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Anal Fistula | Fistulotomy

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What is an Anal Fistula?

Anal fistula refers to an abnormal connection between the inside of the anus to the skin around the anus. Anal fistula commonly presents with discharge or pain around the anus. Sometimes, patients can feel a swelling or lump at the anus or have itch (i.e., pruritus ani). This common condition is usually a result of cytogenic glands that get infected in the anus. 

Although the triggers for this condition remain elusive, treatment can still be instilled successfully when an accurate preoperative diagnosis is made. There are many types of anal fistula, or professionally termed fistula-in-ano (FIA). This classification is based on Park’s classification. 

(reference: https://bjssjournals.onlinelibrary.wiley.com/doi/10.1002/bjs.1800630102)

Do I have an Anal Fistula?

Well, the common symptoms of anal fistulas are pain, itching, bleeding, and discharge. 

Some patients can even feel a swelling around the anus when they shower. Others present with an abscess which is extremely painful and usually present themselves to a General Practitioner or at the emergency department.  

Recurrent anal infections can also be a sign of an underlying anal fistula. If an abscess has been successfully treated and has now recurred, it is important to exclude an underlying fistula. 

What are the Different Types of Anal Fistulas?

There are four types of anal fistulas: intersphincteric, transsphincteric, suprasphincteric and extra-sphincteric. Each type is identified by its location and the path of the fistula.

  • Intersphincteric fistulas begin in the sphincter muscles of the anus and travel through the tissue that separates the inner and outer sphincter muscles. This type of fistula is the most common and are usually simple fistulas.
  • Transsphincteric fistulas run through the sphincter muscles and into an area of tissue called the intersphincteric space. This type of fistula is more complex than intersphincteric fistulas and can be related to previous surgery or trauma.
  • Suprasphincteric fistulas travel through the muscles of the anus and into the fatty tissue that lies outside of the sphincter muscles. This type of fistula is very uncommon and is a complex form of anal fistula.
  • Extrasphincteric fistula is a communication outside the confines of the anal sphincter. The hypothesis is an abnormal connection that resulted from a supra-levator abscess from diverticular disease or inflammatory bowel disease. Like the suprasphincteric fistula, this is also very rare and similarly complex. 

Regardless of the type of anal fistula, it is important to seek medical advice. Treatment options vary depending on the type and severity of the fistula. Surgery remains to be the most effective treatment and is recommended for most fistulas. In some cases, medications, such as antibiotics and antifungal medicines, may be prescribed.

What are the Causes of Anal Fistula?

By far, the most common cause of an anal fistula is an infection or inflammation of the anal glands also known as cryptogenic glands. (Not cryptocurrency!) This is often caused by clogged anal glands or an abscess. Clogged anal glands can happen when the small glands become blocked by hardened stool or infection. 

When the glands are blocked, they become swollen and can become filled with pus. This is known as an anal abscess. If the abscess is not treated, it can spread and create a tunnel between the rectum and the skin near the anus. This is an anal fistula.

Other, much less common, conditions that can cause an anal fistula include Crohn’s disease, radiation, trauma, sexually transmitted diseases, tuberculosis, diverticulitis, and cancer.

  • Crohn’s disease is an inflammatory disease of the intestine. It can cause inflammation, scarring and ulcers in the digestive tract. This can weaken the walls of the intestine and cause an anal fistula. If this condition is suspected, we usually require a colonoscopy or MRI imaging or both to be done following the initial consultation.
  • Radiation is often used as a treatment for cancer. However, radiation can also damage the tissues of the rectum and anus, leading to an anal fistula. Radiation related fistula can be very difficult to manage as the tissue is usually indurated or hardened. Healing is also impeded in irradiated tissue. 
  • Trauma to the anus or rectum can also cause an anal fistula. This may be the result of a blunt force, such as a kick or fall, but usually it results from a sharp object penetrating the tissue. 
  • Sexually transmitted diseases such as syphilis and herpes can also cause an anal fistula. These infections can cause inflammation and ulceration of the rectum and anus, leading to an anal fistula. In such patients, it is needed to check for concomitant retroviral infection as well. 
  • Tuberculosis can also cause an anal fistula. Tuberculosis is an infection that can spread through the bloodstream and cause inflammation of the rectum and anus. This can lead to an anal fistula.
  • Diverticulitis is a disease in which small pouches form in the large intestine and become inflamed. This can weaken the walls of the intestine and lead to an anal fistula. 
  • Finally, cancer itself can also cause an anal fistula. Cancer in the rectum or anus can spread to the surrounding tissues and create a tunnel between the rectum and the skin near the anus.

