Postop CT Scans May Fail to Detect Bowel Obstruction

Diedtra Henderson

November 13, 2013

Pricey computed tomography (CT) scans may fail to accurately identify patients with serious complications among gynecologic surgery patients at high clinical probability for suffering postoperative complications.

Mariam M. AlHilli, MBBCh, from the Department of Obstetrics and Gynecology, Division of Gynecologic Surgery, and the Department of Health Sciences, Division of Biostatistics and Information, Mayo Clinic, Rochester, Minnesota, and coauthors report the findings of their retrospective cohort review online November 6 in Obstetrics & Gynecology.

Use of CT scans has exploded in recent years in the United States, increasing from 3 million scans conducted in 1980 to more than 62 million scans performed annually now, Dr. AlHilli and colleagues note. Although the scans can register greater than 90% sensitivity in investigating abdominal complications, the diagnostic accuracy comes at the price of heightened exposure to ionizing radiation, increased expense, and prolonged recovery.

Therefore, the researchers sought to characterize the value-add of CT compared with clinical criteria among patients already strongly suspected to have bowel injury. They enrolled 205 patients who had undergone gynecologic surgery between January 2, 2008, and December 30, 2010, at the Mayo Clinic and who had had CT scans of the abdomen and/or pelvis performed within 42 days of surgery for a suspected bowel complication.

Overall, 38 (18.5%) patients had a bowel-related complication, including 22 patients with bowel obstruction, 10 with bowel perforation, and 6 with anastomotic leak. These patients tended to be older (mean age, 61.3 years) compared with those who did not have a bowel-related complication (mean age, 55.3 years; P =.033). They were also more likely to have coronary artery disease (7.9% vs 1.2%; P = .045), have had a laparotomy (92.1% vs 66.5%; P = .002), and have unexpected drainage from a wound, drain, or stoma (8.4% vs 0.6%; P <.001).

CT results showed a likely bowel complication in 37 patients, accurately detecting a problem in 34 patients and providing false-positives in 3. The overall sensitivity and specificity for the test were 89.5% and 98.2%, respectively.

Interestingly, CT had the highest specificity in the group designated as low-risk based on clinical characteristics. Among those 57 patients, CT identified 3 patients with bowel problems that would have likely been missed by clinical characteristics alone. The sensitivity and specificity in this group were 100% and 98%, respectively.

The authors say their study may help nudge clinicians toward safer and more conservative approaches to caring for patients and add that the value of CT imaging could be "maximized" by applying it to gynecologic surgery patients at low clinical suspicion of bowel complications.

"In patients with a low clinical probability of a postoperative bowel-related complication (based on absence of unexpected drainage from a drain, wound, or stoma, age younger than 45 years, minimally invasive surgery, and absence of history of coronary artery disease), positive CT findings can accurately determine patients requiring surgical intervention," the authors conclude.

The authors have disclosed no relevant financial relationships.

Obstet Gynecol. Published online November 6, 2013. Abstract

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