Anorectal Abscess

What is an anorectal abscess?

An abscess is a pocket of pus from an infection. An anorectal abscess occurs in the area of the anus or rectum. The anus is the last part of your digestive tract. It’s at the end of your rectum. It has a ring of muscle (sphincter) that opens during a bowel movement to allow stool (feces) to pass through. There are many glands within the anus. If one of these glands gets clogged, it can get infected. An abscess may then form.

Cross section of anus showing abscess.

What causes an anorectal abscess?

An abscess in this area is usually caused by a clogged anal gland. It may be clogged with bacteria or stool.

Who is at risk for an anorectal abscess?

Anorectal abscess occurs more often in men than in women. It usually happens between ages 20 and 60, with the average age being 40.

A person is more at risk for anorectal abscess if they have any of the below:

Inflammatory bowel disease (IBD) such as Crohn’s disease
Certain medicines, such as chemotherapy for cancer
Objects placed in the rectum, such as during sex
Medicines that suppress the immune system after an organ transplant
Pregnancy
Diabetes
Anal fissure that doesn’t heal, from constipation
Sexually transmitted infections (STI)

What are the symptoms of an anorectal abscess?

Symptoms can occur a bit differently in each person. They can include:

Severe pain or discomfort near the anus. The pain is constant. But it may not happen with a bowel movement.
Tiredness
Fever
Night sweats
Constipation
Painful bowel movements
Swelling or redness near the anus
Lump or painful, hardened tissue near the anus
Pain in the lower belly (abdomen)
Fluid or pus leaking from the anus or buttocks

The symptoms of an anorectal abscess may look like other health conditions. See your healthcare provider for a diagnosis.

How is an anorectal abscess diagnosed?

Your healthcare provider will ask about your symptoms and health history. They will give you a physical exam. The physical exam will include your anal area. You may also have:

Digital rectal exam. The healthcare provider may gently put a gloved, lubricated finger into your anus. A tool called a speculum may also be used. It is inserted into the anus and gently expanded. This lets your provider see more of the anal area.
Proctosigmoidoscopy (sigmoidoscopy). A flexible tube with a light and a tiny camera is placed in the anus. This lets your healthcare provider look at the area.
Imaging test. You may also have an MRI, CT scan, or ultrasound (sonogram). One of these tests may be done to find the exact location of the abscess.

How is an anorectal abscess treated?

Treatment will depend on your symptoms, your age, and your general health. It will also depend on how severe the condition is. In some cases, you may need a full anorectal exam under anesthesia. This is to let your healthcare provider decide the best treatment. Treatment may include:

Draining the abscess. The healthcare provider will make an incision in the skin near the anus so the pus can drain. This eases the pressure and lets the tissues heal. This can be done in a healthcare provider's office. If you have a large or deep abscess, you may need to be in the hospital and possibly have surgery under general anesthesia. You may also need to be in the hospital if your immune system is weak and you get infections easily.
Local anesthesia. This can help ease pain.
Antibiotic medicine. In some cases, your healthcare provider may prescribe antibiotics. This medicine treats infection. But antibiotics alone are often not helpful. This is why drainage is very important.

Talk with your healthcare providers about the risks, benefits, and possible side effects of all treatments.

What are possible complications of an anorectal abscess?

Many people with an anorectal abscess develop an anal fistula. This is a small tunnel that opens up between the inside of the anus and the skin next to the anus. Pus from the abscess seeps out of this tunnel. A fistula often needs to be fixed with surgery.

Other possible complications include:

Pain
Infection
The abscess comes back

How can I prevent an anorectal abscess?

You can reduce your chances of having this condition by managing diabetes, STIs, and other risk factors. If you have IBD, you may need medicine to help prevent anorectal problems such as an abscess.

When should I call my healthcare provider?

Call your healthcare provider if you have pain, discomfort, or swelling in the anus or rectum.

Key points about anorectal abscesses

An abscess is a pocket of pus from an infection. There are many glands within the anus. If one of these glands gets clogged, it can get infected. An abscess may then form.
Symptoms can include pain and fever.
You are more at risk for an anorectal abscess if you are pregnant, or if you have diabetes or IBD.
You may have a digital rectal exam and a proctosigmoidoscopy.
The abscess may be drained in a healthcare provider's office or in the hospital.
Many people with an anorectal abscess develop an anal fistula. This is a small tunnel that opens up between the inside of the anus and the skin next to the anus. A fistula often needs to be repaired with surgery.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

Know the reason for your visit and what you want to happen.
Before your visit, write down questions you want answered.
Bring someone with you to help you ask questions and remember what your provider tells you.
At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.
Ask if your condition can be treated in other ways.
Know why a test or procedure is recommended and what the results could mean.
Know what to expect if you do not take the medicine or have the test or procedure.
If you have a follow-up appointment, write down the date, time, and purpose for that visit.
Know how you can contact your provider if you have questions.