Anal Fistula

The term fistula in Latin means “a pipe or flute”. An anal fistula is a small tube or tunnel-like structure formed between the skin and the bowel's end near the anal region. It typically follows a prior infection of the anal glands, which might result in the formation of an abscess (a pocket of pus). Anal fistulas can be uncomfortable, itchy, and painful. They may also result in urgent and frequent bowel movements in some situations.

Anal Fistula: Types

Anal fistulas come in a variety of forms that can be categorized according to their anatomy and location.

  • Intersphincteric Fistula, which connects the inner and outer muscle layers. It is the most typical variety of anal fistula and is usually manageable.

  • Transsphincteric Fistula − This kind of fistula exits through the external sphincter muscle after passing through the inner muscular layer of the anus. This sort of fistula is more complicated and may be more challenging to treat.

  • Suprasphincteric Fistula − This kind of fistula extends above the sphincter muscle and could affect the rectum. It is a kind of fistula that is quite uncommon and might be difficult to treat.

  • Extrasphincteric Fistula − Extends outside the sphincter muscle. It is a kind of fistula that is quite uncommon and might be difficult to treat.

  • Complex Fistula − These fistulas might be challenging to cure since they have numerous branches or connections to the tissues around them.

Anal Fistula: Causes

The probable causes of the Anal fistula may include −

  • Injury to the anal region: Chronic trauma or injury to the anus can be a cause of anal fistula.

  • An anal fistula can develop as a result of other inflammatory disorders of the anus and rectum, such as ulcerative colitis.

  • Previous anal abscess, which is a collection of infectious material can be a cause.

  • Bacterial infections of the anal glands can cause anal fistula.

  • Anal fistulas may develop as a result of Crohn's disease, a chronic inflammatory bowel disorder.

  • Idiopathic − An anal fistula may occasionally form without any known cause.

Anal Fistula: Symptoms

The following are the major symptoms of Anal fistula −

  • Anal fistula patients may experience pain or discomfort in the anal region, especially when seated.

  • Swelling − The anal region may swell and become more sensitive to touch.

  • Anal fistulas can irritate the skin, itch, and produce redness and excoriation close to the anus.

  • Anal fistula sufferers could feel discomfort when passing stools.

  • Anal fistulas can also result in constipation because of the discomfort they bring on and also due to the dietary habits

  • Anal fistulas may result in drainage of blood or pus from the anus, which may be accompanied by an unpleasant odor.

  • Recurring abscesses: Individuals with anal fistulas can experience recurrent abscesses.

Anal Fistula: Risk Factors

The major risk factors of Anal fistula include −

  • Men are at higher risk than women to have anal fistulas.

  • Decrease in Immunity − Anal fistulas are more likely to form in people with immune system weaknesses, such as individuals with HIV or other immunocompromising diseases.

  • Smoking − Smoking can impair immunity and raise the possibility of anal fistulas.

  • Previous anal Abscess − Having a history of an anal abscess can make you more likely to get an anal fistula.

  • Crohn's Disease − Anal fistulas are more likely to form in those who have Crohn's disease.

  • Anal fistulas are more likely to form in people with inflammatory bowel illnesses, such as ulcerative colitis.

  • Genetics − An individual's risk of acquiring an anal fistula is increased if there is a history of the ailment in their family.

  • Age − People over the age of 40 are more likely to develop anal fistulas.

Anal Fistula: Diagnosis

To diagnose Anal fistula, some of the prominent methods are −

  • Physical examination and a review of the patient's medical history are typically the first steps in making the diagnosis of an anal fistula. In order to feel for any anomalies, the doctor may also perform a digital rectal exam, gently inserting a gloved finger into the anus.

  • An illuminated light source is used during an anoscopy to look inside the anus and rectum.

  • MRI or CT scan, can show the doctor the position and size of the fistula as well as any related abscesses.

  • Endoanal ultrasound − This examination creates images of the interior of the rectum and anus using high-frequency sound waves.

  • To rule out other conditions, a biopsy may be required in some circumstances.

Anal Fistula: Treatment

Major methods of treatment include the following −

  • Surgery − To treat an anal fistula, surgical intervention is frequently required. Depending on the location and size of the fistula, different surgical procedures may be used, such as fistulotomy, seton placement, or flap surgery.

  • Anti-Inflammatory Drugs and painkillers may be provided to aid with the swelling and pain brought on by the fistula.

  • Antibiotics − In some circumstances, an anal fistula that is infected may be treated with antibiotics.

  • Drainage − If an abscess has developed as a result of the fistula, the doctor might need to drain it. This can be accomplished by making skin incisions close to the anus.

  • Lifestyle Changes − avoiding spicy and irritable meals, taking warm sitz baths, and applying witch hazel compresses.

Anal Fistula: Prevention

Anal fistula can be avoided by taking the following preventive measures

  • Personal Hygiene − Preventing the development of an anal fistula by keeping the anal area dry and clean.

  • Anal Abscesses should be treated as soon as they appear in order to avoid them from developing into fistulas.

  • Manage Crohn's Disease or other inflammatory bowel diseases: If you have an inflammatory bowel disease, such as Crohn's disease, work with your doctor to control your symptoms and avoid the formation of anal fistulas.

  • Stop Smoking − Smoking can impair immune function and raise the chance of anal fistulas, therefore giving up may help lower that risk.

  • Healthy Lifestyles − Keeping up a healthy lifestyle will help maintain your immune system and lower your risk of having fistulas. This includes eating a balanced diet and exercising frequently.


An infected anal abscess ruptures, forming a channel between the anus and the skin, causing an anal fistula. Anal fistulas are frequently connected to disorders like Crohn's disease or other inflammatory bowel diseases, though their precise cause is not always recognized. Anal fistulas can cause serious problems, including sepsis and recurrent abscesses if they are not treated.

Anal fistulas are normally diagnosed through physical examination, imaging studies, and occasionally a biopsy. It's critical to practice good hygiene, treat anal abscesses as soon as they arise, take care of any underlying medical disorders, give up smoking, and keep a healthy lifestyle to lower the risk of getting an anal fistula.

Dr. Durgesh Kumar Sinha
Dr. Durgesh Kumar Sinha


Updated on: 17-Feb-2023


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