Surgery-confirmed internal hernia with or without Roux-en-Y anastomosis: diagnostic performance of six CT signs.

PURPOSE

To assess the diagnostic performance and generalizability of established CT signs of internal hernias across a broad patient population including those with and without Roux-en Y anastomosis.

METHODS

Our institutional review board approved this retrospective study. CT scans of 21 patients (11 women, 10 men) with surgically confirmed internal hernia and 52 control patients (23 women, 29 men) in whom internal hernia was suspected on CT but subsequently excluded surgically were reviewed. Six CT signs were evaluated: non-duodenal small bowel (ND-SB) behind the superior mesenteric artery (SMA), right-sided jejunojejunal anastomosis in applicable patients, "swirl" sign, superior mesenteric vein compression, "mushroom" sign, and clustered small bowel (SB) loops. Sensitivity, specificity, and odds ratios with 95% confidence intervals were calculated for each sign using logistic regression.

RESULTS

Logistic regression identified the "mushroom" sign, clustered SB, and ND-SB behind the SMA as significant independent predictors of internal hernia with an area under the receiver operating characteristic curve of 0.746. The sensitivity, specificity, and odds ratio of the "mushroom" sign, clustered SB, and ND-SB behind the SMA were 38.1%, 86.5%, 3.96 (95% CI, 1.21-12.97), 47.6%, 75.0%, 2.73 (95% CI, 0.94-7.89), and 33.3%, 88.2%, 3.75 (95% CI, 1.08-13.02), respectively.

CONCLUSION

The "mushroom" sign, clustered SB, and ND-SB behind the SMA are valuable CT findings in diagnosing internal hernias irrespective of Roux-en-Y anastomosis. In particular, ND-SB behind the SMA and the "mushroom" sign are highly specific.