To determine the underlying cause, it is important to see a doctor as soon as possible to get an accurate diagnosis.

How is Anal Fistula Diagnosed?

In order to properly diagnose an anal fistula, your doctor will need to conduct a physical examination of the area around the anus. During this examination, they will look for any visible openings (the fistula tract) on the skin. They will also try to determine how deep the fistula tract is, and in what direction it is going. 

As seen from above, depending on the suspected diagnosis, additional tests may be needed to diagnose an anal fistula or exclude underlying causes. These tests may include a colonoscopy, an ultrasound, or an MRI. Do refer to the section under colonoscopy for more information. The ultrasound or MRI mainly helps to  delineate the fistula tract and determine the surgical anatomy for pre-operative planning. 

In some cases, your doctor may recommend a procedure called Exam Under Anesthesia (EUA) to diagnose the fistula. This procedure is performed in an operating room and involves the use of anesthesia. During the procedure, your doctor may use a thin, lighted tube called an anoscope to examine the area around the anus, and they may also need to perform a biopsy to confirm the diagnosis.

Once the diagnosis is confirmed, your doctor will be able to recommend a treatment plan based on the type and severity of your fistula. Treatment options may include antibiotics, fistulotomy and other types of surgery. If you think you may have an anal fistula, it is important to seek medical attention as soon as possible. Early diagnosis and treatment can help prevent serious complications from developing.

What are the Treatment Options for Anal Fistula?

Fortunately, there are a variety of treatment options available for those dealing with an anal fistula. Depending on the complexity of the fistula, your age, and any underlying medical conditions, your surgeon will recommend one of the following treatment options:

1. Fistulotomy or Fistulectomy

This procedure refers to the incision or excision of the fistula tract, thus leaving an open perianal wound for it to heal with secondary intent. This procedure involves the cutting of a part of the anal sphincter and thus incontinence is a possible complication of this surgery. The risk is often mitigated by accurate delineation of the anatomy and limiting this approach to the low/ simple group of FIA.

2. Seton Insertion

A seton is a soft rubber tubing that is inserted through the entire fistula track. Seton insertion surgery has 2 main types. The draining seton is used to just keep the track open and lowers the risk of infection but does not definitively treat the underlying fistula. The cutting seton on the other hand, aims to externalize the FIA through progressive tightening. This method usually requires multiple procedures, hence a prolonged treatment course, and can also induce pain during the treatment period.

3. Ligation of Intersphincteric Tract (LIFT)

This is a procedure that aims to interrupt the abnormal connection by suture ligation. It spares the cutting of the anal sphincters unlike fistulotomy or fistulectomy and has a lower incidence of incontinence. It is suitable for both simple and complex FIA. This technique however is associated with a higher risk of recurrence of fistula. 

Primarily, the ligation depends on the accurate identification during surgery and also the healing ability of the surrounding tissue. This will require a detailed preoperative workup and selection of the best timing for the operation for the most ideal outcome. 

4. Advancement Flap

The endoanal advancement flap involves elevating a flap of healthy tissue to cover the internal opening of the fistula tract. This procedure requires more extensive dissection around the anus and thus has a higher procedure related risk. This is usually considered for complex fistulas or for patients who have failed standard treatment. 

There are different types of flaps and each is used depending on the location of the fistula and the status of the surrounding tissue. An experienced surgeon is needed for such a procedure and the recovery period is also longer than all the other surgeries. 

5. Laser

Using a laser probe, the entire track is cauterized and promotes fibrosis and healing. This avoids the need of cutting the anal sphincters and is an option for relatively simple FIA with a possible history of incontinence or weak sphincters. The lack of long term data on this procedure suggests a need for careful selection of patients who are suitable for this operation.

6. Others

Due to the complexity and variants of different FIAs, there are many other options available including decompression and drainage (DADS), Video Assisted Anal Fistula Treatment (VAAFT) and combination of above approaches. Given the myriad of options, it is important to have adequate pre-operative assessment and a discussion with the primary surgeon for shared decision making.

