Clinical Question

Can magnetic resonance imaging (MRI) accurately diagnose acute appendicitis?

Evidence-Based Answer

In pregnant patients, children, and adults with clinical signs and symptoms of appendicitis, MRI has an overall sensitivity of 95% and specificity of 96%. The posttest probability of having appendicitis after a positive MRI is 90% and 2% after a negative MRI, assuming a median pretest probability of 25%.¹ (Strength of Recommendation: B, inconsistent or limited-quality patient-oriented evidence.)

Practice Pointers

Appendicitis is the most common abdominal surgical emergency, leading to more than 300,000 appendectomies in the United States each year.² Timely diagnosis and treatment of acute appendicitis based on clinical findings and radiographic imaging reduce the risk of complications, including perforation, sepsis, peritonitis, and death.³ Ultrasonography is an appropriate option in some circumstances.^4,5 If MRI is accurate in the diagnosis of appendicitis, avoiding ionizing radiation exposure makes it an attractive option, especially in pregnant patients and children. The authors of the Cochrane review sought to assess the accuracy of MRI in diagnosing acute appendicitis in all patients, with subgroup analysis of pregnant patients, children, and adults, as a secondary outcome.