Strangulated Small Bowel Obstruction Involving the External Iliac Artery after Pelvic Lymph Node Dissection: A Case Report on Stepwise Intraoperative Decision-Making to Prevent Vascular Injury.

INTRODUCTION: Postoperative anatomical-space-related internal herniation/strangulation after pelvic lymph node dissection (PLND) is uncommon but may be associated with a risk of inadvertent injury to major vessels or urinary tract-related structures.

CASE PRESENTATION: A 77-year-old man with a history of robot-assisted radical cystectomy with ileal conduit diversion and PLND presented with severe abdominal pain. Contrast-enhanced CT revealed a closed-loop small bowel obstruction (SBO) with suspected strangulation adjacent to the right external iliac artery. Emergency laparotomy revealed extensive ischemic and necrotic changes of the small bowel in the right pelvis. Gentle reduction was first attempted but was unsuccessful. Because the constricting structure could not be adequately identified and was considered to potentially involve critical structures requiring preservation, premature direct release or forceful division was avoided. Because direct visualization of the dorsal pelvic structures was limited, CT images were re-reviewed intraoperatively to confirm that the urinary diversion-related structures were separate from the clearly nonviable target bowel. Initial intraloop bowel transection was then performed within the nonviable segment to reduce tension and improve visualization, allowing subsequent identification of the right external iliac artery as the constricting structure. Approximately 230 cm of small bowel was resected based on bowel viability, while more than 200 cm of small bowel was preserved. The artery was preserved and fixed to the pelvic wall. The postoperative course was uneventful.

CONCLUSIONS: This case highlights a postoperative anatomical-space-related internal herniation/strangulation after PLND. When strangulated SBO occurs adjacent to a major vessel or other critical structures, premature direct release of an inadequately identified constricting structure should be avoided. In selected cases in which gentle reduction is impossible, initial intraloop bowel transection may be considered as a limited bail-out option only after confirming that the clearly nonviable target bowel is anatomically separate from urinary diversion-related structures. This approach may reduce tension and improve visualization for subsequent identification of the constricting structure.