–30% DEET provide strong protection; higher concentrations do not significantly increase efficacy. Plant-based repellents such as picaridin, PMD, or citronella have some benefit but are less effective than DEET.
Etiology
In the United States, clinicians may encounter both local and imported vector-borne diseases. Mosquitoes transmit malaria, dengue, West Nile virus, yellow fever, chikungunya, and viral encephalitides including eastern equine encephalitis. Ticks transmit Lyme disease, babesiosis, ehrlichiosis, anaplasmosis, Rocky Mountain spotted fever, tularemia, southern tick–associated rash illness, Bartonella infection, tick paralysis, and other rickettsioses. Flies may transmit bartonellosis, African trypanosomiasis, filariasis, onchocerciasis, leishmaniasis, or cause myiasis. Fleas transmit plague, murine typhus, and tungiasis.
Diagnosis
Incubation periods and symptom patterns vary by pathogen. Falciparum malaria typically incubates for about two weeks and presents with fever, chills, headache, abdominal or neck pain, nausea, vomiting, and sometimes jaundice. West Nile virus incubates for up to two weeks; most cases are asymptomatic, while symptomatic illness usually causes short-lived fever, myalgias, headache, and sometimes rash, with possible neurologic involvement. Colorado tick fever presents after several days with biphasic fever, severe headache, photophobia, and myalgias, occasionally with a transient rash. Dengue usually incubates for several days to two weeks and classically causes fever, retro-orbital headache, rash, and marked muscle and joint pain. bisnes
Nenek dia
Diagnostic Tests and Interpretation
Laboratory evaluation depends on the suspected condition. Blood smears are mandatory in febrile patients returning from malaria-endemic regions. Lyme disease is diagnosed by serology with enzyme immunoassay confirmed by Western blot in compatible cases. Babesiosis is identified on blood smear by intraerythrocytic parasites, with PCR and serology as adjuncts. West Nile virus infection is diagnosed by IgM detection in serum or cerebrospinal fluid. Neuroimaging in eastern equine encephalitis often reveals characteristic thalamic and basal ganglia abnormalities.
Treatment
Management depends on the specific infection and is detailed in disease-specific references. Given the severity of some vector-borne illnesses, prompt empiric therapy is often warranted when clinical suspicion is high.
Ongoing Care and Complications
Eastern equine encephalitis carries a high mortality rate, and many survivors have permanent neurologic disability. Delayed diagnosis and treatment of falciparum malaria significantly increase mortality and the risk of permanent neurologic damage. Lyme disease may involve the nervous system or cardiac conduction pathways, leading to neurologic deficits or arrhythmias. Dengue may cause mucosal bleeding and exacerbate preexisting gastrointestinal lesions. Colorado tick fever has been associated with rare but serious complications including encephalitis, meningitis, hemorrhage, myocarditis, orchitis, atypical pneumonia, and hepatitis.
Basics
Description
Zoonoses are infections transmitted from nonhuman animals to humans, and vectors are the animals responsible for transmission. Insect bites and stings can lead to a wide spectrum of infectious diseases with acute, subacute, or highly variable presentations. Noninfectious reactions such as anaphylaxis and inflammatory responses are also common.
Approach to the Patient
Clinical evaluation requires awareness of geographic distribution, vector life cycles, and characteristic clinical syndromes. A detailed history of mosquito or tick exposure and the timing of bites can help narrow the differential diagnosis. Travel history is critical and should include dates, destinations, stopovers, pretravel medical advice, vaccinations, malaria prophylaxis, and preventive measures such as bed nets or repellents. Laboratory confirmation may support the diagnosis but is often unavailable early in illness. Multiple infections can follow a single exposure, as some vectors transmit more than one pathogen simultaneously. Malaria must always be considered in febrile travelers returning from endemic regions and treated as a medical emergency; given the risk of severe outcomes, empiric antimicrobial therapy is often appropriate when suspicion is high.
Epidemiology
Hundreds of thousands of Lyme disease cases have been reported in the United States, with most occurring in the Northeast, Minnesota, and Wisconsin. Rocky Mountain spotted fever occurs throughout the Americas, predominantly in the southern and southeastern United States, with higher incidence in warmer months. West Nile virus has been present in the US since 1999, with tens of thousands of reported cases; most infections are asymptomatic, and true exposure rates are likely much higher. Eastern equine encephalitis is a rare but severe mosquito-borne viral infection found mainly along the East and Gulf coasts, reported sporadically over decades. Malaria remains an important imported infection, with over a thousand cases reported annually in the US.
