Unusual Cause of Rectal Bleeding: Thinking Outside the Colon

Clinical Presentation We present two cases of young females presenting to outpatient gastroenterology clinic with cyclical rectal bleeding. Patient 1: A 33 year old female with history of endometriosis who presented with 5 months of rectal bleeding occurring within two days prior to start of her menses. Physical exam was unremarkable. Labs were notable for iron saturation 9% and ferritin 8. EGD with biopsies was normal. Colonoscopy showed an erythematous mass with a 3 cm stricture in the distal sigmoid. Biopsies were nondiagnostic. Abdominal CT showed an elongated cyst with septation extending from right adnexa concerning for endometrioma as well as a collection of cysts in pelvis that were abutting the sigmoid colon. She was referred to colorectal surgery and gynecology. Patient 2: A 29 year old healthy female who presented with two months of rectal bleeding at the start of her menses. Labs and physical exam were unremarkable. Flexible sigmoidoscopy revealed a 6 mm polyp in rectosigmoid colon with surrounding nodularity. Biopsy of the polyp showed endometriosis. She was referred to her gynecologist. Discussion Endometriosis is presence of endometrial tissue outside of the uterus and can occur in 3-10% of women. Bowel involvement can be seen in 5-10% of cases and most commonly in the sigmoid colon and rectum. Lesions can involve the serosa as implants or they can penetrate the muscular layers (deep infiltrating endometriosis). Symptoms can range from alterations in bowel habits or rectal bleeding to obstruction and perforation. The diagnosis can be challenging. Endoscopic appearance of mucosa is often unremarkable and biopsies non-diagnostic. Multiple imaging modalities have been used but are not disease specific. Laparoscopy, while invasive, is the gold standard for histological confirmation. The purpose of treatment is elimination of symptoms and includes both medical and surgical options. In uncomplicated cases, treatment depends on age and desire to conceive. Resection is done for symptoms of obstruction, ongoing bleeding or if malignancy cannot be excluded. Intestinal endometriosis should be considered in young women who present with cyclic gastrointestinal symptoms.Figure 1Figure 2