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Diagnostic Test – Indium-Labeled Leukocyte Scan
1. How does this test work?
The indium-labeled leukocyte scan is a nuclear medicine study used to detect occult infection or evaluate fever of unknown origin (FUO).
Mechanism:
- A sample of the patient’s blood is drawn.
- White blood cells (leukocytes) are isolated and tagged with radioactive indium.
- The labeled blood is re-injected into the patient.
- The indium-tagged leukocytes migrate and localize to areas of active infection or inflammation.
- Nuclear imaging detects areas of increased uptake, identifying the site of infection.
2. When is an indium scan the right text?
Answer indium-labeled leukocyte scan when you see:
- Occult infection or fever of unknown origin
- Routine studies are negative, such as:
- Blood cultures
- Chest X-ray
- Urinalysis
- Suspicion of infection that is difficult to localize
- Situations where gallium scans are inaccurate, particularly:
- Intra-abdominal infections
3. What is the most accurate test?
- A biopsy of the suspected site of infection is more accurate than an indium-labeled leukocyte scan.
- The indium scan is best used as a localizing tool, guiding further definitive testing.
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Diagnostic Test – Herpes Simplex PCR
1. What is this?
Herpes simplex PCR is a molecular diagnostic test performed on cerebrospinal fluid (CSF).
It detects HSV DNA and is the single most accurate diagnostic test for herpes simplex encephalitis.
2. When is this the correct choice?
Select HSV PCR of the CSF when the clinical scenario includes:
- Fever
- Headache
- Altered mental status or confusion
- Symptom duration less than 2 weeks
Key test-taking point:
- CSF HSV PCR is more accurate than:
- EEG
- Head CT
- Brain MRI
- Even brain biopsy
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Diagnostic Test – Gallium Scanning
1. How does this test work?
Gallium scanning is a nuclear medicine imaging study used to detect infection and certain malignancies.
Mechanism:
2. When is a gallium scan the appropriate choice?
Choose a gallium scan when the clinical picture includes:
1. How does this test work?
Gallium scanning is a nuclear medicine imaging study used to detect infection and certain malignancies.
Mechanism:
- Gallium localizes to areas with:
- Increased white blood cell activity
- Increased iron metabolism
- It is transported in the blood bound to transferrin
- Areas of inflammation, infection, or malignancy show increased gallium uptake
2. When is a gallium scan the appropriate choice?
Choose a gallium scan when the clinical picture includes:
- Persistent fever without localizing symptoms
- Negative initial evaluation, including:
- Blood cultures
- Chest X-ray
- Urinalysis
- Fever of unknown origin (FUO)
- Lymphoma
- Occult abscesses
- A biopsy is the most definitive test following an abnormal gallium scan
- Malignancy → requires histologic confirmation
- Infection → requires culture confirmation
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Emergency and Acute Medicine – Blunt Abdominal Trauma
Overview and Mechanism of Injury
Blunt abdominal trauma results from a sudden transfer of force or pressure to the abdomen. Injury to solid organs most commonly presents with hemorrhage, whereas damage to hollow viscus organs leads to bleeding and peritonitis due to leakage of bowel contents. The clinical impact depends on the magnitude of force, organs involved, and associated injuries.
Etiology and Patterns of Injury
Motor vehicle collisions account for approximately 60% of blunt abdominal trauma cases. Solid organs are injured more often than hollow organs. The spleen is the most frequently affected organ, followed by the liver, intestines, retroperitoneal structures, and kidneys. Less commonly involved structures include the mesentery, pancreas, diaphragm, urinary bladder, urethra, and major vascular structures.
Pediatric Considerations
Children often appear to tolerate blunt trauma better due to the increased elasticity of their tissues. However, because the liver and spleen extend beyond the protective rib cage in children, these organs are more exposed and vulnerable to injury. As a result, significant intra-abdominal injury may occur despite minimal external signs.
Clinical Presentation
Symptoms range widely from mild abdominal discomfort to overt peritoneal irritation and hypovolemic shock. Patients may report nausea or vomiting. Labored breathing can occur due to diaphragmatic irritation or upper abdominal injury. Left shoulder pain during inspiration (Kehr sign) suggests diaphragmatic irritation from intra-abdominal bleeding. Hollow viscus injuries, particularly small-bowel trauma, may present in a delayed fashion.
Initial Evaluation and Essential Workup
Management begins with rapid assessment and stabilization of airway, breathing, and circulation (ABCs). The primary goal is to identify patients who require urgent operative intervention.
A careful abdominal examination should assess for tenderness, distension, guarding, and signs of peritoneal irritation, while recognizing that injuries to the retroperitoneum or intrathoracic abdomen may not be detected by palpation alone. The anatomical boundaries of the abdomen extend from the diaphragm superiorly to the intragluteal folds inferiorly and include the entire circumferential torso.
The skin should be inspected for abrasions or ecchymoses, including the back, which requires rolling the patient. Seatbelt or lap-belt marks are particularly concerning for significant intra-abdominal injury. Bowel sounds may be diminished or absent, although this is a late finding.
A Foley catheter may be placed to monitor urine output if there is no blood at the urethral meatus, no perineal hematoma, and a normal prostate examination. Pelvic radiographs are useful when pelvic fracture or gross hematuria suggests genitourinary injury, prompting further evaluation with specialized imaging when indicated.
