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Emergency and Acute Medicine – Acute Appendicitis
Overview And Definition
Acute appendicitis is the most common surgical abdominal emergency encountered in emergency medicine. It results from acute obstruction of the appendiceal lumen, leading to progressive distension, ischemia, bacterial overgrowth, and eventual perforation if untreated. Pain classically begins in the periumbilical region due to visceral afferent stimulation and later localizes to the right lower quadrant as inflammation involves the parietal peritoneum.
Epidemiology And Special Populations
Children frequently present atypically, with high misdiagnosis rates, especially under 12 years of age, and nearly universal diagnostic difficulty in those under 2 years. Younger children have markedly increased perforation rates, strongly linked to delayed recognition. Older adults often exhibit blunted inflammatory responses and atypical presentations, resulting in higher rates of perforation at diagnosis. In pregnancy, appendicitis occurs most commonly in the second trimester, but perforation risk is greatest in the third trimester. Despite anatomic displacement of the appendix, right lower quadrant pain remains the predominant symptom, and fetal loss increases substantially with perforation.
Pathophysiology And Cause
Luminal obstruction, most commonly from lymphoid hyperplasia or fecaliths, initiates appendiceal distension and venous congestion. Progressive edema compromises arterial flow, allowing bacterial invasion of the wall. Without intervention, perforation typically occurs within 24 to 36 hours and may result in diffuse peritonitis or localized abscess formation. Gram-negative organisms and anaerobes predominate.
Clinical Presentation
Abdominal pain is the hallmark symptom, most often localized to the right lower quadrant, though location varies with appendiceal anatomy. Retrocecal appendicitis may cause flank, back, or testicular pain, while a pelvic appendix may produce suprapubic discomfort or urinary and rectal symptoms. Anorexia is common and often precedes nausea and vomiting. Bowel habit changes, including diarrhea or constipation, may occur. Pediatric patients frequently have vague symptoms, and observation for subtle signs such as reluctance to move, limping, or hip flexion is essential.
Physical Examination
Vital signs may be normal early, with fever typically mild until perforation develops. Localized tenderness at McBurney’s point is common. Guarding may be voluntary early and becomes involuntary as inflammation progresses. Rebound tenderness reflects peritoneal irritation. Provocative signs such as Rovsing, psoas, and obturator maneuvers may aid diagnosis but are less reliable, particularly in children. Rectal examination has limited diagnostic value, while pelvic examination is critical in women to exclude gynecologic pathology.
Diagnostic Approach
A classic history and examination are often sufficient to justify surgical consultation without imaging. In atypical cases, serial examinations combined with selective laboratory and imaging studies reduce unnecessary surgery without increasing perforation risk.
Laboratory And Imaging Evaluation
Leukocytosis with a left shift is common but not universal, and normal values do not exclude appendicitis. C-reactive protein may be helpful, particularly when trended. Urinalysis is usually normal but may show mild abnormalities when the appendix lies near the urinary tract. Ultrasound is preferred in children and pregnancy and demonstrates a noncompressible, enlarged appendix. CT scanning provides the highest diagnostic accuracy and is valuable for identifying complications or alternative diagnoses. MRI offers excellent sensitivity without ionizing radiation and is useful when CT is undesirable.
Differential Diagnosis
Conditions that may mimic appendicitis include gastroenteritis, mesenteric adenitis, Meckel diverticulum, inflammatory bowel disease, diverticulitis, urinary tract infection, gynecologic emergencies, renal colic, testicular torsion, diabetic ketoacidosis, and systemic infections, particularly in pediatric patients.
Emergency Management
Initial management prioritizes airway, breathing, and circulation, with intravenous fluid resuscitation as needed. Patients with strong clinical suspicion require immediate surgical consultation. Adequate analgesia, including opioids, should not be withheld, as it does not obscure diagnostic accuracy. Broad-spectrum antibiotics are administered perioperatively. Selected patients with appendiceal abscess may be managed nonoperatively with antibiotics and drainage, followed by interval appendectomy. Observation with repeat evaluation is appropriate when the diagnosis remains uncertain.
Disposition And Follow-Up
Confirmed appendicitis requires admission for surgical management. Patients with resolving symptoms and low suspicion for appendicitis may be discharged with strict return precautions and reevaluation within 24 to 48 hours.
Clinical Pearls And Pitfalls
Children and older adults often present atypically and have higher perforation rates. Imaging is unnecessary in classic presentations with convincing clinical findings. Appendicitis cannot be definitively excluded solely because the appendix is not visualized on imaging; ongoing clinical reassessment remains essential.
