Rectal prolapse arises from benign etiology. When symptoms of internal intussusception mirror those of rectal prolapse, a misdiagnosis is possible, especially under limited clinical presentation. It is crucial to recognize and differentiate rectal prolapse from internal intussusception because the two diagnoses have different prognoses. Here, we describe a case of adult sigmoid intussusception presenting as rectal prolapse.

A 64-year-old woman with no known medical history visited a gastrointestinal outpatient department due to hard bloody stool defecation for 1 wk followed by constipation for 3 d. Colonoscopy revealed a huge polypoid ulcerated tumor at the sigmoid colon with lumen stenosis. The patient was admitted due to post-procedural dull abdominal pain. Due to failed colonoscopy reduction and stent insertion, the patient underwent sigmoid colon resection with primary end-to-end anastomosis, with the transverse colostomy pathological report showing adenocarcinoma, pT3N0M0. She recovered well from the operation and was discharged with regular outpatient clinic follow-up.

Presentation and manifestation of sigmoid intussusception may resemble that of rectal prolapse, necessitating careful observation due to distinct prognostic implications.