Imaging and Diagnostic Modalities
CT scanning is the most valuable tool for evaluating solid organ injury, retroperitoneal structures, and determining the need for surgery, provided the patient is hemodynamically stable enough for transport.
Focused Assessment with Sonography for Trauma (FAST) is a rapid, noninvasive bedside test used to detect free intraperitoneal fluid. While efficient, it is operator dependent.
Diagnostic peritoneal lavage (DPL) is primarily reserved for unstable patients and is especially helpful in identifying injuries within the intrathoracic abdomen, pelvis, or true abdominal cavity. A positive study includes gross blood, elevated red or white blood cell counts, or the presence of bile, feces, or food particles.
Laboratory Evaluation
Initial hemoglobin and hematocrit levels may be normal due to acute isovolemic blood loss. Blood typing and screening are essential, with cross-matching of packed red blood cells for unstable patients. Urinalysis should be performed to detect hematuria, and microscopic hematuria in the setting of shock warrants genitourinary evaluation. Arterial blood gas analysis may reveal a base deficit, indicating hypovolemia and guiding resuscitation efforts.
Differential Diagnosis
Pain from lower thoracic injuries may mimic abdominal pathology and should always be considered in the evaluation of blunt trauma patients.
Prehospital Management
Fluid resuscitation should be titrated to clinical response, with a target systolic blood pressure of 90–100 mm Hg. Normal vital signs do not exclude significant intra-abdominal injury.
Emergency Department Stabilization and Treatment
Initial stabilization focuses on securing the airway, providing high-flow oxygen, and establishing two large-bore intravenous lines for crystalloid infusion. If there is no response after 2 liters of crystalloid, packed red blood cells should be administered. In cases of profound shock, immediate transfusion with O-negative blood may be lifesaving.
A nasogastric tube may be placed to decompress the stomach, reduce distention, and lower aspiration risk, and may improve respiratory distress caused by diaphragmatic herniation of the stomach.
Medications
Tetanus prophylaxis should be administered in patients with open wounds, using tetanus toxoid and tetanus immunoglobulin when indicated. Broad-spectrum intravenous antibiotics with aerobic and anaerobic coverage, such as a second-generation cephalosporin, are recommended when contamination or hollow viscus injury is suspected.
Pediatric Resuscitation Considerations
In children with shock, crystalloid boluses are given at 20 mL/kg, and packed red blood cells are administered at 1 mL/kg when needed.
Disposition and Follow-Up
Admission is indicated for postoperative patients, those with equivocal findings on FAST, CT, or DPL, and for most blunt abdominal trauma cases requiring observation and serial abdominal examinations.
Patients in whom intra-abdominal injury is suspected should not be discharged without an adequate period of observation, even if initial imaging and examination are negative.
Clinical Pearls and Pitfalls
Do not delay blood transfusion in patients with clinical shock despite a normal hematocrit. Avoid excessive crystalloid resuscitation. Always obtain a pregnancy test in females of childbearing age. Unstable patients should never be transported to CT for diagnostic imaging.
Overview and Mechanism of Injury
Blunt abdominal trauma results from a sudden transfer of force or pressure to the abdomen. Injury to solid organs most commonly presents with hemorrhage, whereas damage to hollow viscus organs leads to bleeding and peritonitis due to leakage of bowel contents. The clinical impact depends on the magnitude of force, organs involved, and associated injuries.
Etiology and Patterns of Injury
Motor vehicle collisions account for approximately 60% of blunt abdominal trauma cases. Solid organs are injured more often than hollow organs. The spleen is the most frequently affected organ, followed by the liver, intestines, retroperitoneal structures, and kidneys. Less commonly involved structures include the mesentery, pancreas, diaphragm, urinary bladder, urethra, and major vascular structures.
Pediatric Considerations
Children often appear to tolerate blunt trauma better due to the increased elasticity of their tissues. However, because the liver and spleen extend beyond the protective rib cage in children, these organs are more exposed and vulnerable to injury. As a result, significant intra-abdominal injury may occur despite minimal external signs.
Clinical Presentation
Symptoms range widely from mild abdominal discomfort to overt peritoneal irritation and hypovolemic shock. Patients may report nausea or vomiting. Labored breathing can occur due to diaphragmatic irritation or upper abdominal injury. Left shoulder pain during inspiration (Kehr sign) suggests diaphragmatic irritation from intra-abdominal bleeding. Hollow viscus injuries, particularly small-bowel trauma, may present in a delayed fashion.
Initial Evaluation and Essential Workup
Management begins with rapid assessment and stabilization of airway, breathing, and circulation (ABCs). The primary goal is to identify patients who require urgent operative intervention.
A careful abdominal examination should assess for tenderness, distension, guarding, and signs of peritoneal irritation, while recognizing that injuries to the retroperitoneum or intrathoracic abdomen may not be detected by palpation alone. The anatomical boundaries of the abdomen extend from the diaphragm superiorly to the intragluteal folds inferiorly and include the entire circumferential torso.
The skin should be inspected for abrasions or ecchymoses, including the back, which requires rolling the patient. Seatbelt or lap-belt marks are particularly concerning for significant intra-abdominal injury. Bowel sounds may be diminished or absent, although this is a late finding.