What is the Post-Op Care for Anal Fistula Surgery?

When it comes to post-operative care for an anal fistula, it is usually very simple and can all be performed at the comfort of your own home. The key steps are regular shower spray washing after every bowel movement and maintaining a clean and dry dressing over the surgery site. 

Most patients, however, can be discharged from the hospital the same day or the day after surgery. Following surgery, the patient may experience mild to moderate discomfort for the first week. This can usually be managed with prescribed pain medication. It is important to follow the instructions given by the doctor and take the medication as directed.

Depending on the type of fistula and the type of treatment, the post-operative care instructions may also vary. For fistulotomy and fistulectomy, advice on specific areas of irrigation are sometimes crucial to maintain a clean postoperative environment for healing. 

After VAAFT and LIFT procedures, it is important to have regular bowel movement and pay attention to any discharge from the surgical site. An early infection can be effectively treated with antibiotics easily. 

If fibrin glue or fistula plug has been used, the wound should require minimal care. The patient may want to use a small amount of antiseptic cream to prevent infection. It is important to continue regular follow-up appointments and follow the doctor’s instructions for post-operative care.

Frequently Asked Questions

  • What are the primary causes of anal fistula?

    The most common cause of an anal fistula is an infection in the anal glands. These result in an abscess which continues to burrow through the anus into the external perianal skin resulting in the anal fistula. There are also other less common causes like trauma, Crohn’s disease and rarely cancer. These will require a consultation to determine the underlying cause.

  • Can a fistula heal on its own?

    Anal fistulas tend to persist and spontaneous healing is not common. In the event that there is an active infection like an abscess, treatment of the abscess can sometimes lead to the spontaneous healing of the fistula. Hence during the surgery for a perianal abscess, it is recommended that the abscess should be drained first and the fistula can be left alone for a staged procedure.

  • Is it possible to live with a fistula forever?

    Although this is possible, this is not medically advisable. The main reasons being recurrent perianal infections and symptoms when left alone. Furthermore, there is a risk of cancer formation in long standing fistulas. This risk though not clearly documented has been observed in case reports and clinical practice.

  • Can a fistula be cancerous?

    Fistulas are very rarely due to cancer. Most fistulas are invariably benign and do not bear any cancer cells in them. Those that are associated with cancer have an associated mass or are very long-standing.

    The long-standing fistulas that bear cancer are those usually there for many years and they classically produce mucin as a prominent feature. If this is suspected, a biopsy is usually needed to confirm the diagnosis.

  • How can I detect a fistula?

    Clinically, a fistula can be diagnosed on examination of the perineum and anus area. It will appear like a small swelling or a pimple-like lesion on the skin around the anus. The fistula can also be palpated as a linear communication under the skin from the external opening to the anal canal.

    In cases where an abscess has already formed, then a painful fluctuant swelling can be the main finding in the region around the anus. Fistulas can also be detected as an incidental finding when a patient is undergoing a colonoscopy or sigmoidoscopy.

  • How do I know if I have a fistula?

    Anal fistulas tend to have the following symptoms:

    1. Perianal swelling
    2. Perianal itch
    3. Discharge from the anal region
    4. Perianal pain/discomfort
    5. Blood in stools

    Although these symptoms can be due to anal fistula, they can also point to other diagnoses like piles and anal fissures. Hence it is important to see a doctor to achieve an accurate diagnosis.

  • Can hemorrhoids cause fistula?

    Hemorrhoids and anal fistulas are not related and they have different pathophysiology. Thus, hemorrhoids do not cause fistula. However, the presence of constipation can predispose to both conditions. Thus both conditions can co-exists even though the symptoms can be pertaining to a predominant condition.

  • What is the best treatment option for anal fistula?

    Surgery remains the best form of treatment option for anal fistula. The best surgery should be discussed with the primary surgeon and it also depends on the type of fistula with the availability of the surgeon.

    For simple fistulas, fistulotomy and fistulectomy carries the best overall results in terms of decreased recurrence and recovery from surgery. For complex fistulas, many options are available and the optimal outcome depends on the location of fistula and the healing ability of the surrounding tissue.