Diagnosis of acute appendicitis: value of unenhanced CT

Two hundred eleven patients with acute pain in the right lower quadrant had CT without oral or IV contrast material. The CT examination required less than 5 min to perform and interpret. We assessed the efficacy of this limited CT examination in identifying patients with acute appendicitis who required emergency laparotomy.

Unenhanced CT of the lower abdomen was performed in 211 patients with lower abdominal pain of uncertain origin (130 women and 81 men 4-91 years old). Scans were obtained by using 10-mm collimation at 10-mm intervals from the L3 level to the symphysis pubis without IV or oral contrast material. Twenty-two to 30 images per patient were obtained, depending on the size of the patient. On average, the entire examination took less than 5 min to complete. Prospective diagnoses based on CT findings were compared with surgical results and clinical follow-up.

Unenhanced CT was an accurate imaging technique for the initial examination of patients with suspected acute appendicitis. The accuracy was 93%. The sensitivity was 87%, the specificity was 97%, the positive predictive value was 94%, and the negative predictive value was 93%.

This study shows that unenhanced CT is a useful test to diagnose appendicitis in patients with acute abdominal pain in the right lower quadrant.