Anal fistula

Anal fistula

Anal fistula is the formation of an abnormal channel between the end of the large intestine and the skin in the anal or rectal area. This condition is caused by an infection that develops into a pus-filled lump (abscess) in the anal area.

Abscesses near the anus can continue to grow if not treated. Over time, the pus in the abscess will try to find its way out of the body and form a channel under the skin to the anus. This condition is called an anal fistula.


An anal fistula can cause pain and swelling around the anus, as well as a foul-smelling discharge of pus during bowel movements. This condition is more common in men and usually appears for the first time around the age of 40.

Causes of Anal Fistula

Most anal fistulas occur due to anal abscesses that are not treated or do not heal completely. Over time, the buildup of pus in the anal abscess will press on the area around it and seek a way out. As a result, a channel is formed from the abscess to the anus or rectum called an anal fistula.

Apart from being caused by an anal abscess, an anal fistula can also form due to the following conditions:

  • Crohn's disease
  • Injury to the anus
  • Diverticulitis
  • Tumor or cancer of the colon
  • Anal fissure
  • Sexually transmitted diseases, including lymphogranuloma venereum (LGV)
  • Bacterial infections, such as tuberculosis or  actinomycosis
  • Radiation therapy
  • Complications of surgery in the anal area

Risk factors for anal fistula

There are a number of factors that can increase a person's risk of experiencing an anal fistula, namely:

  • Male gender
  • Between 20–40 years old
  • Are overweight or obese
  • Have diabetes
  • Smoke
  • Suffering from high cholesterol
  • Rarely exercise or physical activity

Anal Fistula Symptoms

The following are a number of symptoms that can appear due to an anal fistula:

  • Pain in the anal area that gets worse when sitting, moving, having a bowel movement, or coughing
  • Irritation of the skin around the anus, such as swelling, skin discoloration to redness, and itching
  • Bleeding when defecating
  • Discharge of foul-smelling pus from the skin near the anus
  • Fever , chills, and fatigue

When to see a doctor

Immediately see a doctor if you experience the symptoms mentioned above, especially if you have had an anal fistula before, because this condition can come back. It is important to treat the condition as early as possible and prevent complications.

People with anal abscesses, sexually transmitted diseases, and Crohn's disease are more likely to develop anal fistulas. Therefore, if you experience the disease mentioned earlier, do routine checks to the doctor so that the condition is monitored and anal fistulas can be prevented.

Diagnosis of anal fistula

As a first step, the doctor will ask about the symptoms experienced by the patient and the patient's medical history. After that, the doctor will do a physical examination of the anus and the area around it.

The doctor will check for signs of irritation in the anus and the surrounding area, and see if there are small holes near the anal opening that ooze pus when pressed. The doctor will also perform a digital rectal examination to confirm the presence of an anal fistula.

Some fistulas can be detected only through physical examination, but others do not show signs on the skin surface and require further examination.

The following are some of the types of investigations needed to confirm the diagnosis of anal fistula:

  • Proctoscopy, which is an examination with a special instrument with a light on the end, to see conditions inside the anus
  • Fistula probe, which is an examination with special tools and dyes, to determine the location of the fistula tract and abscess
  • Anoscopy, which is an examination with a special instrument in the form of an anal speculum, to see conditions inside the anal canal
  • Colonoscopy , which is an examination with a camera tube inserted through the anus to see the condition of the large intestine and the cause of an anal fistula

Anal Fistula Treatment

Treatment of an anal fistula depends on its location and severity. The goal of treatment is to drain the pus and remove the fistula while protecting the anal muscles.

Anal fistula treatment will be done with surgery. Several types of surgery to treat anal fistulas are:

1. Fistulotomy

This surgical step is chosen if the location of the anal fistula is not or only slightly related to the sphincter muscle. Fistulotomy is done by opening the skin and muscles of the anal fistula tract, then cleaning the area and leaving it open so that natural healing occurs from within.

2. Blockage of the fistula

Blockage of the fistula is done after the pus is removed. In this procedure, the fistula tract will be blocked with a special material that can be absorbed by the body, eventually closing the fistula.

3. Installation of setons

In this procedure, thread-like material (ceton) is threaded through the fistula opening in the form of a knot. That way, the fistula canal can widen and pus from the abscess can come out.

The level of tension of the thread will be adjusted by the doctor so that the fistula can close during the recovery period. If the channel is closed, the thread will be removed. Generally, seton thread is installed for 6 weeks.

4. Tissue installation ( advancement flap procedure )

This procedure may be selected if the fistula passes through the sphincter muscle. In this procedure, the fistula tract will be dissected, cleaned, then patched with tissue taken from the rectum (the end of the large intestine), because of its sphincter-like nature.

5. Binding of the fistula tract or LIFT procedure

The LIFT procedure ( ligation of the intersphincteric fistula tract ) is also an option if the fistula is through the sphincter muscle. This procedure is performed by making an incision over the fistula, removing the inflamed central portion, then tying and sewing the edges to close the channel.

After surgery, doctors will generally prescribe pain relievers and antibiotics to treat pain and prevent postoperative infections. In addition, patients may also need to make periodic visits to the doctor to make sure anal fistulas are completely healed.

Postoperative care

To speed up the healing process, the doctor will advise the patient to take care of the postoperative wound independently. Recommended treatments include:

  • Soak your buttocks in warm water 3–4 times a day
  • Wearing pads in the anal area during the wound recovery period
  • Increase fiber-rich foods and drink water to prevent constipation
  • Taking laxatives to soften stool if needed

Patients can return to normal activities after being declared cured by a doctor.

Anal fistula complications

Some of the complications that may occur as a result of an anal fistula or its operation are:

  • Fecal incontinence
  • Recurrence of anal fistula
  • Anal stenosis (narrowing of the anus)

Prevention of anal fistulas

There are several ways you can do to reduce the risk of anal fistulas forming, namely:

  • Keeping the genitals, anus and the area around it clean
  • Do not change partners in intercourse
  • Do not smoke
  • Implement a healthy and balanced diet, and drink adequate amounts of water
  • Undergo treatment and regular check-ups with a doctor if you have a disease that can increase the risk of anal fistula
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