Anal Fistula – Symptoms, Causes, Surgery, Treatment

When the area from which feces are thrown out from the body gets blocked it give rise to the formation of abscess (infected cavity) and such an abscess will form anal fistula. Anal fistulas are small abscess of infection inside the anus which may give rise to pain and swelling around the anus. Very often, the fistulas are formed from anal abscess but sometimes it can also occur due to sexually transmitted disease and infectious disorder like tuberculosis.

The symptoms of anal fistula are bleeding, anal abscess pain with swelling, foul smelling pus discharge and occasional fever with chills. Anal fistula can be diagnosed by physical examination of anus and also by testing procedure. If needed, your doctor will ask you to do MRI scan of the anus for clearly defining the fistula tract. In case of detection of fistula, further testing would be done for Crohn’s disease in the intestine. Generally fistulas are seen on people with Crohn syndrome.

Surgery is done for severe case of anal fistula, if it becomes unmanageable. Fistulotomy is the procedure of removing fistulas from the anus during which the muscular area are opened, thus converting the abscess into groove. This facilitates the healing process quickly. In complicated cases of anal fistula, a seton is replaced in the area which should be kept for minimum 6 weeks and can be removed thereafter. There may be pain and little discomfort after surgery and you can take pain killer medicines for complete healing and recovery.

What Is A Fistula?

Anal fistula is a small pus-filled cavity in and around the anus area. Very often it is caused by infection of the internal glands and sometimes it can be caused by bacteria. Anal fistula is also known as anal abscess. In rare cases fecal particles (hardened) can clog together to block the anal cavity forming abscess inside the anal canal or cavity.

More than half of the cases diagnosed with anal fistula would already have abscess. Anal fistula can also occur without an abscess and is found near the skin of the buttocks close to the opening through which stool is pushed out. Anal fistula occurs in the form of small channel between the skin of the anus and end of the opening. It can cause leakage of blood in the stools and can be painful. It can occur in the postoperative cases for which rectal surgery is performed. Anal fistula can be treated only by surgery.

Anal Fistula Types :

  • Anal fistulas are classified into many types based on its location with respect to the surrounding structures of the anus. Some of them include peri-anal, intersphicteric fistula and ischio-anal fistula. In most of the cases perianal fistulas are present.
  • Anal fistulas can also be categorized with respect to its place or occurrence connected to anal sphincter region like superficial fistula, trans-sphicteric fistula, extra sphincteric fistula and inter sphincteric fistula.

Anal Fistula Symptoms :

Presence of anal fistula can cause pain while passing stool, swelling around the area of rectum and scarring of skin surrounding the anus. For some people it can cause bloody leakage with stool and irritation and burning pain while urinating. Foul smelling discharge can occur from the anus due to infection. In severe cases fever and body pain may develop as additional symptom of abscess. Very often they occur in patients with preexisting complaints of anal abscess.

Causes Of Anal Fistula :

Several glands are preset inside the anus and when any one of them gets infected it may lead to collection of pus, called as abscess. People with weakened immunity are at risk of getting an abscess and they are often treated with antibiotics. In most of the cases anal abscess gets healed but the doctor will have to drain the pus from the abscess. In some cases, anal abscess get burst out before it is drained fully causing anal fistula.

Anal fistulas are formed if the underlying abscess has not healed fully and if the pus filled fluid has not been drained fully. About 30-50% of cases diagnosed with anal abscess would develop anal fistula for which the basic cause is anal infection. In rare cases fistulas are formed as a complication of inflamed intestine like that of diverticulitis or Crohn’s disease. Anal fistulas can develop due to severe bacterial infection like TB, immunocompromised infections like HIV or due to sexual infection like Chlamydia or syphilis.

Pictures of Anal Fistula :

Images, Pics, Pictures and Photos of Anal Fistula

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Diagnosis :

Based on the symptoms, the doctor may examine the anus region carefully with anoscopy to detect any perirectal abscess inside. He would gather complete medical history of the patient and ask questions about previous history of abscess. If necessary he may order for digital examination of the rectum with the help of CT/MRI scan or with ultrasound scan.

During physical exam, external opening can be detected with pus or blood indicating presence of anal fistula. However in some cases the fistula would close automatically not fully allowing the drainage making it difficult for the doctor to identify. On the basis of test results, your doctor may request for additional tests for screening sexual infection or inflammatory bowel disease. If necessary he may do a biopsy also.

Anal Fistula Treatment :

Surgery is the ideal method for draining the pus from the anal abscess. Normally the procedure can be done on outpatient basis in the doctor’s office. You will be given local anesthesia and the surgeon will make a small incision near the anus to drain off the pus inside. After the drainage of the pus a tunnel or fistula may be present inside. This fistula usually occurs as small tube connecting the anal gland (infected) and the superficial skin.

In case the opened skin heals even with the presence of fistula you are sure to get abscess again. The fistula has to be completely eliminated failing which anal abscess can recur many times causing pain and swelling.


There are no medications available till date to destroy fistula and hence surgery is the only choice left. Fistulotomy is the process of removing the fistula along with sphincter muscle. The surgeon will cut open the anal canal to detect the exact location of anal fistula. Fistulotomy is the most effective surgery for treating anal fistula and the success rate is high. However this surgery can cause some adverse effect on the patient like incontinence. Your doctor will discuss several aspects of the surgery along with surgeon.

Fibrin Glue Injection

In this procedure, anal sphincter muscle is not disturbed or divided. Certain type of fibrin glue is given directly as a shot into the fistula to destroy it completely. But this procedure may not be successful all the time and hence not preferred by many surgeons.

Fistula Plug

The length of the fistula is measured and a piece of material having the exact length is placed alongside the fistula so that it gets incorporated into it along with the tissue. However the success rate is only 50% in this procedure.

Complex Fistulas

For treating complex type of fistulas endoanal flap is administered. Here the internal hole of the fistula is fully covered with healthy tissue so that point of origin gets blocked. In this case also rate of recurrence is 50%. Most of the above procedures can be performed at the doctor’s office but some patients may be hospitalized for few days.

Seton Draining

Seton draining is the procedure of placing a thin rubber piece throughout the length of fistula from the place of its origin till the end thus forming a ring surrounding the anus and fistula tract. The seton will be kept intact for few weeks for preventing draining and allowing the inflammation to reduce.

Prognosis :

Anal fistula surgery is often successful with fistulotomy. The patient can get pain around the anus for few weeks which can be managed with painkillers and by using laxatives. It is advisable to use Sitz baths many times a day to prevent constipation. Regular checkup is necessary for postoperative patients until the wound is healed.

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