It is not required that you be completely pain free after a BM to get an IBS diagnosis.Just many IBSers have rectums that send pain signals when even partly filled and when they are empty that portion of the pain goes away.However, not all IBSers have rectal hypersensitivity, and some IBSers have other issues that can cause pain after a BM, or pain from other parts of the colon that do not depend on the rectum being full to cause pain.I have rectal hypersensitivity AND other issues. Only the part of the pain from the RH goes away after a BM. The all over every moment of every day colon tenderness didn't care if I have a BM or not. It was always there.