Anal Fistula – Symptoms and Causes
Overview
An anal fistula (fistula-in-ano) is a tunnel that forms between the inner anal canal and the skin surrounding the anus. The anus is the muscular opening where stool leaves the body at the end of the digestive tract.
Most anal fistulas develop from an infection in an anal gland. This infection creates an abscess (collection of pus) that either drains naturally or requires surgical drainage.
After drainage, a tunnel remains connecting the infected gland or anal canal to an opening in the skin around the anus.
Common causes:
- Infections in anal glands
- Drainage of anal abscesses
Treatment options:
- Surgery (most common approach)
- Nonsurgical alternatives (in certain cases)
The specific approach depends on the fistula’s location, complexity, and the patient’s overall health.
Signs to Watch For
An anal fistula often shows visible symptoms on the skin near the anus.
You might notice a small opening that becomes red and swollen. This opening may release pus, blood, or even small amounts of stool.
Pain is common, especially when sitting down or during bowel movements. Some people also develop fever when the infection becomes more severe.
These symptoms won’t go away without treatment, so it’s important to see a doctor if you notice these signs.
Causes
Anal fistulas typically develop from an infection in an anal gland. When infection occurs, an abscess (pocket of pus) forms near the anus. This abscess may drain naturally or require surgical drainage.
After drainage, a tunnel-like pathway often develops under the skin. This tunnel connects the infected anal gland or anal canal to an opening on the skin surrounding the anus—this is the fistula.
The classification of fistulas depends on their relationship to the sphincter muscles around the anus. These muscles control bowel movements by opening and closing the anal opening.
Risk Factors
Several factors can increase a person’s chance of developing an anal fistula:
- Having a previously drained anal abscess
- Living with Crohn’s disease or other inflammatory bowel diseases
- Experiencing trauma to the anal area
- Having infections in the anal region
- Undergoing surgery or radiation treatment for anal cancer
Anal fistulas typically affect adults around age 40, though younger individuals may develop them, particularly those with Crohn’s disease. Men face a higher risk of developing anal fistulas compared to women.
Possible Problems
Even with good treatment for anal fistulas, problems can sometimes happen. Knowing about these issues helps patients prepare for what might occur during recovery.
Recurrence is one of the main concerns after treatment. This means the abscess or fistula comes back, even after it seems to be fixed. Patients should watch for signs like renewed pain, swelling, or drainage in the anal area after healing appears complete.
Fecal incontinence is another potential complication following surgical treatment. This condition means a person may have trouble controlling bowel movements. The severity can range from minor leakage to complete loss of control. This happens because:
- Surgery might affect muscles that control bowel movements
- Nerve damage can occur during procedures
- The anal sphincter (the ring of muscle controlling the anus) may be cut during some treatments
The risk of incontinence varies based on:
| Factor | Impact on Risk |
|---|---|
| Fistula location | Higher risk with complex tracks |
| Surgical approach | Some methods have lower risks |
| Patient’s age | Older patients may face higher risks |
| Existing muscle tone | Poor muscle strength increases risk |
Follow-up care is essential after treatment.
Patients should attend all scheduled appointments and report any new symptoms promptly to their healthcare provider.
