But it's the cause of rectal bleeding only 1 to 2 percent of the time. prolonged diarrhea, straining and anal intercourse can all cause anal fissures. When rectal bleeding is painless and develops after heavy lifting, a long car. Although rectal bleeding is common, only about one-third of those affected seek treatment. obesity, or anal intercourse. An anal fissure, a split or tear in the lining of the anus, causes bleeding and burning pain after bowel movements. Proctitis affects the last 6 inches of the rectum and can cause the following: More serious symptoms may occur, such as pus and blood in discharge Gonorrhea (gonococcal proctitis): The primary cause appears to be anal intercourse.