A Foley catheter may be placed to monitor urine output if there is no blood at the urethral meatus, no perineal hematoma, and a normal prostate examination. Pelvic radiographs are useful when pelvic fracture or gross hematuria suggests genitourinary injury, prompting further evaluation with specialized imaging when indicated.
Imaging and Diagnostic Modalities
CT scanning is the most valuable tool for evaluating solid organ injury, retroperitoneal structures, and determining the need for surgery, provided the patient is hemodynamically stable enough for transport.
Focused Assessment with Sonography for Trauma (FAST) is a rapid, noninvasive bedside test used to detect free intraperitoneal fluid. While efficient, it is operator dependent.
Diagnostic peritoneal lavage (DPL) is primarily reserved for unstable patients and is especially helpful in identifying injuries within the intrathoracic abdomen, pelvis, or true abdominal cavity. A positive study includes gross blood, elevated red or white blood cell counts, or the presence of bile, feces, or food particles.
Laboratory Evaluation
Initial hemoglobin and hematocrit levels may be normal due to acute isovolemic blood loss. Blood typing and screening are essential, with cross-matching of packed red blood cells for unstable patients. Urinalysis should be performed to detect hematuria, and microscopic hematuria in the setting of shock warrants genitourinary evaluation. Arterial blood gas analysis may reveal a base deficit, indicating hypovolemia and guiding resuscitation efforts.
Differential Diagnosis
Pain from lower thoracic injuries may mimic abdominal pathology and should always be considered in the evaluation of blunt trauma patients.
Prehospital Management
Fluid resuscitation should be titrated to clinical response, with a target systolic blood pressure of 90–100 mm Hg. Normal vital signs do not exclude significant intra-abdominal injury.
Emergency Department Stabilization and Treatment
Initial stabilization focuses on securing the airway, providing high-flow oxygen, and establishing two large-bore intravenous lines for crystalloid infusion. If there is no response after 2 liters of crystalloid, packed red blood cells should be administered. In cases of profound shock, immediate transfusion with O-negative blood may be lifesaving.
A nasogastric tube may be placed to decompress the stomach, reduce distention, and lower aspiration risk, and may improve respiratory distress caused by diaphragmatic herniation of the stomach.
Medications
Tetanus prophylaxis should be administered in patients with open wounds, using tetanus toxoid and tetanus immunoglobulin when indicated. Broad-spectrum intravenous antibiotics with aerobic and anaerobic coverage, such as a second-generation cephalosporin, are recommended when contamination or hollow viscus injury is suspected.
Pediatric Resuscitation Considerations
In children with shock, crystalloid boluses are given at 20 mL/kg, and packed red blood cells are administered at 1 mL/kg when needed.
Disposition and Follow-Up
Admission is indicated for postoperative patients, those with equivocal findings on FAST, CT, or DPL, and for most blunt abdominal trauma cases requiring observation and serial abdominal examinations.
Patients in whom intra-abdominal injury is suspected should not be discharged without an adequate period of observation, even if initial imaging and examination are negative.
Clinical Pearls and Pitfalls
Do not delay blood transfusion in patients with clinical shock despite a normal hematocrit. Avoid excessive crystalloid resuscitation. Always obtain a pregnancy test in females of childbearing age. Unstable patients should never be transported to CT for diagnostic imaging.
- Published on
Diagnostic Tests – Tzanck Smear
1. What is this?
A Tzanck smear is a cytologic test used to evaluate vesicular skin or mucosal lesions. Cells are scraped from the base of a vesicle, stained, and examined under a microscope. The key finding is the presence of multinucleated giant cells, which are characteristic of herpetic infections.
Importantly, the Tzanck smear cannot distinguish between:
- Herpes simplex virus (HSV)
- Varicella-zoster virus (VZV)
You should answer Tzanck smear as the best initial diagnostic test when:
- A patient presents with vesicular skin or genital lesions
- A herpetic infection (HSV or VZV) is suspected
- The diagnosis is not clinically obvious
Vesicles + possible herpes → Tzanck smear first
If the classic clustered vesicles on an erythematous base are clearly present, testing may not be necessary.
3. What is the most accurate diagnostic test?
The most accurate diagnostic test for herpetic skin or genital infections is a:
- Viral culture
High-yield Summary
- Tzanck smear → quick, bedside, shows multinucleated giant cells
- Cannot differentiate HSV vs VZV
- Gold standard → viral culture
- Published on
Diagnostic Test – Legionella Urine Antigen
1. What is this?
The Legionella urine antigen test detects antigen from Legionella pneumophila in the urine. It is a rapid, noninvasive test and is considered the best initial test to make a specific diagnosis of Legionella pneumonia.
2. What is the best test?
Choose Legionella urine antigen when the clinical scenario shows:
1. What is this?
The Legionella urine antigen test detects antigen from Legionella pneumophila in the urine. It is a rapid, noninvasive test and is considered the best initial test to make a specific diagnosis of Legionella pneumonia.
2. What is the best test?
- The urine antigen test has ~100% specificity for Legionella pneumophila serogroup 1.
- However, only 70–80% of Legionella infections are caused by serogroup 1.
- Therefore, the definitive diagnostic test is:
- Sputum culture or tracheal aspirate culture on buffered charcoal yeast extract (BCYE) agar.
