Case Report: Lesser omental hernia of the transverse colon associated with persistent descending mesocolon: a rare cause of acute large bowel obstruction

Introduction Internal hernia through a defect of the lesser omentum is a rare cause of intestinal obstruction, and herniation of the transverse colon in this setting is extremely uncommon. Persistent descending mesocolon (PDM) is a congenital anomaly of colonic fixation that increases intestinal mobility; its coexistence with transverse colon lesser omental hernia has rarely been documented. Case presentation A 48-year-old woman presented with a 12-hour history of acute epigastric colicky pain and vomiting. Examination revealed mild abdominal distension, epigastric tenderness and hyperactive bowel sounds, and laboratory tests showed leukocytosis with neutrophilia. Abdominal computed tomography (CT) demonstrated herniation of the transverse colon into the lesser sac. Because of the marked abdominal distension, a laparoscopic approach was considered hazardous (risk of iatrogenic bowel injury and incomplete exploration), and emergency laparotomy was therefore performed. Approximately 30 cm of the transverse colon was found incarcerated through a congenital defect of the hepatogastric ligament, accompanied by absent fixation of the splenic flexure. The incarcerated bowel regained color, mesenteric pulsation and peristalsis after reduction, confirming viability and eliminating the need for resection; the defect was closed with continuous non-absorbable sutures. The postoperative course was uneventful, and the patient was discharged on postoperative day (POD) 7 with no recurrence at 36 months of follow-up. Conclusion Lesser omental hernias involving the transverse colon are very rare, with PDM and loss of splenic flexure fixation predisposing to excessive colonic mobility. CT, especially contrast-enhanced CT, is the mainstay of preoperative diagnosis, and urgent operative intervention, with closure of the hernial defect, is indicated when there is clinical suspicion of an incarcerated or strangulated internal hernia; in particular, when abdominal pain is persistent and unrelieved and conservative management is judged unlikely to be effective, timely surgical intervention should be undertaken to prevent irreversible bowel ischemia and recurrence.