Gastroenterology · Acute Abdomen
The facts most likely to be tested
The classic clinical presentation begins with periumbilical pain that migrates to the right lower quadrant (RLQ) at McBurney's point.
Anorexia is the most consistent symptom, and its absence should prompt consideration of an alternative diagnosis.
McBurney's point tenderness, Rovsing's sign, psoas sign, and obturator sign are the classic physical exam findings used to assess for peritoneal irritation.
CT scan of the abdomen and pelvis with IV contrast is the gold standard diagnostic imaging for adults to confirm the diagnosis.
Graded compression ultrasound is the first-line imaging modality for pregnant patients and children to avoid ionizing radiation.
Appendectomy remains the definitive treatment of choice, though prophylactic antibiotics are required preoperatively to cover gram-negative rods and anaerobes.
Perforation is the most common serious complication, typically presenting with generalized peritonitis and high-grade fever.
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A 22-year-old male presents to the emergency department with a 12-hour history of vague, dull abdominal pain that has now localized to the right lower quadrant. He reports one episode of vomiting and states he has had no appetite since the pain began. On physical exam, he is febrile at 100.8°F. There is marked tenderness at McBurney's point and pain in the right lower quadrant upon palpation of the left lower quadrant.
What is the most likely diagnosis and the most appropriate next step in management?
Acute appendicitis; surgical consultation for appendectomy.
The patient exhibits the classic migration of pain and positive Rovsing's sign, which are highly suggestive of appendicitis; the diagnosis is confirmed via CT scan followed by surgical intervention.
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Etiology / Epidemiology
Most common cause of acute surgical abdomen in patients aged 10-30. Caused by luminal obstruction (fecalith, lymphoid hyperplasia).
Clinical Manifestations
Classic periumbilical to RLQ migration. McBurney's point tenderness and psoas sign are pathognomonic.
Diagnosis
CT abdomen/pelvis with contrast is the gold standard. Diameter >6mm on imaging confirms diagnosis.
Treatment
Appendectomy is definitive. Pre-op cefoxitin or cefotetan are first-line antibiotics.
Prognosis
Perforation risk increases after 24-36 hours. Sepsis and peritonitis are primary mortality drivers.
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Epidemiology & Etiology
Peak incidence occurs in the second and third decades of life. Obstruction is most commonly due to a fecalith in adults or lymphoid hyperplasia following viral infection in children. It remains the most frequent indication for emergency abdominal surgery.
Pertinent Anatomy
The appendix is a vestigial structure attached to the cecum. Its position is variable, but the base is located at McBurney's point, one-third the distance from the anterior superior iliac spine to the umbilicus.
Pathophysiology
Obstruction leads to increased intraluminal pressure, causing venous congestion and ischemia. Bacterial overgrowth ensues, leading to inflammation of the serosa and eventually peritonitis. If untreated, the wall becomes necrotic, leading to perforation and abscess formation.
Clinical Manifestations
Initial symptoms include vague, colicky periumbilical pain that migrates to the RLQ. Physical exam reveals McBurney's point tenderness, Rovsing's sign, psoas sign, and obturator sign. Involuntary guarding and rebound tenderness suggest progression to peritonitis.
Diagnosis
The CT abdomen/pelvis with contrast is the diagnostic modality of choice with >95% sensitivity. Ultrasound is preferred in children or pregnant patients to avoid ionizing radiation. Diagnostic criteria include an appendiceal diameter >6mm and wall thickening.
Treatment
Management requires prompt appendectomy. Pre-operative prophylactic antibiotics covering gram-negative and anaerobic organisms, such as cefoxitin, are mandatory. Do not delay surgery for imaging if clinical presentation is classic, as this increases the risk of perforation.
Prognosis
Early intervention yields excellent outcomes. Complications include intra-abdominal abscess and wound infection. Monitor for fever and leukocytosis post-operatively as indicators of residual infection.
Differential Diagnosis
Mesenteric adenitis: often follows viral URI
Meckel's diverticulum: painless lower GI bleeding
Ectopic pregnancy: positive beta-hCG
Ovarian torsion: sudden onset, severe unilateral pain
Nephrolithiasis: hematuria on urinalysis