Choose Legionella urine antigen when the clinical scenario shows:
- Pneumonia in a nursing home resident or recent hospitalization
- High fever
- Confusion
- Diarrhea
- Hyponatremia
- Possible lab abnormalities:
- ↑ Creatine phosphokinase (CPK)
- ↑ Liver function tests
- ↑ Creatinine
- Published on
Diagnostic Test – Monospot Test
1. What is this?
The Monospot test is the best initial screening test used to diagnose infectious mononucleosis (IM).
It detects heterophile antibodies, which are characteristically produced during infection with Epstein–Barr virus (EBV).
2. When do you answer Monospot test?
Answer Monospot test when the clinical vignette describes:
- Sore throat
- Fever
- Lymphadenopathy (especially posterior cervical)
- Malaise and fatigue
- Splenomegaly (present in ~50% of patients)
- Exudative pharyngitis (may be present)
- Rash occurs in ~15% of cases normally
- Rash in ~90% of patients if ampicillin or amoxicillin is given
3. What is the most accurate test?
- The most accurate test in the acute phase is:
- IgM antibody to EBV viral capsid antigen (VCA)
- EBV nuclear antigen (EBNA) antibodies appear later, usually 3–4 weeks after infection, and are not useful for acute diagnosis
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Emergency and Acute Medicine – Evaluation and Management of Abdominal Pain
Overview and Pain Mechanisms
Abdominal pain originates from several distinct physiologic processes. Parietal pain occurs when the peritoneum becomes inflamed by irritating substances. It is conveyed through somatic nerves, intensifies with movement or changes in abdominal wall tension, and is typically sharp, well defined, and associated with rebound tenderness and involuntary guarding.
In contrast, visceral pain arises from internal organs and is transmitted through autonomic afferent pathways. This pain is often vague and poorly localized, reflecting embryologic origin rather than precise anatomy. Pain from foregut organs is perceived in the epigastrium, midgut pain around the umbilicus, and hindgut pain in the suprapubic region. It commonly results from distention of hollow organs, stretching of organ capsules, or smooth muscle spasm, and may be constant or colicky.
As inflammation progresses and involves the parietal peritoneum, localized tenderness develops. Ischemic pain, frequently due to vascular emergencies, is characteristically severe and diffuse. Referred pain is experienced at a site distant from the affected organ because of shared neural pathways. Abdominal wall pain is usually persistent and aching, often accompanied by muscle spasm and involvement of nearby muscle groups.
Causes of Abdominal Pain
Etiologies are broad and include peritoneal irritation from gastric acid, fecal contamination, pus, blood, bile, or pancreatic enzymes. Obstructive processes may affect the small or large bowel, gallbladder, ureters, or kidneys, and may be complicated by ischemia of intestinal, renal, or splenic tissue. Inflammatory conditions include appendicitis, inflammatory bowel disease, cholecystitis, hepatitis, peptic ulcer disease, pancreatitis, pelvic inflammatory disease, and pyelonephritis. Additional considerations include abdominal wall pathology and referred pain from extra-abdominal sources such as intrathoracic disease.
Clinical Assessment: History and Symptoms
A thorough history is critical. Important features include the onset, timing, duration, and progression of pain; its initial and current location; radiation; and quality (sharp, dull, cramping). Clinicians should assess aggravating and relieving factors and associated symptoms such as anorexia, nausea, vomiting (including bilious or coffee-ground material), malaise, syncope, respiratory complaints, changes in bowel habits or stool color, hematuria, urinary symptoms, trauma, gynecologic or obstetric history, recent surgery, family history of vascular disease, alcohol intake, and medication use, particularly NSAIDs or aspirin.
Physical Examination Findings
General examination may reveal fever, tachycardia, tachypnea, hypotension, jaundice, or abnormal peripheral pulses. Abdominal evaluation should include inspection for distension, auscultation for altered bowel sounds, and palpation for masses or tenderness. Signs of peritoneal irritation such as guarding and rebound tenderness are key. Specific maneuvers—including Rovsing, psoas, obturator, McBurney point tenderness, Murphy sign, and Carnett sign—help localize pathology. Rectal and pelvic examinations may identify tenderness, masses, cervical motion tenderness, or occult blood. Genitourinary assessment includes evaluation for flank pain, dysuria, costovertebral angle tenderness, testicular pain, and suprapubic tenderness. Skin findings such as jaundice, ecchymosis, rashes, or vesicular lesions may provide diagnostic clues.
Initial Workup
Pregnancy testing is mandatory in women of reproductive age. In many cases, ultrasonography serves as the first-line imaging study, with CT scanning reserved for situations in which ultrasound is nondiagnostic or when more detailed evaluation is required.
Investigations and Interpretation
Laboratory studies typically include a complete blood count, serum electrolytes, renal function tests, glucose, inflammatory markers, liver function tests, lactic acid, serum lipase, urinalysis, stool studies when indicated, and pregnancy testing.
Imaging is guided by clinical suspicion and may include ECG for possible cardiac causes, abdominal radiographs, upright chest radiograph to assess for free air, ultrasonography for biliary disease, hydronephrosis, free fluid, aneurysm, or torsion, and CT scanning tailored to suspected pathology. CT angiography is essential when mesenteric ischemia or abdominal aortic aneurysm is suspected. MRI may be considered when radiation exposure or contrast nephrotoxicity is a concern.
