AJR: Pre-op CT decreases negative appendectomy in both sexes

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Negative appendectomy rates can be decreased with the use of preoperative CT in adult men and women, according to a study published in the October issue of the American Journal of Roentgenology. While preoperative CT has been used commonly to reduce the number of negative appendectomies, research has been split over whether or not both sexes benefit from the procedure.

“Although most prior studies have suggested that CT is efficacious only in decreasing the negative appendectomy rate among women, we found that men benefit from CT as well,” wrote Emily M. Webb, MD, and colleagues from the department of radiology at the University of California, San Francisco.

The retrospective study identified 512 patients who had a nonincidental appendectomy between July 2002 and June 2007. Pathology and radiology records were examined to determine whether the patient received a CT scan prior to the operation and whether the appendectomy was eventually determined to be necessary.

Results showed that a majority of patients, 91 percent, underwent preoperative CT, while the rest underwent appendectomy based on clinical findings. Of the patients who underwent CT, 4.7 percent had a negative appendectomy compared with a 12.7 percent negative appendectomy rate for the non-CT group. When broken down by gender, men with preoperative CT and men without had negative appendectomy rates of 2.5 percent and 11.9 percent, respectively.

Prior to the advent of CT, negative appendectomy rates of 20 percent were tolerated in order to avoid missing actual cases of appendicitis, according to the study’s background information. Women had negative appendectomy rates of up to 40 percent, due to gynecologic mimics.

The authors noted that numerous studies have shown consistently that preoperative CT lowers the negative appendectomy rate among women, and speculated this is because a CT helps differentiate between appendicitis and gynecologic disease in women experiencing abdominal pain. Results from Webb et al, however, showed what relatively few studies have shown by demonstrating that men also benefit from CT.

Webb et al did note several limitations to the study. It was a retrospective study from only one institution, and the techniques used were not consistent due to protocol changes and equipment updates. The sample sizes were also small, though the results remained statistically significant in showing benefit for men who underwent preoperative CT prior to an appendectomy.