High prevalence of asymptomatic internal hernias after laparoscopic anterior resection in a retrospective analysis of postoperative computed tomography

Purpose: Internal hernia (IH) after laparoscopic left-sided colorectal resection (small bowel herniating underneath the neo-descending colon) can be a potentially devastating complication, resulting in acute small bowel obstruction or ischemia. IH has been described as a rare occurrence in a few retrospective case series; however, patients undergoing laparoscopic resection seem to be more prone to this complication. We assessed the prevalence of IH in a large cohort of patients who had undergone laparoscopic left-sided colorectal resection for colon or rectal cancer (CRC). Methods: A database of consecutive patients at a single institution from 2012 to 2017 was reviewed. Postoperative abdominal computed tomography (CT) scans performed for routine cancer follow-up between 3 and 36 months after surgery were assessed retrospectively. Results: During the study period, 276 patients had undergone anterior resection for CRC, with 206 (75%) having been performed laparoscopically. A total of 198 eligible patients were identified, and a follow-up CT scan was available in 105 (53%) of these patients (median time to CT 10 months, range 3–34). Only one of the 198 (0.5%) patients presented with an acute small bowel obstruction secondary to an IH during follow-up. However, the prevalence of asymptomatic IH was noted to be much higher in the postoperative CT scans occurring in 22 of 105 (21%) patients. Conclusion: Asymptomatic IH after laparoscopic left-sided colorectal resection is common. Given the potential risk of acute small bowel obstruction and ischemia, routine closure of the mesenteric defect should be considered.