An anal, or rectal, abscess occurs when a cavity in the anus becomes filled with pus. It causes extreme pain, fatigue, rectal discharge, and fever. In some cases, anal abscesses can result in painful anal fistulas. This occurs when the abscess doesn’t heal and breaks open on the surface of the skin. If an anal abscess doesn’t heal, it can cause a lot of pain and may require surgery.
A blocked anal gland, a sexually transmitted infection (STI), or an infected anal fissure can cause anal abscesses. Some other risk factors include:
Crohn’s disease or ulcerative colitis, which are inflammatory bowel diseases that cause the body to attack healthy tissue
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
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.
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:
rectal discharge or bleeding
swelling or tenderness of the skin surrounding the anus
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, 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.
Anal abscesses are most often diagnosed through a physical exam where your doctor checks the area for characteristic nodules. You doctor will 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. You doctor will instead use an instrument called an endoscope to look inside the anal canal and lower rectum. Sometimes the abscess may be deeper than a physical exam can find. Then, you 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, imaging, and a colonoscopy may be required. During a colonoscopy, your doctor will use a lighted, flexible scope to examine your colon.
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 medicine to numb the area. Any uncomfortable pressure should be relieved, allowing the tissue to begin to heal properly.
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 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.
After surgery, it’s recommended you take warm (not hot) baths. Sitting in warm water will help reduce swelling and allow for more drainage the abscess.
Your doctor may also prescribe antibiotics if you have a compromised immune system or if the infection has spread.