BACKGROUND There are limited data available on the ability of computed tomography (CT) to accurately diagnose abdominopelvic pathology in acutely ill inpatients suspected of having an acute abdominal process. The purpose of this study was to evaluate the diagnostic accuracy of abdominal/pelvic CT with varying use of contrast agents in hospitalized patients. METHODS A retrospective review of all hospital inpatients (3/1/07-5/31/07) who underwent urgent or emergent abdominal/pelvic CT with any combination of contrast, intravenous (IV), oral, rectal, or unenhanced for a suspected acute abdominal process was performed. Data collected included demographics, combination of contrast used, CT diagnosis, time from CT scan to subsequent intervention, intervention type, and actual diagnosis of the acute abdominal process. Accuracy of CT was compared between enhanced and unenhanced imaging using Fisher's exact test. RESULTS A total of 661 patients were identified. Use of IV contrast alone was found in 54.2% of CT scans and was correct in 92.5% of cases. IV and oral contrast was used in 22.2% of CT scans and was 94.6% correct. Unenhanced imaging was performed in 16.2% and was correct in 92.5%. Oral contrast alone was used in 7.0% and was 93.5% correct. There was no significant difference in the ability to correctly diagnose a suspected acute abdominal process when enhanced CT imaging was compared to unenhanced (p > 0.05). CONCLUSIONS CT contrast administration in critically ill hospitalized patients is not necessary to accurately diagnose an acute abdominal process. Eliminating the use of contrast may improve patient comfort, decrease patient risk, and minimize financial cost.