Anal fistula

Anal fistula is the formation of a small infected tunnel connecting the skin near the anus and the end of the bowel. It is very painful and can lead to bleeding and discharge during defecation. In some cases, the drainage can be persistent, while in other cases it is recurrent.

Symptoms of Anal Fistula

Anal fistula causes unpleasant symptoms such as:

  • fever, around 380 C (100.4F) or above
  • constipation or pain during bowel movements
  • irritation, redness or swelling of the skin surrounding the anus
  • discharge of pus or blood during defecation
  • a constant and severe pain which worsens during bowel movements or while sitting
  • bad odor near the anus
  • trouble in controlling the bowel movements or bowel incontinence in some cases
  • fatigue
  • abdominal pain, loss of appetite, nausea, vomiting (if the anal fistula is caused by the inflammation of the intestines)

If your symptoms are persistent, then you must consult a doctor.


The leading cause of anal fistulas is a poor healing of the anal abscess. Nearly 25-50% of the patients with anal abscess develop an anal fistula. It can also occur as a complication with the surgical repair of anal problems.

Risk factors

The risk factors include:

  • Crohn's disease, which is the inflammation of the digestive tract
  • Diverticulitis, which is the infection of the small sacks on the sides of the large intestine
  • Tuberculosis and HIV infections


The risk factors include:

Infections: Like any other surgical procedure, surgery for anal fistula increases the risk of infections. If the fistula is not completely removed (i.e. if the surgery is carried out in several stages), then the infection can spread to the other organs.

Antibiotics are given either orally or intravenously based on the severity of the infection.

Incontinence: During the surgical repair, there can be damage to the sphincter muscles which can lead to bowel incontinence (uncontrolled bowel movement).

Recurrence: In some patients, the fistula can reoccur even after surgery.

Diagnosis involves the examination of the complete fistula for proper treatment. The opening of the channel is easy to detect and appears red, swollen and discharges pus and blood. But the examination of the internal opening is difficult and requires any of the below tests for visualization.

Test type Purpose of the test
Endoscopic ultrasound This gives a clear image of the sphincter muscles and other structures of the pelvic floor with the help of high-frequency sound waves
Fistulography This gives the X-ray of the fistula by using a contrast solution
MRI This technique is used when it is difficult to locate the fistulas

The other methods include the use of a fistula probe, anoscope, flexible sigmoidoscopy, etc.

Treatment for fistula depends on certain factors such as the location of the fistula, presence of sepsis or large abscess and the findings of the physical examination. The goal is to completely repair the fistula and prevent its recurrence and to safeguard the sphincter muscles. Damage of the sphincter muscles can lead to uncontrolled bowel movements.

Usually, surgery is the best treatment for anal fistulas. The main surgical procedures include:

Fistulotomy: This procedure involves cutting open of the fistula which heals into a flat scar. During 17th century, where the state of medicine was very bad, Louis XIV, the Sun King of France had anal fistula and was treated by fistulotomy.

Seton procedure: This procedure involves insertion of a small surgical thread called seton, in the fistula to drain the infection. This helps in healing before carrying another treatment.

Ligation of intersphincteric fistula tract: This procedure is done in two stages and is to treat complex fistulas. Initially, a seton is placed in the fistula to widen it. After several weeks, the infected tissue is removed, and the fistula opening is closed.

Other techniques such as filling the fistula with special medical glue or covering it with a tissue or blocking it with a special plug may be performed. For more complex fistulas, techniques such as ostomy and stoma, or muscle flap are performed.

Discuss the benefits and the risks of every procedure with your surgeon about the procedures before undergoing one.

Certain home remedies can help with your condition during the treatment. They are:

Fibrous diet: Foods rich in fiber content increase the stool volume and play an important role in the treatment of anal fistula. Examples include brown rice, brown bread, banana, barley, etc. Avoid spicy foods.

Drinking water: Drink plenty of water to soften the stools.