General Prevention
In areas with tick exposure, preventive strategies include wearing protective clothing and using proper tick-removal techniques with fine tweezers, avoiding crushing or abrupt removal. Insect repellents containing DEET remain the most effective option, particularly when combined with permethrin-treated clothing. Concentrations of 10–30% DEET provide strong protection; higher concentrations do not significantly increase efficacy. Plant-based repellents such as picaridin, PMD, or citronella have some benefit but are less effective than DEET.
Etiology
In the United States, clinicians may encounter both local and imported vector-borne diseases. Mosquitoes transmit malaria, dengue, West Nile virus, yellow fever, chikungunya, and viral encephalitides including eastern equine encephalitis. Ticks transmit Lyme disease, babesiosis, ehrlichiosis, anaplasmosis, Rocky Mountain spotted fever, tularemia, southern tick–associated rash illness, Bartonella infection, tick paralysis, and other rickettsioses. Flies may transmit bartonellosis, African trypanosomiasis, filariasis, onchocerciasis, leishmaniasis, or cause myiasis. Fleas transmit plague, murine typhus, and tungiasis.
Diagnosis
Incubation periods and symptom patterns vary by pathogen. Falciparum malaria typically incubates for about two weeks and presents with fever, chills, headache, abdominal or neck pain, nausea, vomiting, and sometimes jaundice. West Nile virus incubates for up to two weeks; most cases are asymptomatic, while symptomatic illness usually causes short-lived fever, myalgias, headache, and sometimes rash, with possible neurologic involvement. Colorado tick fever presents after several days with biphasic fever, severe headache, photophobia, and myalgias, occasionally with a transient rash. Dengue usually incubates for several days to two weeks and classically causes fever, retro-orbital headache, rash, and marked muscle and joint pain. bisnes
Nenek dia
Diagnostic Tests and Interpretation
Laboratory evaluation depends on the suspected condition. Blood smears are mandatory in febrile patients returning from malaria-endemic regions. Lyme disease is diagnosed by serology with enzyme immunoassay confirmed by Western blot in compatible cases. Babesiosis is identified on blood smear by intraerythrocytic parasites, with PCR and serology as adjuncts. West Nile virus infection is diagnosed by IgM detection in serum or cerebrospinal fluid. Neuroimaging in eastern equine encephalitis often reveals characteristic thalamic and basal ganglia abnormalities.
Treatment
Management depends on the specific infection and is detailed in disease-specific references. Given the severity of some vector-borne illnesses, prompt empiric therapy is often warranted when clinical suspicion is high.
Ongoing Care and Complications
Eastern equine encephalitis carries a high mortality rate, and many survivors have permanent neurologic disability. Delayed diagnosis and treatment of falciparum malaria significantly increase mortality and the risk of permanent neurologic damage. Lyme disease may involve the nervous system or cardiac conduction pathways, leading to neurologic deficits or arrhythmias. Dengue may cause mucosal bleeding and exacerbate preexisting gastrointestinal lesions. Colorado tick fever has been associated with rare but serious complications including encephalitis, meningitis, hemorrhage, myocarditis, orchitis, atypical pneumonia, and hepatitis.
- Published on
Emergency and Acute Medicine – Joint Pain and Fever
Overview and Definitions
Joint pain accompanied by fever suggests an inflammatory or infectious process and requires prompt evaluation. Joint involvement may be monoarticular, oligoarticular, or polyarticular and may be symmetric or asymmetric. Arthritis refers to inflammation of a joint and is a clinical finding rather than a diagnosis, whereas arthralgia denotes joint pain without objective inflammation. Acute joint disorders last less than six weeks, while chronic disorders persist beyond this duration.
Clinical Approach
The presence of fever narrows the differential diagnosis toward infectious, crystal-induced, immune-mediated, or reactive etiologies. Noninflammatory disorders such as osteoarthritis or fibromyalgia are rarely associated with fever. History should focus on onset and tempo of symptoms, recent infections, travel, trauma, sexual exposure, immunosuppression, and prior joint disease. Physical examination should assess for warmth, erythema, swelling, effusion, and limitation of motion, as well as extra-articular features such as rash, cardiac murmurs, or enthesitis. Synovial fluid aspiration and analysis are mandatory in acute monoarthritis or when infection or crystal disease is suspected.