Differential Diagnosis
Abdominal pain encompasses a wide differential including gastrointestinal, vascular, genitourinary, gynecologic, metabolic, infectious, and referred causes. Examples include bowel obstruction, appendicitis, cholecystitis, pancreatitis, diverticulitis, ectopic pregnancy, ovarian torsion, renal colic, ischemic bowel, myocardial infarction, pneumonia, abdominal wall disorders, and herpes zoster. Pediatric considerations vary by age and include intussusception, volvulus, incarcerated hernia, Meckel diverticulitis, and sickle cell crisis.
Management in the Emergency Department
Initial management focuses on stabilization and symptom control. This includes bowel rest, nasogastric decompression when indicated, intravenous fluids, correction of electrolyte abnormalities, and antiemetics. Adequate analgesia should be provided promptly and not delayed. Blood typing and cross-matching are required in unstable patients, and early surgical consultation is crucial when a surgical cause is suspected.
Pharmacologic Therapy
Pain control commonly involves opioids such as fentanyl or morphine. Nausea and vomiting are treated with antiemetics including ondansetron, prochlorperazine, or promethazine.
Disposition and Follow-Up
Hospital admission is indicated for patients with suspected surgical pathology, peritoneal signs, inability to tolerate oral intake, uncontrolled pain, serious medical causes such as myocardial infarction or diabetic ketoacidosis, or the need for intravenous antibiotics.
Discharge may be appropriate when serious pathology has been excluded, pain is well controlled, oral intake is tolerated, and the patient can comply with clear return instructions.
Discharge Advice and Safety Netting
Patients should be advised to return immediately for worsening or persistent pain, ongoing vomiting, blood in vomitus or stool, jaundice, fever or chills, or lack of improvement within 8–12 hours.
Clinical Pearls
Older adults often present atypically and are at higher risk for life-threatening conditions. Constipation should not be diagnosed solely by the absence of stool in the rectum. When vomiting precedes the onset of abdominal pain, a surgical cause is less likely.
Overview and Pain Mechanisms
Abdominal pain originates from several distinct physiologic processes. Parietal pain occurs when the peritoneum becomes inflamed by irritating substances. It is conveyed through somatic nerves, intensifies with movement or changes in abdominal wall tension, and is typically sharp, well defined, and associated with rebound tenderness and involuntary guarding.
In contrast, visceral pain arises from internal organs and is transmitted through autonomic afferent pathways. This pain is often vague and poorly localized, reflecting embryologic origin rather than precise anatomy. Pain from foregut organs is perceived in the epigastrium, midgut pain around the umbilicus, and hindgut pain in the suprapubic region. It commonly results from distention of hollow organs, stretching of organ capsules, or smooth muscle spasm, and may be constant or colicky.
As inflammation progresses and involves the parietal peritoneum, localized tenderness develops. Ischemic pain, frequently due to vascular emergencies, is characteristically severe and diffuse. Referred pain is experienced at a site distant from the affected organ because of shared neural pathways. Abdominal wall pain is usually persistent and aching, often accompanied by muscle spasm and involvement of nearby muscle groups.
Causes of Abdominal Pain
Etiologies are broad and include peritoneal irritation from gastric acid, fecal contamination, pus, blood, bile, or pancreatic enzymes. Obstructive processes may affect the small or large bowel, gallbladder, ureters, or kidneys, and may be complicated by ischemia of intestinal, renal, or splenic tissue. Inflammatory conditions include appendicitis, inflammatory bowel disease, cholecystitis, hepatitis, peptic ulcer disease, pancreatitis, pelvic inflammatory disease, and pyelonephritis. Additional considerations include abdominal wall pathology and referred pain from extra-abdominal sources such as intrathoracic disease.
Clinical Assessment: History and Symptoms
A thorough history is critical. Important features include the onset, timing, duration, and progression of pain; its initial and current location; radiation; and quality (sharp, dull, cramping). Clinicians should assess aggravating and relieving factors and associated symptoms such as anorexia, nausea, vomiting (including bilious or coffee-ground material), malaise, syncope, respiratory complaints, changes in bowel habits or stool color, hematuria, urinary symptoms, trauma, gynecologic or obstetric history, recent surgery, family history of vascular disease, alcohol intake, and medication use, particularly NSAIDs or aspirin.
Physical Examination Findings
General examination may reveal fever, tachycardia, tachypnea, hypotension, jaundice, or abnormal peripheral pulses. Abdominal evaluation should include inspection for distension, auscultation for altered bowel sounds, and palpation for masses or tenderness. Signs of peritoneal irritation such as guarding and rebound tenderness are key. Specific maneuvers—including Rovsing, psoas, obturator, McBurney point tenderness, Murphy sign, and Carnett sign—help localize pathology. Rectal and pelvic examinations may identify tenderness, masses, cervical motion tenderness, or occult blood. Genitourinary assessment includes evaluation for flank pain, dysuria, costovertebral angle tenderness, testicular pain, and suprapubic tenderness. Skin findings such as jaundice, ecchymosis, rashes, or vesicular lesions may provide diagnostic clues.
Initial Workup
Pregnancy testing is mandatory in women of reproductive age. In many cases, ultrasonography serves as the first-line imaging study, with CT scanning reserved for situations in which ultrasound is nondiagnostic or when more detailed evaluation is required.
