Implementation of a structured CT reporting tool for the detection of internal hernia after Roux-en-Y gastric bypass

The radiographic diagnosis of internal hernia following Roux-en-Y gastric bypass (RYGB) can be difficult. Here, we sought to improve the detection of internal hernias through the implementation of a structured CT reporting tool.

This is a single-institution, retrospective cohort study of RYGB patients presenting to the Emergency Department. In 2023, an educational seminar and a structured CT tool were both implemented to incorporate the signs of internal hernia into CT reads. The tool incorporates the following: Antecolic/retrocolic Roux limb, jejunojejunostomy sidedness, abnormalities of the superior mesenteric vein, presence of mesenteric swirl or mesenteric edema, small bowel obstruction, small bowel clustering, bowel loops located posterior to the Roux limb mesentery, any significant changes in bowel loop configuration from prior CT scans, and a final impression of the presence or absence of internal hernia. A Pre-Intervention period of 1 year was used to compare CT scans 1 year after the implementation.

During the Pre-Intervention period, 139 CT scans were obtained. Five (3.0%) radiographic diagnoses of internal hernia were made, four of which underwent operative reduction. Six internal hernias (3.7%) were missed by CT. All six required surgical reduction, with one experiencing entire small bowel necrosis resulting in resection and small bowel transplantation. During the Post-Intervention period, 49.7% of the 193 CT scans included the structured CT reporting tool. Eight (3.7%) radiographic diagnoses of internal hernia were made, six of which underwent operative reduction. Two diagnoses of internal hernia were missed on CT scan (1.1%). The sensitivity for internal hernia detection in the Pre- and Post-Intervention groups was 40.0 vs. 75.0% (p = 0.14), and the specificity was 99.2 vs. 98.9%, respectively (p = 0.79).

Implementing a structured tool for the detection of internal hernias with CT scans may improve the diagnosis rates of internal hernia among those who have undergone RYGB.