Advantages of focused helical computed tomographic scanning with rectal contrast only vs triple contrast in the diagnosis of clinically uncertain acute appendicitis: a prospective randomized study.

Hypothesis: Focused helical computed tomographic (CT) scanning with rectal contrast only is a superior diagnostic modality compared with the traditional triple-contrast CT scan for the diagnosis of acute appendicitis.

Design: Prospective randomized analysis of both CT scan modalities.

Interventions: Only patients with uncertain diagnosis of acute appendicitis were entered in the study. The patients were then randomized to undergo the traditional triple-contrast CT scan or the new focused CT scan with rectal contrast only. Surgical management included operation or observation for 23 hours.

Results: Ninety-one patients participated in the study, including 52 in the triple-contrast group and 39 in the rectal-contrast group. The demographics of the triple-contrast vs the rectal-contrast groups were similar. The triple-contrast group had a sensitivity of 97%, specificity of 86%, positive predictive value of 90%, and negative predictive value of 93%. The rectal-contrast group had a sensitivity of 88%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 100%. There were 4 false-positive findings and 1 false-negative finding in the triple-contrast group compared with none in the rectal-contrast group. In the triple-contrast group, there were 13 perforated appendixes compared with 1 in the rectal-contrast group. The cost of a triple-contrast scan was 620 US dollars compared with 305 US dollars for a focused rectal-contrast scan. The negative appendectomy rate for the study was 8.0% (4 of 48 patients in the triple-contrast group vs 3 of 39 in the rectal-contrast group).

Conclusions: The demographics, sensitivity, specificity, and positive and negative predictive values were comparable in both groups. The focused rectal-contrast procedure was better tolerated by patients and demonstrated decreased morbidity, delay to diagnosis, perforation rate, and negative appendectomy rate with no missed diagnosis and decreased cost. Therefore, we believe that focused helical CT scanning with rectal contrast only is a superior diagnostic modality compared with the traditional triple-contrast CT scan for the diagnosis of acute appendicitis.