Acute appendicitis can occur at any age, but most commonly presents in the second and third decade of life. Lifetime incidence is 8.6% in males, 6.7% in females.
Appendicitis results from an obstruction of the appendiceal orifice, which can be caused by a fecalith, lymphoid hyperplasia, infection, calculi, or malignancy. Lymphoid hyperplasia is a more common etiology in younger patients, especially pediatrics.
The hallmark symptoms of appendicitis are anorexia, nausea and emesis, and abdominal pain that radiates or settles in the right lower quadrant (RLQ).
A retrocecal appendicitis may present with dull abdominal pain for a longer duration and may not localize to the RLQ. A positive psoas sign (RLQ pain with passive right hip extension) is more common with this presentation.
Pediatric Patient Considerations:
- Neonates – appendicitis is rare but serious. The most common findings are abdominal distension and/or tenderness, emesis, and poor feeding. Other common findings include lethargy and irritability. There may be delay to diagnosis. Patients may develop sepsis, temperature instability, and dyspnea.
- Young children – appendicitis is infrequent in this population but can occur. The most common findings are abdominal pain (including rebound tenderness and abdominal guarding), fever, and vomiting and anorexia. Diarrhea may occur. The abdomen may or may not be extended. Patients may resist walking or moving about.
- School-age children – appendicitis is more common than in neonates, infants, and young children. Abdominal pain (often right lower quadrant), vomiting, anorexia, and fever are common presenting symptoms. Diarrhea is less frequent than in younger children. Patients may have difficulty walking.
- Adolescents – findings are similar to those of adults with appendicitis.
K35.80 – Unspecified acute appendicitis
85189001 – Acute appendicitis
- Inflammatory bowel disease (eg, Crohn disease, ulcerative colitis)
- Pancreatitis (acute and chronic)
- Meckel diverticulitis
- Acute ileitis (infectious: Yersinia, Campylobacter, Salmonella)
- Pelvic inflammatory disease
- Ectopic pregnancy
- Ruptured ovarian cyst
- Ovarian torsion
- Testicular torsion
- Urolithiasis (see nephrolithiasis, ureteral calculus, urinary bladder calculus)
- Immunoglobulin A vasculitis (formerly Henoch-Schönlein purpura)
- Sickle cell crisis (sickle cell anemia)
- Mesenteric adenitis
Last Updated: 12/14/2018