Lessons Learned After Computed Tomography Misdiagnoses of Internal Herniation After Gastric Bypass

Introduction: The aim of this study was to formulate recommendations in diagnosing internal herniation (IH) after laparoscopic Roux-en-Y gastric bypass (LRYGB).Methods: All patients that underwent LRYGB between 2011 and 2017 were retrospectively included. Subsequently, all CT scans and reoperation reports between 2011 and 2018 were screened for IH. All cases with discrepancies between radiological and clinical diagnosis were investigated further.Results: Out of the 525 CT scans for IH, 49 (9.3%) were found to be discrepant. After blinded review by two readers, 30 (61.2%) of these were considered initially misdiagnosed. In the remaining 19 cases, 9 were false negative (FN), and 10 false positive (FP). Eleven cases were considered to be intermittent IH (7 FN and 4 FP). One FP had surgery much later due to persistent complaints, which did eventually prove IH. One CT diagnosis of intussusception (FN) was an IH. Two FPs were adhesions. One FN and three FPs remained unexplained even with knowledge of clinical diagnosis (4/525; 0.8%).Conclusion: Not all discrepancies can be avoided, but three recommendations can be made. First, experienced reading improves accuracy and second opinion can prevent unnecessary reoperations. Second, intermittent IH remains a pitfall and should be considered if there is delay between complaints, CT scan, and reoperation. Third, adhesions should also be considered, especially in patients with dilated bowel loops.