What is an Anal Fistula?

What is an Anal Fistula?

Quick answer: An anal fistula is an abnormal channel that progresses from the skin around the anus or rectum into the inside of the anus, usually formed as a result

Medically reviewed by Op. Dr. Yasir Gözü · General Surgery and Proctology · Last updated: July 20, 2026

An anal fistula is an abnormal channel that progresses from the skin around the anus or rectum into the inside of the anus, usually formed as a result of the infection of glands that clean stool from the anus. These channels allow the discharge of infection outward and often form after the dr Anal fistulas can be chronic conditions and generally do not heal on their own without medical intervention. If left untreated, they can lead to p Anal fistulas can occur in both men and women and can appear at any age, but they are more common in middle-aged adults.

What Causes an Anal Fistula?

The most common cause of anal fistulas is the infection of the glands around the anus or rectum. These infections often lead to the formation of an abscess; an abscess creates an inflamed area in the surrounding tissue and can progress inward over time, turning into a fistula. Other causes include inflammatory bowel diseases like Crohn’s disease, sexually transmitted diseases, previous surgical procedures, or traumas. These conditions can disrupt the normal structure of the anal canal, setting the stage for fistula formation. In some cases, the exact cause of anal fistulas may be indeterminate; these are referred to as idiopathic fistulas.

What are the Symptoms of an Anal Fistula?

The symptoms of anal fistulas can vary but the most common symptoms include persistent p There can be a continuous or intermittent discharge of pus or blood from the fistula canal. This discharge can cause a bad odor and lead to personal hygiene problems. P Severe infections can lead to systemic symptoms such as fever and a general feeling of mal Chronic infections and recurring fistula problems can significantly lower the quality of life of affected individuals and necessitate the determination of effective treatment strategies.

How is an Anal Fistula Diagnosed?

The presence of an anal fistula can usually be understood through characteristic symptoms and signs. Patients often present to the doctor with compl These symptoms, especially in cases of recurring infections, are considered significant indicators of an anal fistula. Chronic infection symptoms and p In some instances, patients may notice the opening of the fistula or small swellings caused by the outwardly progressing channel. These signs play a crucial role in the initial diagnosis of an anal fistula.

How is an Anal Fistula Examined?

The physical examination for diagnosing and assessing an anal fistula is conducted to understand the patient’s symptoms in det The examination usually begins with a careful visual inspection of the anal region. The doctor looks for any swelling, redness, discharge of pus, or openings of the fistula in the anal area. As part of the physical examination, the doctor may carefully perform a digital rectal examination. This is important to assess whether the fistula channel progresses into the anal canal and the condition of the surrounding tissues.

If necessary, an anoscopy procedure can be performed for a more det Anoscopy involves the use of a small, lighted tube to examine the interior of the anal canal and rectum. This procedure allows for a better view of the internal structure of the fistula and the identification of other anal problems if present. In some cases, imaging tests such as magnetic resonance imaging (MRI) or endoanal ultrasound may also be recommended for a more comprehensive evaluation. These advanced diagnostic methods are used to assess the structure, length, and impact of the fistula on the anal sphincter muscles in det

Frequently Asked Questions

What is an anal fistula?

An anal fistula is an abnormal channel running from the skin around the anus into the inside of the anus, usually formed after infection of the glands that clean stool from the anus. These channels allow infection to discharge outward and generally do not heal on their own without medical intervention.

What causes an anal fistula to form?

The most common cause is infection of the glands around the anus, which often leads to an abscess that can progress into a fistula. Other causes include Crohn's disease, sexually transmitted diseases, previous surgery, or trauma, and in some cases the cause remains unknown.

What are the symptoms of an anal fistula?

Common symptoms include persistent discomfort and continuous or intermittent discharge of pus or blood from the fistula canal, which can cause a bad odor and hygiene problems. Severe infections can also cause fever and a general feeling of being unwell.

Who gets anal fistulas?

Anal fistulas can occur in both men and women at any age, but they are most common in middle-aged adults. Recurring infections and chronic fistula problems can significantly lower quality of life.

How is an anal fistula examined and diagnosed?

The doctor visually inspects the anal region for swelling, redness, discharge, or fistula openings, and may perform a digital rectal examination. If needed, anoscopy, MRI, or endoanal ultrasound can be used to assess the fistula's structure and its impact on the sphincter muscles.

Sources

• NHS - Anal fistula
• American Society of Colon and Rectal Surgeons (ASCRS) - fascrs.org

This article is for informational purposes only and does not replace a professional medical consultation. For diagnosis and personalized treatment, please book an appointment.