These are sores inside the rectum, beginning just past the anal canal. They arise most often from digging out hardened stool inside the back passage with a finger. Apart from that, inflammatory bowel disease, cytomegalovirus and herpes simplex virus infection, and radiation are causes of solitary rectal ulcer.
Sources
- Prof. Ali Tüzün İnce, MD — Kadıköy Endoscopy Center archive