Emergency department experience with nonoral contrast computed tomography in the evaluation of patients for appendicitis.

STUDY OBJECTIVES: The American College of Radiology lists oral contrast as an institution-specific option in the evaluation of right lower quadrant pain. Previous literature indicates that an accurate assessment for appendicitis can be made by CT using IV contrast alone, with significant time savings from withholding oral contrast. Before 2010, the protocol for CT use in the evaluation of possible appendicitis or undifferentiated abdominal pain routinely included oral contrast. The purpose of this study was to determine the incidence of repeat CT scans with oral contrast for the purpose of arriving at a final disposition in patients undergoing evaluation for abdominal pain. This analysis was also to determine if the general surgery service was willing and able to make accurate clinical determinations to operate without the use of oral contrast.

METHODS: Consecutive abdominal CTs for nontraumatic abdominal pain were evaluated retrospectively over a 7-month period from January through July 2010. CT scans performed for evaluation of trauma were eliminated, as were cases in patients with known previous appendectomy or in cases in which appendicitis was not a consideration. Follow-up was by chart review over the ensuing 30 days for complications or need for surgery, which was not detected after the initial CT scan. The study was conducted at a teaching hospital, level I trauma center with an annual ED census of 99,000 visits.

RESULTS: A total of 311 CT scans met the study criteria. No cases of appendicitis were missed. Two patients were operated on based upon inflammatory findings in the right lower quadrant, one with typhlitis, the second with possible inflammatory bowel disease versus typhlitis. In each case, the diagnosis was made by CT, but the surgery service chose to operate based on clinical findings. Sixteen (5.14%; 95% CI, 3.2%-8.2%) cases of acute appendicitis were accurately identified. A normal appendix was visualized in 125 (40.2 %; 95% CI, 34.9-45.7) patients. No patients (0%; 95% CI, 0%-1.2%) required a repeat CT scan with oral contrast as part of the workup. On 30-day follow-up by chart review, no (0%; 95% CI, 0%-1.2%) significant surgical problems were identified, and no cases of missed appendicitis were identified.

CONCLUSIONS: Abdominal CT scan without the use of oral contrast is accurate to allow for appropriate decision making by emergency physicians and general surgeons. In our series, no patients required repeat scanning. Further assessment by larger studies is appropriate.