Epidemiology
Septic arthritis is usually monoarticular, with polyarticular involvement occurring in 10–20% of adults. Risk factors include diabetes mellitus, chronic kidney disease, malignancy, immunosuppression, intravenous drug use, trauma, prosthetic joints, and underlying joint disease. Musculoskeletal manifestations occur in up to 45% of patients with infective endocarditis. Viral outbreaks, particularly chikungunya, have caused large numbers of cases of acute febrile polyarthritis, especially among travelers.
Etiology and Pathophysiology
Septic arthritis is the most important diagnosis to exclude and is most commonly caused by Staphylococcus aureus. Other infectious causes include disseminated gonococcal infection, endocarditis, Lyme disease, Whipple’s disease, secondary syphilis, and mycobacterial or fungal infections. Viral etiologies include parvovirus B19, acute HIV infection, hepatitis B, dengue virus, and chikungunya. Noninfectious causes include gout, pseudogout, acute rheumatic fever, adult-onset Still’s disease, systemic lupus erythematosus, vasculitis, and rarely malignancy.
Diagnostic Evaluation
Synovial fluid analysis is central to diagnosis. Bacterial arthritis is suggested by leukocyte counts greater than 50,000 cells/µL with polymorphonuclear predominance, turbid appearance, and low viscosity. Gram stain and culture should always be performed, and blood cultures obtained in acute presentations. Gonococcal arthritis frequently yields negative synovial cultures, requiring sampling of mucosal sites. Elevated ESR and CRP favor bacterial infection, while markedly elevated ferritin levels suggest adult-onset Still’s disease.
Management
Suspected septic arthritis requires immediate empiric antimicrobial therapy after appropriate cultures are obtained. Most cases of nongonococcal septic arthritis require surgical drainage or joint washout. Gonococcal arthritis is usually managed medically with ceftriaxone. NSAIDs provide symptomatic relief in viral and reactive arthritis. Early joint immobilization followed by gradual mobilization is recommended once infection is controlled.
Complications
Delayed or inadequate treatment of septic arthritis may result in irreversible joint destruction, osteomyelitis, bacteremia, and systemic sepsis.
- Published on
Emergency and Acute Medicine – Lung Nodules
Overview and Definitions
Pulmonary nodules are rounded opacities surrounded by lung parenchyma and are typically less than 3–4 cm in diameter; larger lesions are classified as lung masses. Pathologically, a pulmonary nodule is a small, approximately spherical, circumscribed focus of abnormal tissue, while radiologically it is defined as a round opacity, at least moderately well marginated, and no more than 3 cm in maximum diameter. Linear or planar opacities are not considered nodules. Chest imaging may reveal a solitary pulmonary nodule, often referred to as a coin lesion, or multiple pulmonary nodules.
Clinical Approach
The primary objective is to distinguish benign from malignant nodules. Evaluation begins with a thorough history, as the probability of malignancy increases with age and is rare in patients younger than 35 years. Important malignancy risk factors include prior lung cancer, family history of lung cancer, cigarette smoking, second-hand smoke exposure, occupational carcinogen exposure such as asbestos or radon, pulmonary fibrosis, chronic obstructive pulmonary disease, and alpha-1 antitrypsin deficiency. A higher cumulative smoking burden is associated with increased cancer risk. If malignancy is suspected, it is essential to determine whether the lesion represents a primary lung cancer or metastatic disease. Fever suggests an infectious etiology, and immunocompromised patients are at risk for opportunistic infections presenting as solitary or multiple nodules. Physical examination may reveal signs of malignancy including cachexia, anemia, jaundice, clubbing, bone pain, abdominal masses, or superior vena cava syndrome. Radiologic features such as size, distribution, shape, calcification pattern, cavitation, lymphadenopathy, pleural effusion, and clustering provide diagnostic clues. Low-risk nodules may be followed with serial CT imaging, whereas larger or suspicious nodules warrant biopsy, PET imaging, or video-assisted thoracoscopic surgery. Empiric antimicrobial therapy should be initiated in immunocompromised patients or those at risk for rapid deterioration.
