An anal abscess is a collection of infected fluid, or pus, around the rectum or anus. With a prompt diagnosis and effective treatment, most anal abscesses will not cause long-term health consequences.

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Most anal abscesses respond to surgical drainage of the infected fluid. Untreated or advanced anal abscesses may lead to anal fistulas.

This article discusses the causes and diagnosis of anal abscesses, as well as the most effective treatments and prevention strategies.

The last section of the large intestine is the rectum. The stool passes through the rectum before it leaves the body through the anus.

The anal canal links the rectum to the anus, and this canal connects to the skin around the anus at the anal verge. Perianal skin surrounds the anal verge.

Anal abscesses occur in the anal verge region. When anal glands do not drain properly, they can become infected. This infected fluid then collects into an anal abscess.

Individuals who have an anal abscess may experience symptoms such as:

  • ongoing, throbbing pain
  • inflammation or swelling
  • redness or other discoloration around the anus
  • sensations of tenderness in the anal region
  • constipation
  • pus leaking from the abscess

The obstruction and subsequent infection of anal glands cause about 90% of anal abscesses. Individuals may also develop anal abscesses due to trauma to the anal region.

Certain medical conditions can elevate the risk of anal abscesses. These include:

These abscesses occur twice as often in males as in females. They also become more common in middle age, with the average age of onset being 40 years.

Not all individuals with an increased risk of anal abscesses will go on to develop them. However, people who experience the symptoms of an anal abscess should discuss any concurrent health conditions with a healthcare professional.

Doctors may begin the diagnosis of an anal abscess with a digital rectal exam. During this exam, they will first visually examine the anal exterior. They will then insert a gloved finger into the rectum, using medical lubricant to minimize discomfort.

By digitally probing the rectum, a doctor can determine whether any anal abscesses are present. They may order imaging tests to get a closer look at the location of the abscess fluid.

CT scans are a common imaging technique for visualizing anal abscesses. A CT scan can identify areas to which pus from the abscess has spread. CT scans with contrast dye can help distinguish between different types of abscesses.

Another common imaging technique for diagnosing anal abscesses is an MRI scan. An MRI device uses large magnets to acquire images of soft tissues in the human body.

Ultrasound tests may also act as an alternative to provide images of anal abscesses.

A person with an anal abscess should speak with a doctor to learn more about the different diagnostic tests available.

In most cases, anal abscesses respond well to surgical drainage. During this procedure, a healthcare professional makes an incision in the perianal skin. Pus from an abscess drains through this incision.

Individuals with minor abscesses can undergo this procedure in an outpatient clinic with local anesthesia. More complicated abscesses may require hospitalization and treatment with antibiotics.

People with an increased risk of complications, such as individuals with diabetes or compromised immunity, may need further care in a hospital setting to ensure that they have responded well to treatment.

Home remedies

After surgery, people can take steps to maximize their recovery at home. Many people recovering from abscess surgery may benefit from a sitz bath after any bowel movement. This warm bath can help clean the affected area.

Avoiding constipation is another important step to minimize discomfort during recovery. People can promote healthy bowel function by:

Although anal abscess surgery is generally enough to treat an abscess, certain complications may occur after this procedure.

Research shows that 30–50% of people who receive treatment for anal abscesses develop an anal fistula. A fistula is an abnormal passage that forms between the anal canal and the exterior area around the anus. The warning signs of an anal fistula may include nausea, vomiting, and pain.

Doctors can identify the presence of an anal fistula through imaging techniques. Most anal fistulas heal following surgical treatment.

Preventing complications

Cleaning the abscess regularly after surgery can help reduce the risk of an anal fistula. Consistently dressing the area can also prevent postoperative complications.

Antibiotic treatment after surgery can prevent the occurrence of anal fistulas. In one study from 2019, people who received antibiotics after surgery for anal abscesses had a 36% lower chance of developing an anal fistula.

Possible ways to prevent anal fistulas include:

  • following a balanced diet that is low in added salt and sugar
  • exercising regularly
  • maintaining a moderate weight
  • avoiding smoking

Learn more about recovery from fistula surgery.

People who have Crohn’s disease or have developed anal abscesses may remain at high risk of anal fistulas due to other symptoms they experience.

A person will need medical and surgical treatment to treat perianal Crohn’s disease. A person can work with a doctor to create a suitable treatment plan.

Anal abscesses are collections of pus around the rectal or anal regions. Infection of the anal glands is one of the primary culprits.

Certain health conditions can increase the risk of developing an anal abscess. These include obesity, diabetes, and Crohn’s disease.

Surgical drainage is the standard treatment for this condition. However, individuals with anal abscesses should work with a medical team to determine the best treatment option for them. With the right treatment and follow-up care, people with anal abscesses can expect to make a full recovery.