Pneumatosis and portal venous gas: do CT findings reassure?

Background: Small, single-institution studies have suggested risk factors for bowel ischemia/necrosis (I/N) in patients with computed tomography (CT) findings of pneumatosis (PN) and portal venous gas (PVG). Here, analysis has been expanded in a large, multicenter study. Materials & methods: Logistic regression models and receiver operating characteristic curves were used to construct a scoring system for I/N in cases of PN/PVG. Results: Of 265 patients with PN/PVG identified, 209 had adequate data. In unadjusted analyses the following variables were significantly associated with I/N: age, peritoneal signs, ascites, the presence of both PVG and PN, blood urea nitrogen (BUN), CO2, albumin, and a history of hypertension, myocardial infarction, or stroke. In contrast, the CT findings of mesenteric stranding, bowel-wall thickening, and type of PN were not associated with I/N. In adjusted analyses, three variables were significantly associated with I/N: age >60 y (odds ratio 2.51, 95% confidence interval: 1.26-4.97), peritoneal signs (10.58, 4.23-26.4), and BUN > 25 mg/dL (3.08, 1.54-6.17), whereas presence of both PN and PVG (versus only one) was associated with an increase (but not statistically significant increase) in odds (2.01, 0.94-4.36). Although several ad hoc models were used to maximize diagnostic ability, with maximal odds ratio 174, the areas of receiver operating characteristic curves were all below 0.80, revealing suboptimal accuracy to diagnose I/N. Conclusions: Older age, peritoneal signs, and high BUN are associated with I/N, suggesting an ability to predict which patients need operation. CT findings traditionally suggestive of ischemic PN/PVG, however, do not diagnose I/N accurately enough to reliably identify patients needing operation. (C) 2013 Elsevier Inc. All rights reserved.