Anal Fistula
An anal fistula is an abnormal tunnel that typically runs from the anal canal to an irregular hole in the perineum, the area between the anus and the genitals. The condition can cause extreme discomfort and may interfere with normal bowel function. There are two primary types of anal fistulas: high and low. The low fistulas are present in the lower anorectal area, while the high fistulas extend upwards beyond the region known as the anorectal sling. The higher fistulas are more serious because they can, if not appropriately treated, result in fecal incontinence.
Types of Anal Fistulas
Beyond the categorization of anal fistulas as high or low, these abnormal connections are subcategorized as:
- Blind, with only one end open
- Complete, with both external and internal openings
- Horseshoe, connecting to the anus or perineum in two places
- Incomplete, not connecting to any internal structure.
The most common fistulas are intersphincteric, meaning that the fistula follows a path between two sphincter muscles.
Causes of Anal Fistulas
Anal fistulas may form for a number of reasons. They may develop due to:
- Infection
- Inflammation
- Postsurgical complication
- Traumatic injury
- Inflammatory bowel disease, especially Crohn's disease.
As a matter of fact, anal fistulas are so commonly caused by Crohn's disease that patients with anal fistulas should be evaluated for the disorder.
Symptoms of Anal Fistulas
Anal fistulas may produce pain that becomes severe. Symptoms of an anal fistula may include:
- Painful bowel movements
- Anal or rectal bleeding
- Skin irritation around the anus
On occasion, there may be stool leakage from the abnormal opening into the perineum.
Diagnosis of Anal Fistulas
In order to diagnose an anal fistula, a digital rectal exam is performed. In addition, an anoscopy or sigmoidoscopy may be performed so that the doctor can better visualize the anus, rectum and lower large intestine. For these latter minimally invasive procedures, sedation is normally administered to prevent patient discomfort.
Treatment of Anal Fistulas
In some cases, anal fistulas can be treated with antibiotics and anti-inflammatory medications. Other options include the use of fibrin glue, collagen plugs, and setons (silk strings) to help drain infection. In most cases, particularly when an abscess prevents healing, a surgical procedure is necessary.