Optimizing the diagnostic strategy for accurate detection of internal herniation following Roux-en-Y gastric bypass: a diagnostic accuracy study

Background: Internal herniation is a serious complication after Roux-en-Y gastric bypass (RYGB). Diagnosis is challenging due to nonspecific clinical findings, heterogeneous computed tomography (CT)-based predictive models, and lack of consensus on the optimal diagnostic strategy. Although diagnostic laparoscopic surgery (DLS) is considered the reference standard, it frequently results in negative explorations. Objectives: To identify predictive clinical parameters and CT signs for internal herniation in post-RYGB patients presenting with abdominal pain, and to evaluate the clinical decision-making process leading to DLS. Setting: Emergency department of a high-volume nonacademic teaching hospital with a dedicated bariatric center in the Netherlands. Methods: This prospective diagnostic accuracy study included all adults presenting with acute abdominal pain more than 30 days post-RYGB between March 2023 and June 2024. Standardized clinical, laboratory, and CT assessments were performed. A bariatric surgeon assigned a clinical suspicion score (CSS) and a dedicated radiologist a radiological suspicion score (RSS). Patient management followed a predefined protocol. Predictors were analyzed using Least Absolute Shrinkage and Selection Operator regression. Results: In total, 125 patients were included. DLS was performed in 84 patients (67%), confirming internal herniation in 30 (36%). CSS was not associated with internal herniation, whereas a higher RSS was strongly associated with its presence (P < .001). Venous congestion, swirl sign, and mushroom sign were identified as independent predictors. Conclusion: Clinical assessment alone has limited reliability in guiding decision-making regarding DLS in post-RYGB patients with abdominal pain. Structured CT assessment by a dedicated abdominal radiologist is the most accurate diagnostic tool and should be performed in all such patients.