Most fistulas drain pus onto your perineum, which can be bloody or foul-smelling. They form a tunnel from an abscess or anal canal to an opening on the skin around your bottom (anus).
Surgery for anal fistulas aims to cause minimal damage to the sphincter muscles that control when you poo. Your surgeon will advise which type of surgery is best for you.
Causes
Most anal fistulas form from clogged or infected glands inside the anus. Pus collects in a swollen pocket of tissue, which is drained by your doctor to relieve the pressure (abscess). A tunnel then forms between the clogged gland and the skin near the anus. The tunnel is called a fistula-in-ano. Fistulas can also develop from other causes. For example, some people with Crohn’s disease (an inflammatory disorder of the intestine) have them. They may also happen after radiation therapy for cancer near the anus.
Fistulas can be hard to diagnose because symptoms include pain, swelling and drainage from the rectum area or perianal skin. A GP can check for an anal fistula by looking at the skin around the opening of your bottom (anus). They might do a digital rectal examination, which involves gently inserting a gloved finger into your bottom.
An MRI or ultrasound test can create images of your anal canal and surrounding tissue, including the anus and rectum. A radiologist can then look at the images and identify any abnormalities. Your doctor may also order blood tests, X-rays or a colonoscopy, a procedure in which a flexible, lighted instrument is inserted into the colon via the anus. These tests can show whether you have anal fistula or other conditions. They can also help determine the cause of your fistula.
Symptoms
Just inside the anus are glands that make fluid. These can become clogged with pus and cause an abscess to form. The pus then tracks to the surface of the skin near the anus, creating a tunnel called a fistula. Fistulas are usually a result of an infection that didn’t heal right, but they can also be caused by cancer or injury to the anus. Tuberculosis, chlamydia, syphilis and sexually transmitted infections can also increase the risk of anal fistula.
Most people with anal fistula experience a constant throbbing pain that doesn’t stop, even when they aren’t using the bathroom. The pain is usually worse when they sit, move around or have bowel movements. Many people also have a discharge of foul-smelling, bloody or pus-like material from their anal opening that is associated with the pain.
Some patients with anal fistula develop a narrowing (stenosis) of the anal canal – the end of their bottom – which makes it harder to poo and can lead to constipation. This can be a serious medical emergency and you should seek urgent treatment.
Your GP will ask you about your symptoms and examine you. They may be able to see a hole in the skin of your bottom (anus) and can check for further signs of a fistula by inserting their finger into your anus. They will probably refer you to a specialist in colon and rectal problems for more exams or imaging tests such as X-rays or CT scans. They may need to do a procedure called a fistulogram or proctoscopy.
Diagnosis
Most anal fistulas develop from an abscess that drained, but it can happen because of other conditions like Crohn’s disease or side effects from medication. It also sometimes happens because of surgery or injury to the anal canal. Fistulas don’t heal on their own, so you need to have them treated.
Your GP will ask you about your symptoms and do a physical exam. The outer opening of the fistula is usually in the skin around your bottom (anus). Your GP may be able to feel it or see it. They might refer you to a specialist, such as a colorectal surgeon.
The specialists use different ways to find out how far the anal fistula has gone, but all involve a probe that goes inside your rectum and the injection of dye solution. They might also do a flexible sigmoidoscopy or colonoscopy, which are tests with an endoscope to look at your large bowel.
The most common treatment is to have surgery called a fistulotomy, which opens the fistula track so it can heal. The surgeon aims to do this without damaging the sphincter muscles that control when you poo (fecal incontinence). They might need to divide a small part of one of these muscles, but they try not to do too much because too much damage can lead to problems with your bowel control.
Treatment
Your doctor will use a physical exam of your anal area to see whether you have a fistula. They may also order X-rays or an ultrasound to find out its depth and direction. They will also try to determine if it is a complication of inflammatory bowel disease, such as Crohn’s or diverticulitis.
If you have a fistula, your doctor will advise you on how to manage it. It is important that you follow their instructions, and to finish all the antibiotics they have prescribed. You may need to take painkillers if you are uncomfortable, but never try over-the-counter medicines without first asking your doctor. Fistulas are often very painful and it can take a while for them to heal.
Surgery is usually required to treat anal fistulas as they do not heal by themselves. Your doctor will examine your anal canal and skin under anaesthetic to decide what type of operation is best for you.
They will probably choose the LIFT-plug or BioLIFT operation, which are both designed to minimise the discomfort of anal fistulas and reduce the risk of incontinence. It is important that you discuss the pros and cons of each procedure with your doctor to see which one is best for you. They may also suggest you have a fistulogram or proctoscopy to improve diagnosis of anal fistulas.
