What could cause rectal bleeding but still have a normal colonoscopy and egd?

Bleeding might: Be inermittent, or you could be bleeding from small intestine. Or it could be coming from outside the rectum, like external hemorroids. Sometimes, bleeding could be intermittent, and not seen during the study.

Small bowel and anus: When a work up involves an EGD and colonoscopy, it misses the small intestines - a capsule endoscopy or bleeding scan would be needed to assess bleeding sites in the small intestines. As well, a colonoscopy may miss the otherwise obvious hemorrhoids or anal fissures which could bleed from the anus.