Complication of Internal Herniation-related Bowel Obstruction Post-Single Anastomosis Sleeve Ileal (SASI) Bypass and Management: Series Case Sharing (Video Report)

Background: Obesity is a global health concern associated with multiple comorbidities, and bariatric surgery remains one of the most effective interventions for sustained weight loss and metabolic improvement. The Single Anastomosis Sleeve Ileal (SASI) bypass is a novel procedure that offers a simplified surgical approach while maintaining efficacy. However, despite its advantages, SASI bypass carries a risk of postoperative complications, including internal herniation-related bowel obstruction—a rare but potentially life-threatening condition requiring prompt recognition and intervention. Method: We report 3 cases of internal herniation following SASI bypass, 2 performed robotically and 1 laparoscopically. Despite uneventful surgical procedures, all 3 patients developed postoperative internal herniation, with symptom onset ranging from 1 week to 16 months after surgery. A comparative summary of their clinical presentations and outcomes is provided in the accompanying table. Due to timely diagnosis and prompt surgical intervention, all patients had favorable outcomes. In addition, we compiled and edited a surgical video from the third case to illustrate the operative management of this complication. Results: Computed tomography (CT) emerged as the gold standard for diagnosis, although immediate surgical exploration was necessary in cases of peritonitis or hemodynamic instability. Notably, 1 patient (Case 2) experienced rapid weight loss, a factor previously implicated as a potential risk for internal herniation. Petersen’s defect was the most common herniation site in SASI bypass, resembling the pattern seen in One Anastomosis Gastric Bypass (OAGB) but differing from Roux-en-Y Gastric Bypass (RYGB), where multiple mesenteric defects increase the risk. While a longer biliopancreatic limb may predispose SASI and OAGB patients to herniation, consensus on routine defect closure remains lacking. Conclusion: Internal herniation is a rare but serious complication of SASI bypass, with delayed diagnosis potentially leading to bowel ischemia or perforation. CT is essential for early detection, while timely surgical intervention is critical in symptomatic cases. The necessity of routine Petersen’s defect closure remains debated, highlighting the need for further studies to determine the true incidence and optimal prevention strategies.