Investigations and Interpretation
Laboratory studies typically include a complete blood count, serum electrolytes, renal function tests, glucose, inflammatory markers, liver function tests, lactic acid, serum lipase, urinalysis, stool studies when indicated, and pregnancy testing.
Imaging is guided by clinical suspicion and may include ECG for possible cardiac causes, abdominal radiographs, upright chest radiograph to assess for free air, ultrasonography for biliary disease, hydronephrosis, free fluid, aneurysm, or torsion, and CT scanning tailored to suspected pathology. CT angiography is essential when mesenteric ischemia or abdominal aortic aneurysm is suspected. MRI may be considered when radiation exposure or contrast nephrotoxicity is a concern.
Differential Diagnosis
Abdominal pain encompasses a wide differential including gastrointestinal, vascular, genitourinary, gynecologic, metabolic, infectious, and referred causes. Examples include bowel obstruction, appendicitis, cholecystitis, pancreatitis, diverticulitis, ectopic pregnancy, ovarian torsion, renal colic, ischemic bowel, myocardial infarction, pneumonia, abdominal wall disorders, and herpes zoster. Pediatric considerations vary by age and include intussusception, volvulus, incarcerated hernia, Meckel diverticulitis, and sickle cell crisis.
Management in the Emergency Department
Initial management focuses on stabilization and symptom control. This includes bowel rest, nasogastric decompression when indicated, intravenous fluids, correction of electrolyte abnormalities, and antiemetics. Adequate analgesia should be provided promptly and not delayed. Blood typing and cross-matching are required in unstable patients, and early surgical consultation is crucial when a surgical cause is suspected.
Pharmacologic Therapy
Pain control commonly involves opioids such as fentanyl or morphine. Nausea and vomiting are treated with antiemetics including ondansetron, prochlorperazine, or promethazine.
Disposition and Follow-Up
Hospital admission is indicated for patients with suspected surgical pathology, peritoneal signs, inability to tolerate oral intake, uncontrolled pain, serious medical causes such as myocardial infarction or diabetic ketoacidosis, or the need for intravenous antibiotics.
Discharge may be appropriate when serious pathology has been excluded, pain is well controlled, oral intake is tolerated, and the patient can comply with clear return instructions.
Discharge Advice and Safety Netting
Patients should be advised to return immediately for worsening or persistent pain, ongoing vomiting, blood in vomitus or stool, jaundice, fever or chills, or lack of improvement within 8–12 hours.
Clinical Pearls
Older adults often present atypically and are at higher risk for life-threatening conditions. Constipation should not be diagnosed solely by the absence of stool in the rectum. When vomiting precedes the onset of abdominal pain, a surgical cause is less likely.
- Published on
Emergency and Acute Medicine – Abdominal Aortic Aneurysm (AAA)
Overview and Definition
An abdominal aortic aneurysm is defined as a focal dilation of the abdominal aorta with an increase in diameter of at least 50%, most commonly exceeding 3 cm. Approximately 95% of aneurysms are located below the renal arteries. The majority remain clinically silent until rapid enlargement or rupture occurs. Rupture may extend into either the retroperitoneal or intraperitoneal space; intraperitoneal rupture is usually catastrophic and often immediately fatal. Average aneurysm growth is approximately 0.2–0.5 cm per year. Overall mortality following rupture approaches 90%, remaining high even among patients who reach the hospital and those who undergo emergency surgical repair.
Epidemiology and Geriatric Considerations
The risk of AAA increases significantly with age. It is present in 4–8% of individuals older than 65 years and is more common in men. Prevalence rises further in advanced age groups. Although less common in women, aneurysms in women rupture more frequently and at smaller diameters compared with men.
Etiology and Risk Factors
Major risk factors include male sex, age over 65 years, cigarette smoking, family history, atherosclerosis, hypertension, and diabetes mellitus. Inherited connective tissue disorders such as Ehlers–Danlos syndrome and Marfan syndrome also increase susceptibility. Less common causes include blunt abdominal trauma, congenital aneurysms, and infectious involvement of the aorta, including mycotic aneurysms associated with endocarditis.
Rupture risk is strongly related to aneurysm size and growth rate. Larger aneurysms have progressively higher annual rupture rates, and rapid expansion—greater than 0.5 cm within six months—signals a high risk of rupture. Women have up to a fourfold increased rupture risk compared with men for aneurysms of similar size.
Clinical Presentation
Most unruptured aneurysms are asymptomatic and discovered incidentally. When symptoms occur, patients may complain of abdominal, back, or flank pain that is vague, dull, constant, throbbing, or colicky. Pain may radiate to the chest, groin, thigh, inguinal region, or scrotum. Some patients experience lower extremity pain, syncope, or near-syncope.
Ruptured AAA may present with the classic triad of abdominal or back pain, hypotension, and a pulsatile abdominal mass, although all three findings are present in only a minority of cases. Additional findings include tachycardia, signs of shock, flank ecchymosis indicating retroperitoneal hemorrhage, abdominal tenderness, abdominal bruit, gastrointestinal bleeding, and diminished or asymmetric lower-extremity pulses. Complications include thromboembolism causing acute limb ischemia, microemboli resulting in “blue toe syndrome,” and aortoenteric fistula presenting with gastrointestinal hemorrhage.
