Diagnosis of acute appendicitis: value of unenhanced CT.

OBJECTIVE: 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.

SUBJECTS AND METHODS: 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.

RESULTS: 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%.

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