How is an anal fistula treated?

Anal fistulas are a painful and distressing condition, and can cause persistent and troubling symptoms for the patient. In his latest online article, renowned colorectal surgeon Professor Lee Dvorkin explains this condition in detail. He offers his expert insight into the symptoms, causes and treatment of fistulas. 

What are anal fistulas?

An anal fistula is an abnormal connection from the anal canal (back passage) to the surface of the skin near the anus. 

Fistulas are not common, but they can cause significant distress for patients who have them. Symptoms include pain and the discharge of pus, blood or faeces from the skin openings. 

If a fistula develops into an abscess, symptoms may include: 

• Pain
• Swelling
• Fever 

An abscess needs emergency surgery. 

How serious is a fistula?

Usually, patients with a fistula have persistent and troubling symptoms so, whilst it doesn’t not cause very serious problems, it can cause a real nuisance to patients and reduce their quality of life. Occasionally the fistula can develop into an abscess around the bottom. This causes severe pain and sepsis and will require emergency surgery to resolve it.

What’s the main causes of anal fistula?

Most patients (70-80%) do not have an underlying condition that causes the fistula. It arises because an infection develops around the anal muscles and within the anal glands which can become blocked.

For other patients, there are many other reasons  that can cause a fistula to develop. Pre-disposing causes include; Crohn's disease (where 30% of patients will develop a fistula), TB, HIV/AIDS, previous surgery or radiotherapy around the anus and rarely cancer of the rectum/anus.

Can a fistula heal by itself?

It is rare for a fistula to heal on its own.

How is it treated? Does it always require surgery?

Patients with a fistula should consult a colorectal surgeon with expertise in fistula surgery. They will carry out an examination to confirm the diagnosis and may request an MRI scan to get further information.

The treatment of anal fistulae will be different in each patient but will require surgery. All treatments aim to drain infection away, improve quality of life and, where possible, cure the fistula. If there is an underlying condition that caused the fistula, this will also need treating.

The type of operation suggested will depend on the location and severity of the fistula. With complex fistulas, more than one operation may be needed. With a simple fistula one of the most common operations is a fistulotomy.  In this, the infected tract is cut open. The wound created can take some time to heal but the success rate is 80-100%. Surgeons commonly don’t recommend this option in Crohn’s disease as there may be concerns about wound healing.

With complex fistulas which involve the anal sphincter muscle, there can be more of a risk of incontinence if the fistula is cut open.  So, the surgeon may put in a ‘seton’.  This is a thread which is passed through the fistula and out through the anus.

The most common type of seton is a loose seton.  This allows drainage of any infection and prevents abscesses forming. The seton may be removed later or can remain in place for some time.  Another option may be a ‘cutting seton’.  Here the seton is gradually tightened over time and this makes the seton ‘cheesewire’ slowly through the muscle closing the fistula as it moves.

Other treatment options for anal fistulas may include Collagen paste or plugs made of porcine (pig) tissue or laser treatment. These techniques are about 50% successful. Research is currently looking at injecting the fistula with stem cells, but more results are needed before this can be recommended routinely.

Professor Lee Dvorkin is a renowned consultant colorectal surgeon based in London, with over 25 years of experience. If you would like to book a consultation with Professor Dvorkin you can do so today via his Top Doctors profile.