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Enteral Contrast in the Computed Tomography Diagnosis of Appendicitis: Comparative Effectiveness in a Prospective Surgical Cohort

Drake, Frederick Thurston MD, MPH*,‡; Alfonso, Rafael MD*,‡; Bhargava, Puneet MD; Cuevas, Carlos MD; Dighe, Manjiri K. MD; Florence, Michael G. MD§; Johnson, Morris G. MD**; Jurkovich, Gregory J. MD††; Steele, Scott R. MD‡‡; Symons, Rebecca Gaston MPH; Thirlby, Richard C. MD; Flum, David R. MD, MPH*,‡The Writing Group for SCOAP-CERTAIN

doi: 10.1097/SLA.0000000000000272
Original Articles

Objective: Our goal was to perform a comparative effectiveness study of intravenous (IV)-only versus IV + enteral contrast in computed tomographic (CT) scans performed for patients undergoing appendectomy across a diverse group of hospitals.

Background: Small randomized trials from tertiary centers suggest that enteral contrast does not improve diagnostic performance of CT for suspected appendicitis, but generalizability has not been demonstrated. Eliminating enteral contrast may improve efficiency, patient comfort, and safety.

Methods: We analyzed data for adult patients who underwent nonelective appendectomy at 56 hospitals over a 2-year period. Data were obtained directly from patient charts by trained abstractors. Multivariate logistic regression was utilized to adjust for potential confounding. The main outcome measure was concordance between final radiology interpretation and final pathology report.

Results: A total of 9047 adults underwent appendectomy and 8089 (89.4%) underwent CT, 54.1% of these with IV contrast only and 28.5% with IV + enteral contrast. Pathology findings correlated with radiographic findings in 90.0% of patients who received IV + enteral contrast and 90.4% of patients scanned with IV contrast alone. Hospitals were categorized as rural or urban and by their teaching status. Regardless of hospital type, there was no difference in concordance between IV-only and IV + enteral contrast. After adjusting for age, sex, comorbid conditions, weight, hospital type, and perforation, odds ratio of concordance for IV + enteral contrast versus IV contrast alone was 0.95 (95% CI: 0.72–1.25).

Conclusions: Enteral contrast does not improve CT evaluation of appendicitis in patients undergoing appendectomy. These broadly generalizable results from a diverse group of hospitals suggest that enteral contrast can be eliminated in CT scans for suspected appendicitis.

A total of 8089 patients underwent computed tomographic (CT) scan before appendectomy. Regardless of hospital type (urban or rural, teaching or nonteaching), agreement between final radiology report and final pathology report was the same for patients scanned only with intravenous contrast and those scanned with both intravenous and enteral contrast. Enteral contrast can be eliminated in CT scans for suspected appendicitis.

*Departments of Surgery

Radiology—University of Washington Medical Center

University of Washington Surgical Outcomes Research Center (SORCE)

§Swedish Medical Center

Virginia Mason Medical Center

Surgical Care and Outcomes Assessment Program (SCOAP) and Clinical Effectiveness Research Translation Network (CERTAIN), Seattle, WA

**Skagit Valley Hospital, Mount Vernon, WA

††Denver Health Medical Center, Denver, CO

‡‡Department of Surgery, Madigan Army Medical Center, Fort Lewis, WA.

Reprints: Frederick Thurston Drake, MD, MPH, Department of Surgery/University of Washington, 1959 NE Pacific Street, Box 356410, Seattle, WA 98195. E-mail: ftdrake@u.washington.edu.

Disclosure: SCOAP-CERTAIN research projects are supported by the Life Discovery Fund of Washington State and the Agency for Healthcare Research and Quality. The administrative home for SCOAP is the Foundation for Healthcare Quality. Dr Drake was supported by the National Institutes of Health in the form of a T32 training fellowship grant from the National Institute of Diabetes & Digestive & Kidney Diseases (grant 5T32DK070555-03). All authors report no potential conflicts of interest.

© 2014 by Lippincott Williams & Wilkins.