Initial Assessment and Essential Workup
Evaluation is dictated by hemodynamic stability. Unstable patients require immediate bedside abdominal ultrasonography to rapidly identify an aneurysm, followed by urgent operative intervention without delay for further testing. Stable but symptomatic patients should undergo abdominal CT imaging to confirm the diagnosis, assess aneurysm size, and identify rupture location. Diagnostic studies must never delay definitive surgical management when rupture is suspected.
Diagnostic Tests and Interpretation
Laboratory evaluation includes complete blood count, renal function tests, coagulation studies, urinalysis, and immediate blood typing and cross-matching.
Plain abdominal or lumbar radiographs may show curvilinear calcification of the aortic wall or a paravertebral soft-tissue mass but cannot reliably detect rupture and should not be used to exclude the diagnosis.
Ultrasonography is highly sensitive and specific for detecting AAA prior to rupture and is the imaging modality of choice in unstable patients, though sensitivity decreases once rupture has occurred.
CT scanning provides accurate measurement of aneurysm diameter, identifies rupture location, and guides operative planning. CT angiography is required when endovascular repair is being considered.
Differential Diagnosis
The differential diagnosis includes aortic dissection, renal or biliary colic, pancreatitis, cholecystitis, appendicitis, bowel obstruction, perforated viscus, mesenteric ischemia, diverticulitis, gastrointestinal hemorrhage, myocardial infarction, sepsis, adrenal crisis, spinal cord compression, and other abdominal arterial aneurysms.
Prehospital and Emergency Department Management
Prehospital care focuses on rapid recognition, establishment of two large-bore intravenous lines, and expedited transport to a facility with surgical capability. Early notification allows preparation of the operating room, blood products, and vascular surgery consultation.
In the emergency department, management includes cardiac monitoring, cautious crystalloid infusion, and early blood transfusion. Excessive fluid resuscitation should be avoided, as it may increase bleeding before surgical control. Once symptomatic AAA is suspected, emergent vascular surgery consultation and definitive operative repair—open or endovascular—are mandatory.
Disposition and Follow-Up
All patients with symptomatic AAA require immediate surgical intervention and hospital admission. Asymptomatic patients may be discharged only with reliable outpatient vascular surgery follow-up.
Discharge Instructions and Safety Netting
Patients should be instructed to seek immediate medical attention for new or worsening pain in the abdomen, back, flank, or lower extremities, as well as dizziness or syncope.
Clinical Pearls and Pitfalls
AAA must be considered in any patient presenting with abdominal, back, or flank pain, particularly older adults and smokers. Symptomatic aneurysms represent true surgical emergencies, and definitive care should never be delayed for additional diagnostic studies. Hemodynamically unstable patients should not be sent for CT imaging.
Overview and Definition
An abdominal aortic aneurysm is defined as a focal dilation of the abdominal aorta with an increase in diameter of at least 50%, most commonly exceeding 3 cm. Approximately 95% of aneurysms are located below the renal arteries. The majority remain clinically silent until rapid enlargement or rupture occurs. Rupture may extend into either the retroperitoneal or intraperitoneal space; intraperitoneal rupture is usually catastrophic and often immediately fatal. Average aneurysm growth is approximately 0.2–0.5 cm per year. Overall mortality following rupture approaches 90%, remaining high even among patients who reach the hospital and those who undergo emergency surgical repair.
Epidemiology and Geriatric Considerations
The risk of AAA increases significantly with age. It is present in 4–8% of individuals older than 65 years and is more common in men. Prevalence rises further in advanced age groups. Although less common in women, aneurysms in women rupture more frequently and at smaller diameters compared with men.
Etiology and Risk Factors
Major risk factors include male sex, age over 65 years, cigarette smoking, family history, atherosclerosis, hypertension, and diabetes mellitus. Inherited connective tissue disorders such as Ehlers–Danlos syndrome and Marfan syndrome also increase susceptibility. Less common causes include blunt abdominal trauma, congenital aneurysms, and infectious involvement of the aorta, including mycotic aneurysms associated with endocarditis.
Rupture risk is strongly related to aneurysm size and growth rate. Larger aneurysms have progressively higher annual rupture rates, and rapid expansion—greater than 0.5 cm within six months—signals a high risk of rupture. Women have up to a fourfold increased rupture risk compared with men for aneurysms of similar size.
Clinical Presentation
Most unruptured aneurysms are asymptomatic and discovered incidentally. When symptoms occur, patients may complain of abdominal, back, or flank pain that is vague, dull, constant, throbbing, or colicky. Pain may radiate to the chest, groin, thigh, inguinal region, or scrotum. Some patients experience lower extremity pain, syncope, or near-syncope.
Ruptured AAA may present with the classic triad of abdominal or back pain, hypotension, and a pulsatile abdominal mass, although all three findings are present in only a minority of cases. Additional findings include tachycardia, signs of shock, flank ecchymosis indicating retroperitoneal hemorrhage, abdominal tenderness, abdominal bruit, gastrointestinal bleeding, and diminished or asymmetric lower-extremity pulses. Complications include thromboembolism causing acute limb ischemia, microemboli resulting in “blue toe syndrome,” and aortoenteric fistula presenting with gastrointestinal hemorrhage.
