Younger Women with Suspected Appendicitis Benefit from Preoperative CT Imaging

Coursey, M.D., a radiologist at Emory University (Atlanta, GA, USA), who coauthored this study, published in the February 2010 issue of the journal Radiology, while a radiology fellow at Duke University Medical Center (Durham, NC, USA).

Acute appendicitis is inflammation of the appendix, which can perforate, resulting in a life-threatening infection. While surgical removal of the appendix is the common treatment for acute appendicitis, diagnosis is not always clinically obvious. Before the advent of CT, in inconclusive cases, physicians would often remove the appendix as a precaution. Historically, this resulted in a high rate of negative appendectomies with negative appendectomy rates of 20-25% and as high as 40% in women considered acceptable. Negative appendectomy rates are typically higher in women due to gynecologic pathology that can confound appendicitis diagnosis. For instance, symptomatic ovarian cysts can cause lower abdominal pain similar to that from appendicitis.

CT is now frequently used in the assessment of suspected appendicitis and has the potential to reduce the negative appendectomy rate. An acutely inflamed appendix appears thick-walled on a CT image, and adjacent inflammatory changes are often visible. If the appendix is perforated, fluid next to the appendix may be visible on CT.

There have been contradictory reports in the medical literature regarding whether or not the increased use of CT has resulted in a lower negative appendectomy rate. To determine the impact of CT imaging on negative appendectomy rates, Dr. Coursey and colleagues reviewed a surgical database of 925 patients who underwent urgent appendectomy at Duke between January 1998 and September 2007.

The percentage of patients who had preoperative CT increased considerably over the 10-year period, from 18.5% in 1998 to 93.2% in 2007. The increased use of CT imaging corresponded with a lower negative appendectomy rate for women age 45 years or younger. The negative appendectomy rate among those women dropped from 42.9% in 1998 to 7.1% in 2007. The shift from single-detector CT to multidetector CT and other advances in CT technology also correlated with a reduction in false-positive diagnoses. "CT is a very helpful test for women 45 years and younger based on the overall trends we observed during the 10-year period,” Dr. Coursey said.

Increased use of preoperative CT at Duke University did not coincide with a lower negative appendectomy rate in men, regardless of age, or in women older than 45 years. Dr. Coursey suggested that the lack of a decline might be attributable to a very low negative appendectomy rate in those groups at the beginning of the study period.

"Although it's a terrific test, CT and our interpretation of CT images are not 100% perfect,” Dr. Coursey concluded. "Therefore, it may be difficult to improve significantly upon diagnosis in groups with an already low negative appendectomy rate.”

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