Rectosigmoid Intussusception Presenting as Rectal Prolapse Secondary to Adenocarcinoma in a Young Postpartum Woman: A Report of a Rare Case.

Rectal prolapse and intussusception are rare in adults and particularly unusual in the postpartum period. We present the case of a 39-year-old woman, one month postpartum following cesarean delivery of twins, who developed rectal prolapse during pregnancy associated with persistent constipation. She later presented with rectal bleeding and mucus discharge. Computed tomography of the abdomen and pelvis demonstrated rectosigmoid intussusception, while colonoscopy revealed a large fungating and friable mass at 25 cm from the anal verge. Biopsies confirmed adenocarcinoma. Magnetic resonance imaging demonstrated a 7.5 cm sigmoid lesion confined to the bowel wall without extramural extension or suspicious lymph nodes. The patient underwent laparoscopic low anterior resection with stapled colorectal anastomosis. Pathology confirmed moderately differentiated adenocarcinoma invading the muscularis propria with clear resection margins and 17 negative lymph nodes (pT2N0, Stage I). Her recovery was uneventful, and she remains well on follow-up. This case highlights the importance of considering malignancy in young adults presenting with persistent rectal prolapse or intussusception, particularly in the postpartum setting, and demonstrates the role of timely imaging and colonoscopy in establishing the diagnosis.