Also known as: anal abscess, rectal abscess, perirectal abscess, perianal abscess, anal gland abscess.

An anorectal abscess is a collection of pus in the area of the anus and rectum.

Causes, incidence, and risk factors

Common causes of anorectal abscess include:

• Blocked glands in the anal area
• Infection of an anal fissure
• Sexually transmitted infection

Deep rectal abscesses may be caused by intestinal disorders such as Crohn’s disease or diverticulitis.

The following factors increase your risk for an anorectal abscess:

• Anal sex
• Chemotherapy drugs used to treat cancer
• Diabetes
• Inflammatory bowel disease (Crohn’s disease and ulcerative colitis)
• Use of medications such as prednisone
• Weakened immune system (such as from HIV/AIDS)

The condition may occur in infants and toddlers who are still in diapers and who have a history of anal fissures.

Symptoms

Swelling around the anus and a constant, throbbing pain are the most common symptoms. Pain with bowel movements may be severe.

Other symptoms may include:

• Constipation
• Discharge of pus from the rectum
• Fatigue and general malaise
• Fever, night sweats, and chills
• Lump or nodule, swolling, redness, tenderness at edge of anus
• Painful, hardened tissue

In infants, the abscess often appears as a swollen, red, tender lump at the edge of the anus. The infant may be fussy and irritable from discomfort, but there are usually no other symptoms.

Signs and tests

A rectal examination may confirm that you have an anorectal abscess.

A proctosigmoidoscopy may be done to rule out other diseases.

Rarely, you may need a CT scan, MRI, or ultrasound to determine where the pus collection is located.

Treatment

The problem rarely goes away on its own. Antibiotics alone usually cannot treat the problem.

Treatment involves surgery to open and drain the abscess.

• Surgery is done using local numbing medicine, along with medicine to make you sleepy or spinal anesthesia.
• Surgery is most often an outpatient procedure. The surgeon will cut open the abscess and drain the pus. You will go home the same day.
• If the pus collection is deep, you may need to stay in the hospital until the abscess has completely drained.
• After surgery, you will need warm sitz baths (sitting in a tub of warm water). This may help relieve pain, reduce swelling, and make the abscess easier to drain.

Drained abscesses are usually left open and there are no stitches.

Your doctor may prescribe pain medication and antibiotics.

You may need stool softeners. Practice good hygiene and eat a soft or liquid diet until the abscess has healed.

Expectations (prognosis)

With prompt treatment, people with this condition usually do well. Infants and toddlers usually recover very quickly.

Complications tend to occur when treatment is delayed.

Complications

• Anal fistula
• Body-wide infection (sepsis)
• Continuing pain
• Problem keeps coming back (recurrence)
• Scars

Calling your health care provider

Call your health care provider if:

• You notice a rectal discharge, pain, or other symptoms of anorectal abscess
• You have fever, chills, or other new symptoms after being treated for this condition

Prevention

Prevention or prompt treatment of sexually transmitted diseases may prevent this cause of anorectal abscesses. Use condoms during intercourse, including anal sex, to prevent such infections.

Frequent diaper changes and proper cleaning during diaper changes will help prevent both anal fissures and perianal abscesses in infants and toddlers.

Source: NIH.gov