An anorectal abscess is a collection of pus in the anal or rectal region. It may be caused by infection of an anal fissure, sexually transmitted infections, or blocked anal glands. Symptoms include painful, hardened tissue in the perianal area, discharge of pus from the rectum, a lump or nodule, tenderness at the edge of the anus, fever, constipation, or pain
associated with bowel movements. Treatment involves drainage of the abscess.
Infection of an anal fissure (cleft or slit), sexually transmitted infections, and blocked anal glands are common causes of anorectal abscesses. Abscesses may occur in an area that is easily accessible for drainage, or higher in the rectum. Deep rectal abscesses may be caused by intestinal disorders such as Crohn's disease or diverticulitis. High risk groups include diabetics, immunocompromised patients, people who engage in receptive anal sex, and patients with inflammatory bowel disease.
Superficial perianal abscesses are not uncommon in infants and toddlers who are still in diapers and have a history of anal fissures. The abscess often appears as a swollen, red, tender lump at the edge of the anus. The infant may be fussy from discomfort but there are generally no other associated systemic symptoms. Surgical drainage and antibiotics provide prompt relief in such cases.
The last phase of the digestive process is the collection of and passing from the body of solid wastes. These wastes (what's left of what we eat after the water and nutrients have been taken by our bodies) collect in the rectum and then are expelled through the anus. The inside of the anus is lined with glands and four to six crypts or pockets. Sometimes one of these pockets gets filled with stool. This can cause the gland to become infected and develop an abscess. Abscesses just under the skin can be swollen, red, tender, and very painful. Abscesses higher in the rectum often cause fewer symptoms but may produce fever and pain in the lower abdomen. A doctor can usually see an abscess if it is in the skin around the anus. When no external swelling or redness is seen, however, a doctor can make the diagnosis by examining the rectum with a gloved finger. A tender swelling in the rectum indicates an abscess.
A doctor will take the patient's medical history and do a physical examination. Diagnosis will be based on the symptoms and the presence of pain or tenderness, swelling, redness and possible drainage of pus from the area. The presence of a fever or an elevated white blood cell count as measured by a blood test can confirm the presence of an infection in the body.
Treatment involves prompt drainage of the abscess. Depending on the location of the abscess, the procedure may take place in an outpatient setting. If the abscess is very deep, surgery with appropriate anesthesia may be indicated. Antibiotics have limited value except for people who have a fever, diabetes, or an infection elsewhere in the body. Usually, treatment consists of cutting into the abscess and draining the pus after a local anesthetic has been given. Occasionally, a person is hospitalized and undergoes general anesthesia before a doctor cuts and drains an abscess. Even with proper treatment, in about two thirds of people, an abscess leads to the formation of an abnormal channel from the anus or rectum to the skin (anorectal fistula).