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Anal/Rectal Abscess


An anal, or rectal, abscess occurs when a cavity in the anus becomes filled with pus. In addition to extreme pain, the abscess can cause fatigue, rectal discharge, and fever. In some cases, anal abscesses can result in painful anal fistulas. This occurs when the abscess fails to heal and breaks open on the surface of the skin. If an anal abscess doesn’t heal properly, it can cause a lot of pain and ultimately require surgery.

What Causes an Anal Abscess? Who Is at Risk?

A blocked anal gland, a sexually transmitted infection (STI), or an infected anal fissure can cause anal abscesses. Some other risk factors for anal abscesses include:

  • Crohn’s disease or ulcerative colitis, which are inflammatory bowel diseases that cause the body to attack healthy tissue
  • diabetes
  • a compromised immune system due to illnesses like HIV or AIDS
  • anal sex, which can increase the risk of anal abscesses in both men and women
  • use of the medication prednisone or other steroids
  • current or recent chemotherapy
  • constipation
  • diarrhea

Toddlers or children that have a history of anal fissures (tears in the anal sphincter) are also at a higher risk for developing anal abscesses later on. Such anal fissures might occur in children who have a history of constipation.

What Are the Symptoms of an Anal Abscess?

A throbbing and constant pain in the anal area is probably one of the most common and immediately noticeable symptoms of anal abscess. The pain is usually accompanied by swelling in the anal area and greater pain during bowel movements.

Other common signs of an anal abscess include:

  • constipation
  • rectal discharge or bleeding
  • swelling or tenderness of the skin surrounding the anus
  • fatigue

Some people may be able to feel a nodule or lump that’s red, swollen, and tender at the rim of the anus. Fever and chills can result from the infection. You may also have rectal bleeding or urinary symptoms such as difficulty urinating.

Anal abscesses may also occur deeper in the rectum, most often in those who have inflammatory bowel diseases. This can result in some pain or discomfort in the abdominal area.

In toddlers, however, there typically aren’t many symptoms other than signs of discomfort or pain, which may cause a child to become irritable. A lump or nodule may also be visible or felt around the anal area.

How Is an Anal Abscess Diagnosed?

Anal abscesses are most often diagnosed through a physical exam where your doctor checks the area for characteristic nodules. They’ll also check for pain, redness, and swelling in the anal area.

In some people, there may not be any visible signs of the abscess on the surface of the skin around their anus. Instead, your doctor will instead use an instrument called an anoscope to look inside the anal canal and lower rectum. In some cases, the abscess may be deeper than a physical exam can find, so your doctor may order an MRI or ultrasound to get a better look.

Further tests may be necessary to make sure Crohn’s disease isn’t a contributing factor. In these cases, a blood test, X-rays, and a colonoscopy may be required. During a colonoscopy, your doctor will use a lighted, flexible scope to examine your colon.

Treatment Options for an Anal Abscess

Anal abscesses rarely go away without treatment. The most common and simple treatment is for your doctor to drain the pus from the infected area. This can usually be done in the doctor’s office. Your doctor will use a drug to numb the immediate area. Any uncomfortable pressure should be relieved, allowing the tissue to begin to heal properly.

If anal abscesses are left untreated, they turn into painful anal fistulas that may require more extensive surgical treatment. According to the American Society of Colon and Rectal Surgeons (ASCRS), about 50 percent of people who have an anal abscess will eventually develop an anal fistula. A fistula is an abnormal opening in the skin near the anus. A fistula generally requires surgery to close it and fix the problem.

If there’s an extremely large anal abscess, surgery may be required. In some cases, a catheter may be used to make sure the abscess drains completely. Abscesses that have been drained are typically left open and don’t require any stitches. If you have diabetes or a compromised immune system, your doctor may ask you to stay in the hospital for a few days to watch for any infection.

Once your surgery is done, it’s recommended that you take warm (not hot) baths. Sitting in warm water will help reduce swelling and allow for any more drainage the abscess may need.

Your doctor may also prescribe antibiotics if you have a compromised immune system or if the infection has spread.

Ways to Prevent Anal Abscesses

There isn’t much known about how to prevent anal abscess, but there are some steps you can take. Protection against STIs and prompt treatment is important for any infection. Condom use, especially during anal sex, is key in preventing STIs that may cause anal abscesses. Good hygiene and cleanliness in the anal area is an important safeguard for both children and adults.

Anal abscesses can cause complications, but they’re treatable. Understand the risk factors and make sure to closely monitor and manage any health conditions that might put you at an increased risk. If you notice any anal problems, make sure to contact your doctor to get treatment and to prevent them from becoming worse.

Content licensed from:

Written by: Carmella Wint, Matthew Solan, and Brian Wu
Medically reviewed on: Oct 20, 2015: Steven Kim, MD

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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