Is unenhanced CT sufficient for evaluation of acute abdominal pain?

Background: To determine whether intravenous contrast improves the ability of radiologists to establish the cause of acute abdominal pain after nondiagnostic or normal unenhanced CT. Methods: Out of 164 consecutive emergency department patients presenting with less than 48 h of nontraumatic, acute abdominal pain, a confident diagnosis for cause of pain was made prospectively in 71/164 (43%) patients on these unenhanced scans by the monitoring radiologist. In the other 93 patients, our study sample, intravenous contrast-enhanced CT was obtained. At a later date, retrospectively, two experienced abdominal CT radiologists independently evaluated unenhanced CT scans alone for potential causes of pain and diagnostic confidence level on a 1–3 scale. At least 2 weeks later, intravenous enhanced and unenhanced scans were read side-by-side for the same assessment. Results: There was no significant difference in diagnostic confidence levels comparing unenhanced CT alone (2.59) vs. intravenous enhanced and unenhanced CT together (2.64). Chi-square analysis found no significant difference in finding a cause for pain when intravenous contrast was added compared to the initial unenhanced scan alone. Conclusions: Intravenous contrast did not significantly improve the ability of CT to establish a cause of abdominal pain after a negative or nondiagnostic unenhanced CT.