What is an anal abscess?

An anal abscess is an infected cavity filled with pus that develops near the anus or the buttock. The pus builds up under pressure beneath the skin causing pain and swelling.

What is an anal fistula?


An anal fistula usually develops as the result of an anal abscess. A fistula is a medical term describing a tunnel or an abnormal tract that forms under the skin and connects a previous abscess infection between the skin on the buttocks outside the anus to the anal canal inside.

What causes an anal abscess and an anal fistula?

Inside the anal canal are small anal glands. These glands may get infected when bacteria enters or when the glands get clogged. Certain conditions such as colitis or inflammation of the bowel can sometimes make these infections more likely. The pus may build up under pressure beneath the skin developing an abscess. The pressure may be relieved with the discharge of pus out of the external skin. However, after the pus in the abscess has been drained, the tunnel or tract may persist connecting the anal gland from which the abscess arose to the outside skin. When this occurs, persistent discharge from the outside skin opening indicates the persistence of this tunnel, now termed a fistula. This fistula tunnel can get infected repeatedly with repeated discharge of pus. Once developed an anal fistula rarely heals on its own.

What are the symptoms of an anal abscess or fistula?

An abscess often causes symptoms of pain and swelling around the anus. Fever, chills and fatigue may be present. Anal fistula may also cause skin discomfort and irritation around the anus as well as discharge of pus (which often relieves the pain temporarily). It commonly affects active adults in the 30 to 50 years old age group.

How is an anal abscess or fistula treated?

Types-of-Anal-Fistulas-FigureBThe best treatment for anal abscess is surgical drainage. Antibiotics are not really a good alternative to draining the pus, because antibiotics do not fully penetrate and treat the fluid within an abscess. Surgical drainage is performed under anaesthesia by making an opening in the skin of the anal abscess to drain the pus from the infected area and therefore also relieve the pressure.
Surgery is necessary to treat and cure an anal fistula. Fistula surgery is usually relatively straightforward. It often involves opening up the fistula tunnel or tract, this will require cutting a small portion of the anal sphincter muscle.

The internal and external openings of the tunnel are then converted into a groove to allow it to heal from inside out. Most fistula surgery can be done at the same time as the abscess surgery, as a day-case procedure. Very rarely the anal fistula is deep, or is complex with more than one tract. In these situations, specialised imaging tests will be required and alternative surgical techniques are needed.

What is the recovery period like after surgery?

The discomfort after anal abscess or fistula surgery is often mild and can be controlled with painkillers. The amount of time off work or school is usually minimal. The open wound at the anus would need to be cleaned regularly by using a warm water spray to the wound about 3 to 4 times a day. It is normal to have some blood-stained discharge from the open wound. It is recommended to wear a gauze pad or a hygiene pad to prevent the discharge from staining clothes. Stool softeners and mild laxative may be prescribed. Bowel movements will not affect the wound healing process.

What are the chances of recurrence of an abscess or fistula?

The wound may take up to 4 weeks to heal completely, although it is usually not uncomfortable after 2 weeks. If properly healed, the problem will usually not return. But if the wound fails to heal, it indicates recurrence; the chance of this is very low. It is important to follow the directions of the surgeon to help prevent recurrence.