Can endometriosis cause pencil-thin stools?

Yes—endometriosis can be associated with pencil-thin stools, most often when disease affects the rectum/sigmoid colon or when pelvic inflammation and scarring change how the bowel moves and empties. Bowel endometriosis commonly involves the rectum and sigmoid, and symptoms can include constipation/diarrhea shifts, painful bowel movements (often worse around your period), bloating, and sometimes rectal bleeding. That said, pencil-thin stool is not specific to endometriosis and can also show up with pelvic floor coordination problems, IBS-like bowel sensitivity, or inflammatory bowel disease—conditions that can overlap with endometriosis or mimic it.

Because a “thin stool” pattern can reflect narrowing, spasm, or altered motility, we look at the full picture: timing with your cycle, pain with bowel movements, bleeding, and any imaging findings. Our team’s evaluation focuses on distinguishing bowel endometriosis from common look-alikes and coexisting GI conditions, and when appropriate we use expertly interpreted ultrasound/MRI to map suspected disease—while recognizing that imaging cannot reliably exclude endometriosis. If this symptom is persistent or new for you, reach out to schedule a consultation so we can help you understand what’s driving it and what treatment options make sense, including excision when bowel involvement is suspected.