Differential Diagnosis for Mimics of Appendicitis

The following differential diagnosis is organized into categories to help guide the thought process:

• Single Most Likely Diagnosis

  • Mesenteric lymphadenitis: This condition is often referred to as the most common mimic of appendicitis, especially in children and young adults. It presents with similar symptoms such as abdominal pain, nausea, and vomiting, but is typically caused by a viral infection and resolves on its own.

• Other Likely Diagnoses

  • Gastroenteritis: Inflammation of the stomach and intestines, usually due to infection, can mimic appendicitis with symptoms like abdominal pain, diarrhea, and vomiting.
  • Ovarian torsion or cyst: These conditions can cause severe abdominal pain and are often considered in the differential diagnosis for appendicitis, especially in female patients.
  • Diverticulitis: Inflammation of a diverticulum in the digestive tract can cause pain, usually on the left side, which might be confused with appendicitis, although the pain location typically differs.
  • Inflammatory bowel disease (IBD): Conditions like Crohn's disease or ulcerative colitis can present with chronic or acute abdominal pain, mimicking appendicitis.

• Do Not Miss Diagnoses

  • Ectopic pregnancy: Although less common, an ectopic pregnancy can present with abdominal pain and must be ruled out, especially in women of childbearing age, as it is a life-threatening condition.
  • Intussusception: A condition where a part of the intestine slides into an adjacent part, which can cause bowel obstruction and ischemia. It's more common in children but can occur in adults.
  • Volvulus: A twisting of a portion of the intestine that can cut off blood flow and lead to tissue death. It's a surgical emergency.
  • Ruptured ovarian cyst: While often not as immediately life-threatening as other conditions, a ruptured ovarian cyst can cause significant pain and internal bleeding.

• Rare Diagnoses

  • Meckel's diverticulitis: Inflammation of a Meckel's diverticulum, a congenital anomaly of the small intestine, can mimic appendicitis.
  • Epiploic appendagitis: Inflammation of an epiploic appendix, a small, fatty protrusion from the colon, can cause abdominal pain similar to appendicitis.
  • Primary epiploic appendagitis: Similar to the previous condition but involves the primary portion of the epiploic appendix.
  • Typhlitis (neutropenic colitis): An inflammation of the cecum that can occur in immunocompromised patients, presenting with right lower quadrant pain.