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All About Anal Fistula

01/06/2022

Anal fistula is a small tunnel that connects an infected gland inside the anus to the skin around the anus. These cause pain, swelling and skin irritation around the anus.

They usually begin as an infection in the anal glands that causes a collection of pus (abscess). When there is excessive pus build-up, a channel is formed which connects to the skin around the anus through which the pus drains.

Signs and Symptoms

The common symptoms of an anal fistula include:

Pus leakage at the anal opening
Bloody appearance of the pus and/ or foul smell from the discharge
Itching or redness around the anal opening
Pain during urination and passing stools
Fever and chills
Fatigue

See a doctor if you observe any of these symptoms.

Causes and Risk factors

Anal fistula often occurs due to the abscesses in the anus or clogged anal glands. Having certain health conditions can put you at risk of developing this. These include:

Crohn’s disease – an inflammatory disease of the intestine
Radiation treatment for cancer
Sexually transmitted diseases
Injury or trauma
Colitis
Tuberculosis or HIV
Diverticulitis – infection of the small pouches that can stick out of the side of the large intestine (colon)

Anal fistulas are very common in people with Crohn’s disease.

Diagnosis

If your healthcare provider observes any signs of anal fistula, you will be referred to a colon and rectal disease specialist. The specialist will begin with an examination of the area around the anus. They will check for fistula or pus leaks. Secondly, the health care provider will examine how deep the infection is. This is done by gently inserting a finger, pressing against the sore surface area of the anus.

After this, your examiner will check thoroughly if you have any risk-factors. Following a thorough physical exam, you may be advised any of the following tests:

Fistula probe: This tool is long, thin probe that is guided through the outer opening of the fistula. In this test, a special dye may be used to locate where the fistula opens up in the anus.
Proctoscopy or anoscope: These are special instruments used to look inside your anal canal.
Imaging tests: These may include an ultrasound scan, MRI scan or CT scan.

Treatment

Anal infection can be treated with antibiotics, but if there is a fistula, surgery is necessary to close it. These surgeries are done very carefully, so that they don’t cause incontinence. Some of the surgical treatments include:

Fistulotomy: This is the most commonly done surgery for anal fistulas. This involves cutting of the fistula open to allow it to heal from the inside out as a flat scar. This procedure cuts muscle around the anal opening (anal sphincter muscles).
Fibrin glue and collagen opening: This involves clearing the channel and stitching up the internal opening. Then, a glue made of fibrin is injected through the fistula’s external opening. The fistula tract can also be sealed with a collagen protein plug.
Seton placement: This involves placing a suture of silk or latex (rubber) called seton into the fistula which is slowly closed. This technique helps to drain the infection.
Advancement rectal flap: A flap is created from the tissue taken from rectum before removing the fistula’s internal opening. This flap is used to cover the hole. This procedure is opted when fistulotomy is considered for patients with higher fecal incontinence risk, and avoids cutting of sphincter muscles.
Endoscopic ablation: In this procedure, a tube with a camera at its end (endoscope) is inserted in the fistula. An electrode is then passed through the endoscope to seal the fistula. This procedure is very safe and effective .
Laser surgery: A radially emitting laser fibre treatment involves using laser beam to close the fistula.
Ligation of the intersphincteric fistula tract (LIFT) procedure: This procedure is opted when the fistula is passing through anal sphincter muscles, where a fistulotomy could be risky option. This involves cutting the skin above the fistula and moving the sphincter muscles apart. A seton is placed into the fistula tract to let the cut be wide open. The surgeon removes infected tissue and closes the closes the internal fistula opening i.e. sealing both ends.