Epidemiology
Pulmonary nodules are common, with up to 51% of smokers aged 50 years or older having nodules detected on CT. Fewer than 1% of nodules smaller than 5 mm are malignant in patients without a history of cancer. The likelihood of malignancy increases with size: approximately 0.2% for nodules under 3 mm, 0.9% for 4–7 mm, 18% for 8–20 mm, and greater than 50% for nodules larger than 20 mm. Male smokers have a tenfold increased risk of lung cancer compared with nonsmokers, rising to 15–35 times higher in heavy smokers. Paragonimus westermani infection can present as a lung nodule in endemic regions of East and Southeast Asia. Tuberculosis commonly presents with hilar lymphadenopathy, and histoplasmosis is the most frequent cause of hospitalization from endemic mycoses in the United States.
Etiology and Pathophysiology
Solitary pulmonary nodules may be caused by primary lung malignancies including adenocarcinoma, squamous cell carcinoma, large cell carcinoma, and small cell carcinoma, as well as metastatic disease from breast, head and neck, thyroid, melanoma, colon, kidney, sarcoma, and germ cell tumors. Other causes include carcinoid tumors, infections such as bacterial abscesses, tuberculosis, atypical mycobacteria, histoplasmosis, blastomycosis, coccidioidomycosis, cryptococcosis, aspergilloma, nocardiosis, Pneumocystis infection, and parasitic infections including echinococcosis, dirofilariasis, ascariasis, and paragonimiasis. Benign neoplasms include hamartoma, lipoma, and fibroma. Non-neoplastic causes include arteriovenous malformations, bronchogenic cysts, granulomatosis with polyangiitis, sarcoidosis, rheumatoid nodules, amyloidoma, rounded atelectasis, intrapulmonary lymph nodes, hematoma, pulmonary infarction, and mucoid impaction. Multiple pulmonary nodules are more often benign when less than 1 cm, but in patients with known malignancy, nodules larger than 0.5 cm are more likely metastatic. Infectious causes of multiple nodules include septic emboli, fungal infections, tuberculosis, atypical mycobacteria, and paragonimiasis, while inflammatory conditions such as sarcoidosis, rheumatoid arthritis, and vasculitis are also common causes.
Diagnostic Evaluation
History should assess for tuberculosis risk factors, immunosuppression, aspiration risk, and exposure to endemic fungi. Lung abscesses may arise from aspiration, tricuspid valve endocarditis, or septic thrombophlebitis such as Lemierre syndrome, often in patients with poor dentition or prolonged recumbency. Symptoms include cough, sputum production, dyspnea, fever, night sweats, weight loss, and anorexia. Laboratory evaluation may include blood cultures, sputum Gram stain and culture, fungal cultures, acid-fast bacilli staining and mycobacterial cultures, cryptococcal antigen testing, galactomannan and beta-D-glucan assays, and serologic testing for endemic fungi. Imaging with high-resolution CT can detect nodules as small as 1–2 mm. Benign calcification patterns include homogeneous, central, concentric, and popcorn calcifications, while malignant features include eccentric or amorphous calcification and spiculated borders. Ground-glass halos suggest invasive fungal infection, particularly aspergillosis. PET imaging identifies metabolically active lesions. Transthoracic echocardiography is indicated when septic emboli are suspected, and CT of the neck should be performed if Lemierre syndrome is considered. Percutaneous biopsy or VATS is indicated when malignancy risk is high.
Management
Empiric antibiotics should be initiated in patients with fever or systemic toxicity after obtaining blood cultures. Suspected tuberculosis requires differentiation between latent and active disease using clinical assessment, imaging, and sputum studies. Mild pulmonary histoplasmosis may not require treatment, but persistent or moderate-to-severe disease is treated with itraconazole or amphotericin B followed by itraconazole. Lung abscesses are typically polymicrobial and treated with beta-lactam/beta-lactamase inhibitors or clindamycin. Voriconazole is first-line therapy for invasive aspergillosis, with surgical debridement considered when feasible. Paragonimiasis is treated with praziquantel or triclabendazole.
Follow-Up and Prognosis
Malignant solitary pulmonary nodules typically double in volume over 20–400 days. Low-risk nodules smaller than 1 cm may be monitored with serial CT imaging, while high-risk nodules should be surgically excised. PET scanning is most useful for nodules larger than 1 cm with intermediate malignancy risk to guide management decisions.
Complications
Untreated lung abscesses may progress to respiratory failure requiring mechanical ventilation. Cavitation may occur in infectious, malignant, and inflammatory nodules, and cavitary lesions are frequently complicated by secondary Aspergillus infection.
