Colorectal Health

Anal Fistulas: Common Causes

An anal fistula is a small passage that forms between anal canal or lower part of rectum and skin around anus. Treatment of anal fistulas always involves surgical procedures aiming to get rid of fistulas while preserving the anal sphincter muscles.

What Is an Anal Fistula?

An anal fistula is a small passage that connects the inside of the anal canal or lower part of the rectum to the skin surrounding the anus.

The anus is the final part of the digestive tract through which the faeces are removed from the body. Inside the anus, there are special glands that secrete mucus. Sometimes, these glands may get clogged and infected forming an abscess which in turn, may transform into an anal fistula over time.

Causes of an Anal Fistula

In most cases, an anal fistula is caused by blocked and infected anal glands and perianal abscesses. Other conditions that may cause an anal fistula include the following:

• Inflammatory bowel disease (IBD): Crohn’s disease
• Chronic diarrhoea
• Cancer
• Sexually transmitted diseases (STDs)
• Tuberculosis

Symptoms of an Anal Fistula

Common signs and symptoms of an anal fistula are:

• Pain, redness and swelling around the anus
• Foul-smelling pus drainage through the opening on the skin near the anus.
• Fever and chills
• Fatigue

How is an Anal Fistula Diagnosed?

To diagnose an anal fistula, your specialist doctor will need to examine the area around the anus. They will search for an opening or hole on the skin. Then, the specialist will evaluate how deep the canal is and identify in which direction it is going.

In some cases, anal fistulas are not detectable on the skin surface. In this instance, your specialist may need to conduct additional tests, such as:

Anoscopy

A procedure where a scope is used to check the interior of the anus and rectum.

Imaging Tests

These usually include an ultrasound, computer tomography (CT scan) or magnetic resonance imaging (MRI) to create images of the anal tract for better visualisation.

What are the Treatment Options for an Anal Fistula?

Most anal fistulas require surgery that is performed by a colorectal surgeon. Depending on your particular condition, Dr Sim may offer you the following surgical options:

Fistulotomy

An operation where your surgeon will open up the abnormal connection, transforming it into an open groove. This will allow a fistula to heal from the inside out.

Bioprosthetic Plug

This advanced procedure involves filling the fistula tract with a special tissue that will naturally dissolve over time.

Fibrin Glue

During this procedure, your colorectal surgeon will “seal” the fistula canal with special glue.

Ligation of Intersphincteric Fistula Tract (LIFT)

This technique involves making an incision around the anus, locating the fistula tract between sphincter muscles and tying off the two openings of the tract.

Seton Techniques

If your fistula is complex and passes through a large portion of the anal sphincter, your surgeon may recommend inserting a seton. A seton is a non-absorbable suture that is inserted in the fistula for at least a few weeks. It allows the pus to drain and facilitates some healing without the need to cut the sphincter muscles. Often a subsequent procedure is required if a patient wishes to have the seton removed in the future.

Advancement Flap Procedure

During this surgical treatment, the fistula is scrapped out and an internal opening is covered using a flap created in the rectum.

Laser Surgery

This surgery involves utilising a small laser beam to seal the fistula.

Video-Assisted Anal Fistula Treatment (VAAFT)

This advanced surgical technique is applied to treat complex fistulas. During this procedure, the surgeon will insert a video scope into the external opening of the fistula going all the way through the tract and follow it to the internal opening. This allows the surgeon to potentially locate the internal opening and clean out and ablate the canal with a brush and a probe respectively through the video scope. The internal opening will be closed via various methods if it can be located.

FAQs About Anal Fistula Treatment

How to prepare for anal fistula surgery?

• Avoid excessive smoking and drinking alcohol
• Depending on your particular case, you will receive instructions from Dr Sim regarding preparation diet, fasting and medications you may need to take or avoid.
• You may be given a fleet enema to help empty your rectum before the surgical procedure.

How long will I stay at the hospital?

Typically, fistula surgeries are performed on an outpatient basis, meaning that you do not have to stay at the hospital overnight. However, patients with complex or infected fistulas may need to stay at the hospital for a short period of time. Some cases require more than one surgical treatment.

What is the after-care?

The level of discomfort and pain after surgery varies from mild to moderate. Your surgeon may inject a local anaesthetic (lidocaine) or prescribe pain pills. Patients are usually recommended to take stool softeners post-surgery in the first few weeks after surgery.

After-care differs depending on the type of surgery performed.  Patients with open wounds would require shower spray to clean the wound. while VAAFT cases would require daily flushing of wounds for a couple of weeks.

What are the possible complications after the surgical procedure?

Just like any surgical procedure, treatment of anal fistula has a potential risk of complications which mainly include:

• Infection
• Bowel Incontinence
• Recurrence of the anal fistula