LAUSR

An internal hernia (IH) is defined as the protrusion of abdominal viscera, commonly small bowel, through an orifice within the abdominal cavity. With an incidence of 0.9–1.75%, strangulation and obstruction secondary to IH is exceptionally rare. However, due to its non-specific signs and symptoms, diagnosis of IH is often delayed and therefore carries a significant mortality rate. In adults, anatomical abnormalities, previous surgery, redundancy of mesentery and states of increased intra-abdominal pressure are associated with the development of IH. In contrast, IH in the paediatric population commonly arise from congenital mesenteric defects in the small bowel mesentery. Herniation via the foramen of Winslow, an anatomical aperture between the lesser and greater sac, is exceedingly uncommon. We present the unusual case of a 10-year-old with an internal hernia via the foramen of Winslow, identified at laparotomy for abdominal trauma. An otherwise well 10-year-old male presented to the emergency department with severe generalized abdominal pain and vomiting after being kicked in the abdomen by a sibling. On review he was tachycardic but remained normotensive and afebrile. Abdominal examination revealed generalized peritonism and bedside eFAST scan was positive for free fluid in the left upper quadrant. Biochemistry showed a mildly elevated white cell count 12.8 10/L (NR 4.0– 11.0 10) and an elevated lactate 6.5 mmol/L (NR <2.0 mmol/L). Abdominal CT revealed a dilated small bowel loop in the central upper abdomen posterior to the stomach, likely in the lesser sac, with features of bowel wall thickening and loss of enhancement (Figs. 1 and 2). There was no pneumatosis intestinalis, venous gas or free gas noted. He underwent an urgent exploratory laparotomy which found a mid-jejunal closed loop obstruction secondary to herniation into the lesser sac via the foramen of Winslow. The herniated loop was reduced however the small bowel was non-viable. A small bowel resection was performed and a stapled end-to-end anastomosis was created. There were no other injuries found intraoperatively. Postoperatively he developed an ileus which required nasogastric decompression. Diet was slowly upgraded and he was discharged on day 8. At his 4 week follow up, he was progressing well. Accounting for just 0.1% of all abdominal hernias, internal herniation via the foramen of Winslow is exceptionally rare. Ordinarily, normal intraperitoneal pressures prevent herniation of contents through this foramen however an abnormally mobile mesentery, previous operations such as cholecystectomy and increased intraabdominal states have been suggested to increase the risk of herniation. Given temporal association of symptoms after trauma to the abdomen, we postulate that the acute change of intra-abdominal pressure secondary to abdominal trauma may have caused a loop of