One discussion this week included the rate of negative appendectomy.

Reference: Raja AS, et al. Negative appendectomy rate in the era of CT: an 18-year perspective. Radiology. 2010 Aug;256(2):460-465. doi: 10.1148/radiol.10091570.

Summary: In a retrospective study of records from 1990-2007, researchers from Harvard sought to estimate the correlation between the negative appendectomy rate (NAR) and the rate of preoperative computed tomography (CT) in patients suspected of having acute appendicitis who presented to the emergency department.

The findings showed NAR decreased significantly from 23.0% to 1.7% (P < .0001), the annual number of appendectomies decreased significantly from 217 per year to 119 per year (P = .0003), and the proportion of patients undergoing appendectomy who underwent preoperative CT increased significantly from 1% to 97.5% (P < .0001).

Data from this study also suggest that the use of preoperative CT has been associated with a decrease in the female-to-male NAR ratio from 1.9:1 in 1990 to 0.9:1 in 2007, implying that the use of CT may have been helpful in decreasing the number
of negative appendectomies in women.

(Raja et al, 2010, p.464)