Using gloved fingers, a doctor can feel tender swelling in the rectum, even when no external swelling can be seen. Abscesses higher in the rectum may cause no rectal symptoms but may produce fever and pain in the lower abdomen. Treatment Antibiotics have limited value except in people who have a fever, diabetes, or an infection elsewhere in the body. Usually, treatment consists of injecting a local anesthetic, cutting into the abscess, and draining the pus. Occasionally, a person is hospitalized and given general anesthesia before a doctor cuts and drains an abscess.
Most fistulas begin in a deep gland in the wall of the anus or rectum.
Sometimes fistulas result from drainage of an anorectal abscess, but often the cause can't be identified. Fistulas are more common among people who have Crohn's disease or tuberculosis. They also occur in those with diverticulitis, cancer, or an anal or rectal injury. Fistulas that connect the rectum and vagina may result from x-ray therapy, cancer, Crohn's disease, or an injury to the mother during childbirth. A fistula may be painful, or it may discharge pus.