• 
  

  The absence of leukocytosis or the presence of diarrhea does not rule out appendicitis.

  
  
• 
  

  Appendicitis is a clinical diagnosis, with imaging aiding in atypical presentations or cases of diagnostic uncertainty.

  
  
• 
  

  Rapid diagnosis and early surgical intervention help to avoid complications associated with rupture.

  
  
• 
  

  Intravenous antibiotics should be administered if perforation is likely or has occurred.

The lifetime risk of developing acute appendicitis in the United States is 12% for males and 25% for females. Appendicitis is caused by luminal obstruction of the appendix, typically by a fecalith, and less frequently by lymphatic tissue, gallstones, tumors, or parasites. Continued luminal secretion results in increased intraluminal pressure and vascular insufficiency, leading to bacterial proliferation, inflammation, and ultimately perforation.

History

One half of patients present to the emergency department within 24 hours of symptom onset, and another one third present within the following 24 hours. Early on, patients complain of general malaise, indigestion, anorexia, or bowel irregularity. The presence of diarrhea should not be used to exclude appendicitis. The classic patient presentation begins with periumbilical abdominal pain followed by nausea, with or without emesis, and low-grade fever, after which the pain migrates to the right lower quadrant (RLQ) (Table 27-1). Atypical presentations of appendicitis are common. Perforation often results in sudden resolution of pain and should be suspected in patients who present more than 48 hours after symptom onset.

Physical Examination

Patients should receive a complete physical examination, including a pelvic exam for any women of childbearing age. Vague periumbilical abdominal tenderness is observed early in the disease and then migrates to the McBurney point, located one-third of the distance between the right anterior superior iliac spine and the umbilicus. Rebound tenderness and involuntary guarding suggest peritonitis. Rovsing sign, or pain in the RLQ with palpation of the left lower quadrant (LLQ), can also be present. The psoas sign is elicited if abdominal pain is produced with extension of the right leg at the hip while the patient lies on the left side. The obturator test elicits pain with internal and external rotation of the hip. Perforation should be suspected in patients with generalized tenderness, rigidity, or a palpable mass in the RLQ.