Rectal Contrast CT Scans of Limited Utility in Diagnosing Colonic Injuries in Penetrating Trauma: A Meta-Analysis

Using rectal contrast computed tomography (CT) to identify traumatic colorectal injuries has become commonplace; however, these injuries remain relatively infrequent findings on CTs obtained for penetrating back and flank trauma. We conducted a meta-analysis to ascertain the efficacy of rectal contrast CT in identifying such injuries in victims penetrating injuries.

PubMed and Embase were queried for relevant articles between 1974 and 2022. Review articles, case studies, and non-English manuscripts were excluded. Studies without descriptive CT and operative findings were excluded. Positive scans refer to rectal contrast extravasation. Sensitivity and specificity of rectal contrast CT scans were calculated with aggregated CT findings that were cross-referenced with laparotomy findings.

Only 8 manuscripts representing 506 patients quantified colorectal injuries and specified patients with rectal contrast extravasation. Seven patients with true colorectal injuries had no contrast extravasation on CT. There was one true positive scan. Another scan identified contrast extravasation, but laparotomy revealed no colorectal injury. Rectal contrast had sensitivity of 12.5%, specificity 99.8%, positive predictive value (PPV) 50%, negative predictive value (NPV) 99%, and a false negative rate of 88% in identifying colonic injuries.

The summation of 8 manuscripts suggest that the addition of rectal contrast in identifying colonic and rectal injuries may be of limited utility given its poor sensitivity and may be unnecessary. In its absence, subtle clues such as hematomas, extraluminal air, IV-dye extravasation, and trajectory may be additional indicators of injury. Further investigations are required to demonstrate a true benefit for the addition of rectal contrast.