Adult sigmoidorectal intussusception as an unexpected cause of lower gastrointestinal bleeding

A 95-years-old woman presented with sudden-onset rectal bleeding. All other systems were reviewed and were negative. The patient had a past medical history of Alzheimer disease, congestive heart failure, arterial hypertension and diabetes mellitus type 2. Vital signs were normal. There were neither signs of peritoneal irritation nor intestinal obstruction. On digital rectal examination, a soft mass was palpated about 9 cm from the anal verge. Routine analytical tests were within normal limits. The abdominal CT showed a sigmoidorectal intussusception. It was performed a colonoscopy revealing a segment of sigmoid telescoping into the rectum about 15cm from the anal verge. On this invaginated segment, there was a large sessile polyp, which was biopsied. Rectal bleeding was self-limited without additional measures. The histological examination showed tubular adenoma with high-grade dysplasia. Intussusception in the adult is uncommon, representing less than 5% of all cases of intussusception. Most of the cases are due to malignant lesions, which are pulled forward during peristalsis, leading to invagination. The early diagnosis represents a diagnostic challenge due to the clinical features are nonspecific, including symptoms of intestinal obstruction and rectal bleeding.