Anal Abscess and Fistula

Anal or perianal abscess is an infected pus-filled cavity near the anus or lower rectum. Anal fistula is a small tract or tunnel that orginates from inside the anal canal to a skin opening near the anus. Anal abscess often originates from small anal gland that gets infected. The abscess may or may not rupture on its own. Up to 40% of the abscesses may lead to fistula, but a fistula can form without an abscess.

Causes of perianal abscess and fistula

90% of abscess and fistula are caused by clogged anal glands that become infected (similar to pimple on skin due to clogged hair follicles). Anal glands are normal anatomy and unfortunately we do not know why they get infected most of the time and how to prevent them from occuring in the first place or from coming back. Occasionally, a deep anal fissure can lead to anal abscess and fistula. Other less common causes include Crohn's disease, anal or rectal cancer, trauma and radiation treatment to organs in the area.

Symptoms of perianal abscess and fistula

For anal abscess, pain and swelling in the anal area are most common symptoms. If the infection is severe, you may have more intense pain and redness in the area, along with fever or chills or ill-sensation. A superficial abscess can be felt just under the skin and may drain fluid or pus sponatneously when ruptured.

A fistula may have symptoms of anal abscess, often mild but recurring in same location every few weeks to every few months. A small opening may or may not be seen on the skin near the anus. When the opening is present, you may have small amount of yellow-to brownish fluid drainage on-and-off, with or without blood.

Diagnosis and treatment of perianal abscess and fistula

Most abscesses and fistulas can be diagnosed clinically with a thorough history and exam in the office by Dr. Choi. Occasionally imaging studies such as CT scan or MRI may be needed. Evaluation by a colorectal specialist is important for accurate diagnosis and to exclude uncommon or more severe conditions as the underlying cause, which may require further testing and different treatment. Treatment of abscesses typically require surgical incision and drainage to relieve the acute infection. This may be done as a simple office procedure under local anesthesia in Dr. Choi's office. Antibiotics alone may not be enough. Larger deeper abscesses may need to be drained in the operating room under general anesthesia.

Anal fistula treatment requires surgery, which is typically done as same-day outpatient surgery in the operating room under anesthesia. The surgical approach depends on the complexity of the fistula (how deep or how it travels through the anal sphincter muscle, if there are more than one fistula or the fistula branches). Multiple surgeries may be needed in complicated cases. Dr. Choi is experienced with different surgical techniques to treat anal fistula and will choose the approach most appropriate for your condition. The ultimate goal of the surgery is to eradicate the fistula, prevent it from coming back, and cause no harm to the anal sphincter function (anal sphincter is the muscle that you use to control when to have your bowel movement).

Helpful links:


*American Society of Colon and Rectal Surgeons