Anal fistulas can cause unpleasant discharge and discomfort which can have a serious impact on patient’s quality of life. Fortunately, there is a wide variety of surgical treatment options, including some innovative techniques with good outcomes for patients. In this article, leading consultant colorectal surgeon Mr Charles Evans expertly outlines the diagnostic procedure and surgical techniques used to treat anal fistulas. He also gives insight on the recovery process after surgery.
What is an anal fistula and what causes it?
The official definition of a fistula is an abnormal communication between two epithelised surfaces (an abnormal connection or hole running between two organs or vessels). An anal fistula is an abnormal tract running from inside the anus to the external skin somewhere nearby. The patient will likely experience recurrent symptoms of discharge (bleeding or pus) and discomfort from the skin somewhere around the perianal area.
The most common cause for this is infection of the glands that are found within the anus that usually secrete fluid into the anal canal. This infection leads to a pocket of infected fluid building up, known as an abscess, which will then work its way to the skin edge to drain itself. This usually occurs around the bottom hole but can extend up to the scrotum in men or the vagina in women.
Once drained a connection can then be left between the skin edges and the anal glands leading into the anal canal and thus a fistula is formed. Other less common causes for fistula formation include specific bowel disorders such as inflammatory bowel dieases like Crohn’s disease and ulcerative colitis. Very occasionally, cancer or skin conditions or infections can also cause fistuals to form.
It is therefore recommended that you see a specialist to ensure the correct diagnosis is made.
How is an anal fistula diagnosed?
The first step is to take a history from the patient to discuss their symptoms. Often, the patient will have had an abscess at some point and perhaps even related surgery which required drainage. After that initial treatment, the symptoms will have improved and the abscess will have healed up but never fully gone away. There will likely be some kind of constant discharge from the area as well as discomfort.
When making a diagnosis, it is important to rule out other conditions that can cause the same troubles, such as inflammatory bowel disease or Crohn’s disease, for example. Therefore while taking the history, it is important that we hear about any other issues the patient may be having with their bowels, such diarrhoea or blood in the stool or if they’re having issues with tummy pains, weight loss or generally felling unwell.
We also need to hear about any other abscesses or skin infections in the groin or armpits. As well as ruling out conditions such as pilonidal sinus disease, where hairs become ingrown in the cleft between the buttocks, it’s important to check for signs of cancer. However, bowel, rectal or anal cancers are very rare and unlikely to be the cause behind these symptoms.
After a history has been taken, an expert will need to make an external examination. A punctum or a little mark that might be discharging is a sign that the patient might have a fistula. It may even be possible to feel the tract that runs towards the anal canal if the skin around it is touched. A specialist colorectal surgeon or proctologist will also need to look inside the bottom hole itself to see whether there is an internal opening and miscommunication between the inside of the anal canal to the outside.
To confirm the diagnosis, most surgeons would recommend doing both an MRI scan of the anal canal and an operation to physically examine the area under anaesthetic. For many patients, it is uncomfortable to make examinations in the clinic and it can be difficult for doctors to see what’s going on. Under anaesthetic, the doctor is able to more easily explore the area to examine any problems.
What are the treatment options?
The best treatment option for each patient depends on the stage of their fistula. If the patient only has an abscess, it may only be necessary to simply drain the sepsis and infection in an emergency operation. Afterwards, the abscess may heal on its own but in many cases, we place a seton, a string or a small plastic band that connects between the internal and external opening.
A seton acts a little like a nose piercing, running between the two sides and keeping the two openings open. They are prevented from closing up and therefore no infection can build up which could cause another abscess. Once the seton is in place, the fistula is fixed and is safe in that it is unlikely that the patient would develop another abscess or more perianal sepsis. Some patients are happy to live with the seton in place, a little piece of plastic which hangs out of the bottom, and no further treatment will be necessary.
If the patient wants the fistula to be fully cured, the options are quite varied and depend on the complexity of the individual fistula. The simplest and most successful way to cure them is called ‘laying it open’. In this technique, the surgeon cuts through the skin and tissue that go down to the fistula tract, which is then excised and allows the wound to heal back up towards the skin edge. This method is really effective for simple, low anal fistulas because they heal quickly, the cut isn’t too large and the anal sphincters aren’t damaged.
We try to use this type of surgery wherever possible and up to ninety per cent of patients who undergo this procedure have a successful cure with no further surgery. Certain more complex fistulas that run higher up within the anal canal can also be treated by being laid open, but this should be only undertaken by an expert in this field who has significant experience and training in this area.
There are other treatment options that don’t involve cutting down on to the fistula. These include using a collagen plug to block off the tract and fill the hole. The advantage is that no muscle of the anal canal needs to be cut but there is a risk the plug can fall out.
Newer techniques, such as electro-thermal or laser therapy attempt to obliterate the fistula tract and other more advanced surgical options are available avoiding cutting the anal sphincters. Unfortunately, all of these techniques do have a risk of recurrence of the fistula after treatment and should only be performed by specialists in these fields.
Is recovery painful after anal fistula surgery?
In many cases, patients can undergo the procedure as day-cases, meaning they don’t have to stay overnight. Naturally, the surgery will leave a wound that will require care in the weeks following the operation and pain killers and laxatives may also be needed for the first two weeks.
Patients also usually need input from a nurse and I personally review my fistula tract patients within two weeks to check they’re healing in the right direction. Generally speaking, the more complex the surgery, the more painful the recovery. The bottom is a sensitive area and there are some anaesthetic injections that can help to numb any pain before the patient goes home.
Can anal fistulas recur?
Anal fistulas can recur in some patients. This usually depends on the complexity of the fistula and the treatment. The less complicated and lower the fistula, the less likely recurrence is. After the ‘laying open’ procedure, around ten percent of patients may have a recurrence. In more complex operations, there is a higher recurrence rate. When deciding about treatment, it is important to be realistic and to balance the benefit of a successful operation against the risks of cutting the anal sphincters with the subsequent possible impact to bowel continence.
If you are concerned about the symptoms of anal fistulas or are requiring treatment, you can book a consultation with Mr Evans by visiting his Top Doctors profile.