Bowel Transition Points: Multiplicity and Posterior Location at CT are Associated with Small-Bowel Volvulus

Abstract

To retrospectively evaluate the sensitivity and specificity of the number and location of bowel transition points at computed tomography (CT) in the diagnosis of small-bowel volvulus, with surgical findings as the reference standard. This HIPAA-compliant study had institutional review board approval; informed consent was waived. One hundred adult patients who had undergone preoperative CT and who had surgically proved non-abdominal wall hernia small-bowel obstruction (n=68) or small-bowel volvulus (n=32) were retrospectively identified. The patients included 61 women and 39 men with a mean age of 57 years (range, 18-96 years). One reader, blinded to the diagnoses, recorded the number of transition points at CT, the anteroposterior location of each transition point relative to the anterior edge of the spine, and the presence or absence of a whirl sign. Statistical analyses were performed with the Fisher exact test, unpaired t tests, and multiple logistic regression. The frequency of the finding of multiple transition points was significantly higher in patients with volvulus (19 [59%] of 32) than in patients without volvulus (11 [16%] of 68) (P<.001). Transition points associated with volvulus were less likely to be located more than 7 cm anterior to the spine (four [12%] of 32 patients) than were transition points not associated with volvulus (31 [46%] of 68 patients) (P<.005). The whirl sign was an additional significant independent predictor of volvulus (P<.05). When all three of these predictors were present, the specificity for small-bowel volvulus was 100%. The presence of multiple transition points with a posterior location at CT in an adult with small-bowel obstruction is significantly associated with volvulus.