Can endometriosis cause cyclic rectal bleeding, and what tests help?

Yes—endometriosis can cause rectal bleeding that predictably flares with your cycle, especially when disease involves (or irritates) the rectum/sigmoid colon or nearby pelvic peritoneum. That said, rectal bleeding is never something we “assume is endo” without a careful workup, because other GI conditions can look similar and may coexist.

The most helpful starting point is a detailed symptom timeline (bleeding pattern relative to your period, pain with bowel movements, constipation/diarrhea swings, bloating, and any anemia symptoms) plus a focused pelvic exam. Imaging can help map suspected deep disease—most commonly an expertly interpreted pelvic MRI and/or targeted transvaginal ultrasound designed to look for deep endometriosis and related findings—but normal imaging does not reliably rule endometriosis out.

Depending on your symptoms and risk factors, we may also coordinate GI evaluation to look for other causes of bleeding (for example, hemorrhoids, fissures, inflammatory bowel disease, polyps), since those require different treatment. When endometriosis remains strongly suspected, the only way to confirm it is minimally invasive surgery with biopsy, ideally done in a setting where therapeutic excision can be performed at the same time. If you reach out, our team can help you choose the right sequence of testing so you get answers without unnecessary delays.