Anal Fistula Symptoms: 7 Signs and When to See a Doctor

One of the sentences I hear most often in my office is this: "My abscess had burst, I thought it was over. But my underwear has kept getting stained for months." The diagnosis of the patient who says this is more or less clear before the examination. Because this is precisely the most characteristic story of an anal fistula: a drained abscess leaves behind a thin tunnel between the bowel and the skin. That tunnel does not close on its own; it quiets down for a while, then starts discharging again.

I have been dealing with anorectal diseases for over twenty years, and I can say this with confidence: a fistula is a disease that does not hide its symptoms. The problem is that patients attribute these symptoms to other things — usually to piles — and wait for months.

The 7 most common symptoms of an anal fistula

To summarize briefly: recurrent discharge around the anus, an ache that worsens with sitting and bowel movements, a small hole in the skin that will not close, firmness or swelling in the area, itching and irritation, yellow-green stains on the underwear, and abscess flare-ups from time to time. Now let me unpack each of these from the patient's perspective.

1. A persistent, foul-smelling discharge

This is the fistula's signature. From the tunnel's skin-side opening seeps a purulent fluid, sometimes mixed with blood, and usually foul-smelling. A significant share of my patients have been using daily pads for months by the time they come to me. Do not be misled if the discharge stops now and then; as long as the tunnel stands, it comes back.

2. Pain that worsens with sitting and bowel movements

Unlike hemorrhoid pain, fistula pain is deeper, a dull ache. If the tunnel's opening becomes temporarily blocked, pus builds up inside and the pain turns into throbbing — a herald that the abscess is swelling up again.

3. A small hole in the skin that will not close

If you see a hole around the anus that looks like the head of a pimple but has not closed for weeks, that is no coincidence. Fluid emerging when you press on it with a finger is typical.

4. Swelling and firmness

Along the line of the tunnel, a cord-like firmness can be felt under the skin. During flare-ups the area becomes red and tender.

5. Itching and skin irritation

The constant seepage keeps the area moist; the skin responds with itching, patchy peeling, and burning. I have seen many patients who tried cream after cream for the itching while the real cause was never investigated.

6. Stains on the underwear

A simple but valuable sign: how often does the staining occur, and what color is it? If you note this down before your appointment, you make our job easier.

7. Recurrent abscess flare-ups

An abscess developing a second time in the same area almost always suggests an underlying fistula. In a patient who says "my abscess has burst three times," not looking for a fistula is not an option.

Can these symptoms be confused with hemorrhoids?

Very much so — and this is the misconception that wastes the most time. I roughly separate the differences as follows:

	Anal fistula	Hemorrhoids (piles)	Perianal abscess
Discharge	Continuous or recurrent, foul-smelling	Rarely, mucus-like	Once, in large amounts, when it bursts
Pain	Dull ache worsening with sitting	Burning during bowel movements	Throbbing, steadily worsening severe pain
Bleeding	Slight, mixed into the discharge	Frequent, bright red	Not prominent
Palpable finding	Hole in the skin, cord-like firmness	Soft lump	Tense, warm swelling

For a detailed comparison, see my article on the differences between fistula and hemorrhoids.

Which symptoms are an emergency?

If any of these three is present, do not put it off until tomorrow: a fever above 38°C, throbbing pain that worsens within hours, and redness around the anus spreading into the surrounding tissue. This picture can indicate that the infection is advancing into deeper tissues and requires intervention the same day.

Why is early diagnosis so important?

A fistula does not get simpler with waiting; it branches. A tunnel that is single and superficial at the start can develop side branches as the months pass. Most of the fistulas we catch early can be treated with laser, incision-free and as a day procedure; delayed, branched fistulas demand more arduous surgeries. The difference for the patient is not a matter of a few days' comfort, but of preserving the muscle structure.

The diagnostic side usually frightens patients, but the examination itself takes a few minutes. If needed, we order an MRI to map the tunnel — especially in recurrent or branched fistulas. I covered the stages and treatment options separately in this comprehensive guide.

Frequently asked questions

Does an anal fistula go away on its own?

No. The tunnel's inner surface becomes lined over time with skin-like tissue, which is why it does not close on its own. The occasional fading of symptoms is a quiet period, not healing.

Can there be a fistula without discharge?

Yes. If the tunnel's opening temporarily scabs over, the discharge stops; the pus building up inside makes itself known after a while, either with pain or with a new abscess.

Does a fistula turn into cancer?

This risk has been described in fistulas left untreated for many years, but it is rare. The real, present-day risk is recurrent abscesses and the tunnel branching, making treatment harder.

Which department should I go to?

General surgery — preferably a physician who focuses heavily on anorectal diseases (proctology). No enema or special preparation is needed before the examination.

My symptoms are mild; can I postpone the examination?

Even if the discharge and ache are mild, a suspected fistula requires an examination. In the early stage, treatment is both simple and incision-free options are on the table; waiting narrows the options.

If the symptoms sound familiar

If you are experiencing one or more of the above, after an examination at our clinic in Levent we will lay out a clear roadmap for you: is there a fistula, what type is it, and which method is appropriate. You can find all the treatment options on the anal fistula treatment page; for an appointment, call 444 8 623.

References

• American Society of Colon and Rectal Surgeons (ASCRS) — Clinical Practice Guidelines for Anorectal Abscess and Fistula, fascrs.org
• NHS — Anal Fistula patient information, nhs.uk
• Turkish Society of Colon and Rectal Surgery, tkrcd.org.tr