Many glands are found within the body’s anus. If one of these glands becomes clogged, it can get infected, and an abscess can develop. An anorectal abscess is a collection of pus under the skin in the area of the anus and rectum.

Symptoms

These are possible signs of an anorectal abscess:

• Pain or discomfort near the anus or buttocks
• Fatigue
• Fever
• Night sweats
• Constipation or painful bowel movements
• Swelling or redness near the anus
• Lump or painful hardened tissue near the anus
• Pain in the lower abdomen
• Pus drainage near the anus or buttocks

What are the risk factors?

These conditions may increase your chance of developing an anorectal abscess:

• Pregnancy
• Diabetes
• Crohn’s disease, which is an inflammatory bowel condition
• Certain medicines, such as chemotherapy drugs for cancer treatment
• Drugs that suppress the immune system after an organ transplant
• Foreign objects placed in the rectum (usually during sex)
• Anal fissures, or cracks, related to constipation that continues for a long time
• Sexually transmitted disease (STD)

Diagnosis

In most cases, your healthcare provider can diagnose an anorectal abscess by looking externally at the anus and through a digital rectal exam. This test involves the healthcare provider inserting a gloved, lubricated finger into your anus. A speculum can be inserted to allow the whole anal area to be seen. In some instances, a healthcare provider will need to do a proctosigmoidoscopy. This is a test in which a flexible tube with a light and a camera is placed in the anus to see the area. In other instances, an MRI, CT scan, or ultrasound might be needed to find out where the location of the abscess.

Treatment

The healthcare provider will probably treat your anorectal abscess by making a hole in the skin near the anus so the pus can drain. This relieves the uncomfortable pressure and lets the tissues heal. Often the procedure can be done in a healthcare provider's office. If you have a large or deep abscess, you might need to be in the hospital, In addition, in some instances a full anorectal exam must be done under anesthesia in the operating room before deciding on the best course of treatment. Healthcare providers can more carefully watch your condition in the hospital as the abscess is drained. You may also need to be in the hospital if your immune system is weak and you are prone to infection. In these cases, you might be given local anesthesia to help ease pain. In some cases, your healthcare provider may prescribe antibiotics. 

Complications

About half of people with an anorectal abscess develop an anal fistula. This is an abnormal opening in the skin near the anus. Pus bursts from the abscess and seeps out. A fistula usually needs surgery to repair it. Pain, infections, and recurrence are other possible complications of anorectal abscess.

Prevention

You can reduce your chances of developing this condition by managing diabetes, STDs, and other risk factors. If you have inflammatory bowel disease, such as Crohn's, medicines are usually needed to help avoid anorectal problems like abscess. 

When to call the healthcare provider 

An anorectal abscess needs immediate medical attention before other complications happen. If you have any pain, discomfort, or swelling in the anus or rectum, see your healthcare provider to find out the cause.