Initial Assessment and Essential Workup
Evaluation is dictated by hemodynamic stability. Unstable patients require immediate bedside abdominal ultrasonography to rapidly identify an aneurysm, followed by urgent operative intervention without delay for further testing. Stable but symptomatic patients should undergo abdominal CT imaging to confirm the diagnosis, assess aneurysm size, and identify rupture location. Diagnostic studies must never delay definitive surgical management when rupture is suspected.
Diagnostic Tests and Interpretation
Laboratory evaluation includes complete blood count, renal function tests, coagulation studies, urinalysis, and immediate blood typing and cross-matching.
Plain abdominal or lumbar radiographs may show curvilinear calcification of the aortic wall or a paravertebral soft-tissue mass but cannot reliably detect rupture and should not be used to exclude the diagnosis.
Ultrasonography is highly sensitive and specific for detecting AAA prior to rupture and is the imaging modality of choice in unstable patients, though sensitivity decreases once rupture has occurred.
CT scanning provides accurate measurement of aneurysm diameter, identifies rupture location, and guides operative planning. CT angiography is required when endovascular repair is being considered.
Differential Diagnosis
The differential diagnosis includes aortic dissection, renal or biliary colic, pancreatitis, cholecystitis, appendicitis, bowel obstruction, perforated viscus, mesenteric ischemia, diverticulitis, gastrointestinal hemorrhage, myocardial infarction, sepsis, adrenal crisis, spinal cord compression, and other abdominal arterial aneurysms.
Prehospital and Emergency Department Management
Prehospital care focuses on rapid recognition, establishment of two large-bore intravenous lines, and expedited transport to a facility with surgical capability. Early notification allows preparation of the operating room, blood products, and vascular surgery consultation.
In the emergency department, management includes cardiac monitoring, cautious crystalloid infusion, and early blood transfusion. Excessive fluid resuscitation should be avoided, as it may increase bleeding before surgical control. Once symptomatic AAA is suspected, emergent vascular surgery consultation and definitive operative repair—open or endovascular—are mandatory.
Disposition and Follow-Up
All patients with symptomatic AAA require immediate surgical intervention and hospital admission. Asymptomatic patients may be discharged only with reliable outpatient vascular surgery follow-up.
Discharge Instructions and Safety Netting
Patients should be instructed to seek immediate medical attention for new or worsening pain in the abdomen, back, flank, or lower extremities, as well as dizziness or syncope.
Clinical Pearls and Pitfalls
AAA must be considered in any patient presenting with abdominal, back, or flank pain, particularly older adults and smokers. Symptomatic aneurysms represent true surgical emergencies, and definitive care should never be delayed for additional diagnostic studies. Hemodynamically unstable patients should not be sent for CT imaging.
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Diagnostic Tests – Polymerase Chain Reaction (PCR) HIV RNA Viral Load
1. What is this?
The PCR HIV RNA viral load test is a quantitative blood test that measures the amount of HIV RNA circulating in the bloodstream. It directly reflects the level of viral replication and is one of the most important tools for monitoring HIV infection.
2. When this test is mentioned, what should you think of?
When you see PCR HIV RNA viral load, think disease activity and treatment response:
• It is the first parameter to change after starting effective antiretroviral therapy (ART)
• It is also the earliest indicator of treatment failure or nonadherence
• Viral load predicts the rate of CD4 (T-helper cell) decline
• High viral load → rapid disease progression
• Low or undetectable viral load → slower progression and effective therapy
Exam pearl:
Viral load changes before CD4 count does.
3. When do you answer PCR HIV RNA viral load?
You should select PCR HIV RNA viral load testing in the following situations:
• At the time of initial HIV diagnosis
• Every 3–4 months to monitor response to therapy
• When treatment failure is suspected
• When performing HIV resistance (sensitivity) testing, as viral load measurement is required to assess resistance in a failing regimen
High-yield summary
• Best test for monitoring treatment response → PCR HIV RNA viral load
• Best predictor of disease progression → PCR HIV RNA viral load
• Diagnosis of HIV → antibody/antigen testing (not viral load)
1. What is this?
The PCR HIV RNA viral load test is a quantitative blood test that measures the amount of HIV RNA circulating in the bloodstream. It directly reflects the level of viral replication and is one of the most important tools for monitoring HIV infection.
2. When this test is mentioned, what should you think of?
When you see PCR HIV RNA viral load, think disease activity and treatment response:
• It is the first parameter to change after starting effective antiretroviral therapy (ART)
• It is also the earliest indicator of treatment failure or nonadherence
• Viral load predicts the rate of CD4 (T-helper cell) decline
• High viral load → rapid disease progression
• Low or undetectable viral load → slower progression and effective therapy
Exam pearl:
Viral load changes before CD4 count does.
3. When do you answer PCR HIV RNA viral load?
You should select PCR HIV RNA viral load testing in the following situations:
• At the time of initial HIV diagnosis
• Every 3–4 months to monitor response to therapy
• When treatment failure is suspected
• When performing HIV resistance (sensitivity) testing, as viral load measurement is required to assess resistance in a failing regimen
High-yield summary
• Best test for monitoring treatment response → PCR HIV RNA viral load
• Best predictor of disease progression → PCR HIV RNA viral load
• Diagnosis of HIV → antibody/antigen testing (not viral load)
