eP315 - A Rare Case of Sigmoid Intussusception Presenting as External Prolapse

Purpose/Background: External rectal prolapse is characterized by a circumferential, full-thickness protrusion of the concentric rings of the rectum through the anus, with an incidence of 0.5%. Intussusception is an invagination of a proximal loop of bowel into the distal segment, with an incidence of 0.0003%. A neoplastic lead point causes 70% of adult intussusception. Although rectosigmoid prolapse in patients with colon cancer has been reported, it is rare in patients who do not have a mass acting as a lead point. Here, we report a case of a blind pouch adjacent to an anastomotic staple line causing sigmoid intussusception prolapsing externally via the rectum.Methods/Interventions: A 76-year-old male with history of sigmoidectomy with primary anastomosis presented to the emergency department with one month history of severe rectal pain and bleeding. The patient was a poor historian. The indication for sigmoidectomy at an outside hospital was not known. He had no recent endoscopic evaluation. On exam, he had what appeared to be an incarcerated rectal prolapse with concerns for ischemia.Results/Outcomes: The patient was urgently taken to the operating room for perineal proctectomy. However, exam under anesthesia showed no evidence of rectal prolapse. Instead, a segment of viable dilated colon was telescoping externally via the rectum and a patulous anus. This was reduced intraoperatively. He subsequently underwent laparoscopic converted to open laparotomy. There was no mass. Sigmoidectomy, partial proctectomy, and end colostomy creation were performed. Primary anastomosis was not performed due to the risk of anastomotic complications in the setting of proximal dilation. Post-operative course was uncomplicated. Pathology showed colon and rectum measuring 17 cm in length with an internal circumference ranging from 5 cm to 19 cm. Patchy mucosal ulceration and ischemic type injury with fibrinopurulent exudate was seen abutting a previous anastomotic site with embedded staples.Conclusion/

Discussion: This is the first reported case of sigmoid intussusception prolapsing through the rectum caused by a previous anastomosis. A chronically dilated blind pouch from a side-to-end colorectal anastomosis was the most likely lead point. A large retrospective case series found 19.9% of all intussusceptions to be colonic in location with 46.5% and 36.8% accounting for malignant and benign causes, respectively. Only two case reports have previously described non-malignant prolapse of sigmoid intussusception. One case found the culprit to be pelvic floor dysfunction and chronic constipation, while the other was deemed to be idiopathic. In both cases the patients underwent reduction with sigmoid resection and primary anastomosis.

The low incidence coupled with an atypical presentation can make the diagnosis and management challenging. There are key general surgical principles that should guide management. First, any prolapse with incarceration and possible ischemic changes requires emergent intervention. Second, the lead point, which is most commonly malignant, should be identified and resected to prevent recurrence. In this case, we found it critical to reduce the prolapse, delineate the cause of the intussusception, and offer definitive management with colorectal resection.External ProlapseIncarcerated external prolapse of the sigmoid intussusception with concerns for ischemia