Perianal Abscess: Symptoms, Diagnosis, Causes & Treatment

A perianal abscess, also called an anorectal or anal abscess, is a pus-filled cavity near the anus. It can cause symptoms such as pain that worsens during bowel movements or when sitting, a lump in the anal area, bleeding, and yellowish discharge.

Most cases of perianal abscess occur when the anal glands become blocked, allowing bacteria to grow. However, certain conditions like cancer or inflammatory bowel disease, particularly Crohn’s disease, can also contribute to its development.

If a perianal abscess is suspected, it is important to seek emergency care for evaluation. The main treatment is surgical drainage, which should be performed by a colorectal surgeon.

Main symptoms

Common symptoms of a perianal abscess include:

• Pain in or around the anus, especially when passing stool or sitting

• Lump in the anal area

• Redness, swelling, or warmth in the affected region

• Increased sensitivity at the site

• Fever

• Bleeding or pus drainage

Pain from a perianal abscess is usually constant and located around the anus. It may worsen when sitting or during bowel movements. In some cases, the symptoms can resemble those of proctitis.

If the abscess ruptures, it may release pus and sometimes blood. Symptoms often improve gradually after this occurs.

How a diagnosis is confirmed

A perianal abscess is typically diagnosed by a colorectal surgeon or gastroenterologist, based on symptoms and physical findings during a rectal exam. In some cases, an anoscopy may be used.

Imaging tests such as ultrasound or MRI may also be recommended to examine the area in more detail and confirm the diagnosis.

Possible causes

In most cases, a perianal abscess develops due to a bacterial infection caused by blockage of the mucus-producing glands in the anal region.

Certain conditions can increase the risk of an anorectal abscess, including:

• Inflammatory bowel diseases, such as Crohn’s disease

• Infections affecting the rectum

• Injuries in the anal area

• Weakened immune system

• Side effects of radiation therapy

• Anorectal cancer

These conditions can lead to inflammation in the anal and rectal tissues, creating an environment where bacteria accumulate, pus forms, and pain during bowel movements may occur.

Treatment options

Treatment for a perianal abscess may involve:

1. Surgical drainage

The primary treatment for a perianal abscess is drainage of the pus. This should be done as soon as possible to lower the risk of a more serious infection. In most cases, it is performed under local anesthesia by a doctor and does not require hospitalization.

In more complex cases, hospitalization may be necessary so drainage can be performed in an operating room by a general surgeon or colorectal surgeon.

After drainage, rest, pain relievers, and warm sitz baths may be recommended to help reduce inflammation. Follow-up with a doctor is important to ensure complete healing of the abscess.

2. Antibiotics

Antibiotics should only be used if prescribed by a doctor. They are generally recommended in addition to drainage when the perianal abscess is large, involves significant redness, or when there is an increased risk of widespread infection, such as in people with diabetes or weakened immunity.

3. Treatment of associated conditions

In some cases, a fistula may develop in connection with a perianal abscess. A fistula is a channel that can form after pus drains or as a result of another condition, and it may interfere with recovery.

Treatment must then also address the fistula, which may be managed with surgery or by placing a material inside the fistula to encourage closure.

What to do if a perianal abscess does not improve

If a perianal abscess does not improve, medical evaluation is needed. After drainage, poor healing may result in the formation of a fistula, which can cause symptoms such as perianal swelling and discharge to persist or return.

In some cases, the abscess may come back, which is more likely within the first year after the initial treatment.

Possible complications

A perianal abscess may lead to complications such as an anal fistula, which can extend from the anus to the vagina, uterus, urinary tract, or other parts of the intestine.

Other complications include damage to the anal sphincter, which may cause fecal incontinence, or a necrotizing infection, where bacteria spread to nearby tissues like skin, muscles, and fat.

If treatment is not carried out properly, bacteria can spread into the bloodstream and cause a generalized infection, which can be life-threatening.