Diagnostic Performance of Individual CT Signs for Identifying Ischemia and Necrosis in Small Bowel Obstruction: A...

BACKGROUND. CT has established strong performance in diagnosing small bowel obstruction (SBO). Uncertainty remains regarding the performance of individual CT signs in diagnosing associated ischemia or necrosis. OBJECTIVE. The purpose of this study was to conduct a systematic review and meta-analysis of the diagnostic performance of individual CT signs for detecting ischemia and necrosis in patients with SBO. EVIDENCE ACQUISITION. The MEDLINE, Embase, and Web of Science databases were searched through April 2024 for original research studies evaluating the diagnostic performance of individual CT signs in detecting surgically confirmed bowel ischemia and/or pathologically confirmed bowel necrosis in patients with SBO; uneventful clinical follow-up was permitted for determining absence of these outcomes. Bivariate random-effects meta-analyses were performed for CT signs reported in at least three studies with at least 100 total patients. Signs were considered predictive of an outcome if exhibiting a pooled specificity exceeding 85% and a diagnostic OR (DOR) exceeding 10. Signs were considered to reliably exclude an outcome if they had a negative likelihood ratio (NLR) less than 0.10. EVIDENCE SYNTHESIS. The analysis included 19 studies reporting 2453 patients with 2489 SBO episodes (600/2029 [30%] with ischemia, 241/651 [37%] with necrosis). Of 14 signs evaluated for ischemia, four were predictive: increased unenhanced bowel wall attenuation (specificity, 98%; DOR, 30.50; sensitivity, 36%), reduced bowel wall enhancement (specificity, 92%; DOR, 15.80; sensitivity, 55%), diffuse mesenteric haziness (specificity, 89%; DOR, 22.30; sensitivity, 72%), and closed-loop configuration (specificity, 85%; DOR, 19.60; sensitivity, 75%). Of 11 signs evaluated for necrosis, one was predictive: increased unenhanced bowel wall attenuation (specificity, 92%; DOR, 18.00; sensitivity, 55%). No sign had a sufficiently low NLR to reliably exclude either outcome (lowest NLR was 0.30 for closed-loop configuration for both outcomes). CONCLUSION. In patients with SBO, four CT signs (increased unenhanced bowel wall attenuation, reduced bowel wall enhancement, diffuse mesenteric haziness, and closedloop configuration) were predictive of ischemia; one of these signs, increased unenhanced bowel wall attenuation, was also predictive of necrosis. No sign could reliably exclude either outcome. CLINICAL IMPACT. The identified signs could be prioritized when interpreting CT examinations in patients with SBO to help guide surgical decision-making. Additionally, non-contrast acquisitions may warrant inclusion in routine CT protocols for SBO evaluation.