At a glance
Anal fistula symptoms can range from obvious to subtle. Some people have clear, persistent discharge that makes the diagnosis straightforward. Others have intermittent symptoms that take longer to identify. This guide covers the common symptoms people describe and when they warrant professional assessment.
The main symptoms
Persistent discharge
The most characteristic symptom of a fistula is discharge from a small opening on the skin near the anus. People describe:
- Fluid or pus leaking from a spot near the anus — enough to stain underwear or require a pad
- Varying consistency — sometimes thin and watery, sometimes thicker
- Intermittent flow — discharge may come and go as the external opening opens and closes
- A stain on underwear as the first thing they noticed
The discharge is caused by fluid travelling through the fistula tract from the inside of the anal canal to the external skin opening. It is often the symptom that finally prompts someone to seek assessment.
Intermittent swelling and pain
Many people describe a cyclical pattern:
- The external opening of the fistula closes over
- Fluid accumulates in the tract
- Swelling, pressure, and pain develop in the area
- The opening re-opens and the fluid drains
- Symptoms improve
- The cycle repeats
This pattern can be mistaken for recurring abscesses, and in fact, the mechanism is similar — when the fistula tract cannot drain, it behaves like a small abscess.
Perianal irritation
The constant or intermittent moisture from drainage can cause:
- Itching around the external opening
- Skin breakdown from prolonged dampness
- Soreness from wiping or cleaning the area
- Redness around the opening
Pain with bowel movements
Some people with fistulas describe pain during bowel movements, particularly if the tract passes through or near the sphincter muscles. This can be mistaken for a fissure, and sometimes both conditions coexist.
Recurring abscess in the same area
If you have had a perianal abscess that was drained and then another abscess develops in the same area, this strongly suggests a fistula. The fistula provides a pathway for bacteria to re-infect the area.
Symptoms that may indicate a fistula vs other conditions
People often wonder whether their symptoms are from a fistula, a fissure, hemorrhoids, or something else. Some distinguishing features:
- Discharge from a skin opening is the most characteristic fistula symptom — fissures and hemorrhoids do not typically cause this
- Cyclical swelling and draining is suggestive of fistula
- Recurring abscesses in the same location strongly suggest a fistula
- Sharp pain during bowel movements is more typical of a fissure
- Bright red bleeding is more typical of hemorrhoids or fissures
These are general patterns, not diagnostic rules. Only a clinical assessment can determine what is causing your symptoms.
When to seek assessment
See a clinician if you have:
- Any persistent discharge from a spot near the anus
- Recurring swelling or pain in the perianal area
- A history of perianal abscess with new or ongoing symptoms
- Symptoms that are not improving with self-care
Early assessment and treatment of a fistula generally leads to better outcomes. The longer a fistula remains untreated, the more complex it can become.
What assessment involves
A clinician will typically:
- Ask about your symptoms, their pattern, and any history of abscess
- Examine the perianal area externally
- Perform a gentle digital rectal examination
- Possibly perform anoscopy (a brief look inside the anal canal)
- For complex or unclear cases, order an MRI to map the fistula tract
The examination is not comfortable, but it is necessary and usually brief. The information gathered directs the treatment plan.