Overview And Definition
Acute appendicitis is the most common surgical abdominal emergency encountered in emergency medicine. It results from acute obstruction of the appendiceal lumen, leading to progressive distension, ischemia, bacterial overgrowth, and eventual perforation if untreated. Pain classically begins in the periumbilical region due to visceral afferent stimulation and later localizes to the right lower quadrant as inflammation involves the parietal peritoneum.
Epidemiology And Special Populations
Children frequently present atypically, with high misdiagnosis rates, especially under 12 years of age, and nearly universal diagnostic difficulty in those under 2 years. Younger children have markedly increased perforation rates, strongly linked to delayed recognition. Older adults often exhibit blunted inflammatory responses and atypical presentations, resulting in higher rates of perforation at diagnosis. In pregnancy, appendicitis occurs most commonly in the second trimester, but perforation risk is greatest in the third trimester. Despite anatomic displacement of the appendix, right lower quadrant pain remains the predominant symptom, and fetal loss increases substantially with perforation.
Pathophysiology And Cause
Luminal obstruction, most commonly from lymphoid hyperplasia or fecaliths, initiates appendiceal distension and venous congestion. Progressive edema compromises arterial flow, allowing bacterial invasion of the wall. Without intervention, perforation typically occurs within 24 to 36 hours and may result in diffuse peritonitis or localized abscess formation. Gram-negative organisms and anaerobes predominate.
Clinical Presentation
Abdominal pain is the hallmark symptom, most often localized to the right lower quadrant, though location varies with appendiceal anatomy. Retrocecal appendicitis may cause flank, back, or testicular pain, while a pelvic appendix may produce suprapubic discomfort or urinary and rectal symptoms. Anorexia is common and often precedes nausea and vomiting. Bowel habit changes, including diarrhea or constipation, may occur. Pediatric patients frequently have vague symptoms, and observation for subtle signs such as reluctance to move, limping, or hip flexion is essential.
Physical Examination
Vital signs may be normal early, with fever typically mild until perforation develops. Localized tenderness at McBurney’s point is common. Guarding may be voluntary early and becomes involuntary as inflammation progresses. Rebound tenderness reflects peritoneal irritation. Provocative signs such as Rovsing, psoas, and obturator maneuvers may aid diagnosis but are less reliable, particularly in children. Rectal examination has limited diagnostic value, while pelvic examination is critical in women to exclude gynecologic pathology.
Diagnostic Approach
A classic history and examination are often sufficient to justify surgical consultation without imaging. In atypical cases, serial examinations combined with selective laboratory and imaging studies reduce unnecessary surgery without increasing perforation risk.
Laboratory And Imaging Evaluation
Leukocytosis with a left shift is common but not universal, and normal values do not exclude appendicitis. C-reactive protein may be helpful, particularly when trended. Urinalysis is usually normal but may show mild abnormalities when the appendix lies near the urinary tract. Ultrasound is preferred in children and pregnancy and demonstrates a noncompressible, enlarged appendix. CT scanning provides the highest diagnostic accuracy and is valuable for identifying complications or alternative diagnoses. MRI offers excellent sensitivity without ionizing radiation and is useful when CT is undesirable.
Differential Diagnosis
Conditions that may mimic appendicitis include gastroenteritis, mesenteric adenitis, Meckel diverticulum, inflammatory bowel disease, diverticulitis, urinary tract infection, gynecologic emergencies, renal colic, testicular torsion, diabetic ketoacidosis, and systemic infections, particularly in pediatric patients.
Emergency Management
Initial management prioritizes airway, breathing, and circulation, with intravenous fluid resuscitation as needed. Patients with strong clinical suspicion require immediate surgical consultation. Adequate analgesia, including opioids, should not be withheld, as it does not obscure diagnostic accuracy. Broad-spectrum antibiotics are administered perioperatively. Selected patients with appendiceal abscess may be managed nonoperatively with antibiotics and drainage, followed by interval appendectomy. Observation with repeat evaluation is appropriate when the diagnosis remains uncertain.
Disposition And Follow-Up
Confirmed appendicitis requires admission for surgical management. Patients with resolving symptoms and low suspicion for appendicitis may be discharged with strict return precautions and reevaluation within 24 to 48 hours.
Clinical Pearls And Pitfalls
Children and older adults often present atypically and have higher perforation rates. Imaging is unnecessary in classic presentations with convincing clinical findings. Appendicitis cannot be definitively excluded solely because the appendix is not visualized on imaging; ongoing clinical reassessment remains essential.
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