Update on imaging for acute appendicitis.

Acute appendicitis is a common surgical emergency and the diagnosis can often be made clinically; however, many patients present with atypical findings. For these patients, there are multiple imaging modalities available to aid in the diagnosis of suspected appendicitis in an effort to avoid a negative appendectomy. Computed tomography is the test of choice in most patients in whom the diagnosis is not certain. Ultrasonography is particularly useful in children and pregnant women. Magnetic resonance imaging is recommended when ultrasonography is inconclusive. Appropriate use of these imaging studies avoids delays in treatment, prolonged hospitalization, and unnecessary surgery.