Spontaneous transanal evisceration of the small bowel through perforation of the sigmoid colon: a case report and new surgical approach.

Introduction and importance: Transanal evisceration of the small intestine is a rare surgical emergency that requires immediate intervention. Since its initial description in 1827, only three cases of evisceration secondary to perforation of the sigmoid colon have been documented. This case report describes the fourth case worldwide. Presentation of case: An 85-year-old woman presented with transanal small bowel evisceration after straining during defecation. Examination revealed prolapsed, congested but viable small bowel loops through the anal canal, without uterine or rectal prolapse. Emergency laparotomy identified sigmoid perforation likely due to chronic diverticulitis. Initial surgery involved sigmoid segment resection and blind stapling, followed by ICU care. A second-look laparotomy required 290 cm small bowel resection, sigmoidectomy, colorectal anastomosis, and loop ileostomy. Recovery was prolonged due to age and short bowel syndrome. The patient was discharged to a nursing home 2 months postoperatively. Discussion: Transanal evisceration involves small bowel herniation via rectal or sigmoid perforation, commonly due to rectal prolapse and sudden increase in intra-abdominal pressure. Surgical management includes emergency laparotomy, bowel viability assessment, resection, and repair. Hartmann's procedure is preferred in contaminated fields. Mortality has decreased significantly with improved techniques. Definitive care should address underlying pathology to prevent recurrence. Conclusion: Immediate surgical intervention is the mainstay of treatment in transanal evisceration of the small bowel. The choice of surgical approach depends on intraoperative findings. A staged surgical approach including second or even third look surgeries may improve small bowel preservation and improve clinical outcome.