The relevance of transition zones on computed tomography in the management of small bowel obstruction.

BACKGROUND: Frequently, radiologists emphasize radiographic transition zones (RTZs) on computed tomography (CT), which are areas of abrupt change from dilated to collapsed bowel, as pathognomonic for small-bowel obstruction (SBO) diagnosis and location. The relevance of RTZs to patient management remains unknown. The purpose of this study was to determine the surgical predictive value and intraoperative accuracy of RTZ. METHODS: A retrospective review of 200 patients with SBO who underwent abdominal CT at a single institution from 2002 to 2007 was performed. Statistical analysis was conducted using an unpaired t test, a Chi-square test, and multivariate analysis. RESULTS: Of the 200 patients with SBO, 150 (75%) had an RTZ. Seventy-five (38%) patients required operative intervention; 58 (39%) patients had RTZ and 17 (34%) patients did not have RTZ (P=NS). The presence of RTZ was not associated with increased probability of operative versus nonoperative management (odds ratio=1.19; 95% confidence interval [0.61-2.32]). The mean time to operative intervention was 3.6 days. Immediate operative intervention (<24 h) was equivalent in patients with versus without RTZ (57% vs 53%; P=NS) as was intervention for failed nonoperative management (43% vs 47%; P=NS). For patients who required operative intervention, RTZ correlated with intraoperative site of obstruction in only 31 (63%) patients. CONCLUSION: The presence of RTZs does not increase the likelihood of operative intervention or identify patients who will fail nonoperative management. RTZ should, therefore, not be used as a major criterion influencing operative versus nonoperative management decisions in patients with SBO. For patients who required operative intervention, RTZ had a 63% correlation with intra-operative findings, which makes it a useful adjunct to pre-operative planning.