This article is for information purposes only; it is not a substitute for an examination and a physician’s assessment.
An anal fistula typically passes through four stages: abscess → recurrent discharge → recurrent abscess → complex (branched) fistula. In the early stage the tunnel is single and superficial; in most cases it is closed with laser, without incision, as a day procedure. As it progresses it branches, requiring MRI and sphincter-preserving surgery. Whatever stage you are in, there is a treatment — but the easiest one was always in the stage before.
My one-sentence distillation of more than twenty years of treating fistulas is this: a fistula is not a malicious disease, it is an impatient one — while you wait, it works. The good news is that its work is not random: in nearly every patient, a fistula follows the same route. Know that route, and you can find your place on the map and see the bend ahead before you reach it. That is exactly why I wrote this guide.
First, the groundwork: what is a fistula and why does it form?
In brief: one of the secretory glands in the anal canal becomes blocked and inflamed, and an abscess forms; when the abscess drains, in roughly half of cases a permanent tunnel remains between the bowel and the skin. That tunnel is called an anal fistula, and because its inner surface becomes lined over time with skin-like tissue, it does not close on its own. For details see "What is an anal fistula?", and for the predisposing factors, the triggers article. Our real subject here is the tunnel's journey through time.
Stage one: the abscess — a loud beginning
The story usually opens with a swelling that builds over a few days, a throbbing pain that will not let you sit. This is the abscess stage, the most "honest" phase of the fistula — too painful to ignore. The abscess either bursts on its own or is drained by a physician; the patient feels relief and usually thinks "it has passed". The critical fact is this: the draining of the abscess is not the end of treatment, but the beginning of the possibility of a fistula. The smartest move at this stage is a follow-up examination within 4-6 weeks after the abscess drains; we see early whether a tunnel has remained.
Stage two: recurrent discharge — the silent tunnel
The picture that begins weeks after the abscess is familiar: a foul-smelling discharge that stains the underwear, stops and comes back, a dull ache that appears on sitting, a small hole in the skin that never closes. The tunnel is now established, but it is still single and mostly superficial. This is the stage where the treatment window is widest: examination is usually sufficient, MRI is rarely needed, and in suitable cases the tunnel is closed with the FiLaC laser, without incision, as a day procedure. Between the patient who comes at this stage and the one who comes two stages later, the difference in the treatment journey is — without exaggeration — weeks versus months. The full list of symptoms is in the symptoms article.
Stage three: recurrent abscess — the cycle is set
The tunnel's skin opening blocks off from time to time; the inflammation trapped inside forms an abscess again. By now the patient knows the picture by heart: every few months a swelling, throbbing, discharge, relief... Each cycle enlarges two things: the scar the inflammation leaves in the tissue, and the chance of the tunnel branching. We still have good options at this stage; but MRI now frequently enters the picture, and sometimes a few weeks of a loose seton are needed to prepare for laser. What I say to every patient who tells me "I have had three abscesses burst" I will write here too: do not wait for the fourth.
Stage four: complex fistula — the branched map
This is the result of years of neglect or of repeated failed interventions: the tunnel has developed side branches, sometimes wrapping around the anus like a horseshoe, and now involves the muscle in depth. Treatment is still possible at this stage — let me stress that, because most of these patients arrive believing "mine will never heal". What changes is not the possibility but the method: detailed mapping with MRI, sphincter-preserving techniques (LIFT, advancement flap, staged seton) and sometimes more than one session. The process is longer, but it reaches the goal.
Simple or complex? One table
| Simple fistula | Complex fistula | |
|---|---|---|
| Tunnel | Single channel, superficial course | Branched, deep or horseshoe course |
| Muscle involvement | Involves little of the muscle | Crosses the muscle in depth |
| Diagnosis | Examination usually sufficient | MRI essential |
| Treatment | Laser / fistulotomy, single session | Sphincter-preserving surgery, sometimes staged |
| Recurrence risk | Low | Markedly higher |
Treatment by stage: which method for which situation?
With an active abscess there is only one right answer: drainage — no definitive treatment is performed before the abscess is drained. For a simple, single-channel fistula our priority is muscle-friendly options: FiLaC laser where the anatomy is suitable; for very superficial tunnels, fistulotomy is also safe. Where branching is suspected, MRI comes first, then if needed a few weeks of a loose seton to drain the inflammation, followed by closure. For a complex fistula the plan is individual: LIFT, advancement flap and staged approaches are all on the table. The methods are described one by one on the treatment page, the risk side in the risks article, and the recovery side in the recovery guide.
Where am I on the map? A practical self-check
Which of these sentences describes you? "I have swollen up for the first time and it hurts badly" — stage one; come in today for drainage. "My abscess passed, but I have had on-and-off discharge for months" — stage two; the easiest treatment window, get examined this week. "It swells and drains a few times a year" — stage three; ask for an assessment with MRI. "It has gone on for years and I have had several operations" — stage four; start with mapping at an experienced center. Notice that none of them says "wait".
Frequently asked questions
How long does it take to move from one stage to the next?
There is no standard timetable — it can take months or years. Crohn's disease, diabetes and smoking speed the transition up. The only certainty is the direction: an untreated fistula walks forward, not back.
It was caught at an early stage; can I get through it without surgery?
If by "without surgery" you mean without incision — yes: most early-stage fistulas are closed with laser, incision-free. A completely non-procedural cure (with medication or creams) is not realistic at any stage; I explain why in the article on natural remedies.
I have a complex fistula; how many sessions until it is over?
The honest answer: it cannot be said without seeing the map. Some complex fistulas end with a single planned operation, others go in stages. After examination and MRI you can be given, if not a session count, then at least a clear roadmap.
Should I work out my own stage and come in accordingly?
No need — this guide exists to inform you, the examination to make it certain. Whichever stage you think you are in, the entrance door is the same: an examination.
Sources
- 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
Let us find your place on the map together; there is no need to wait for the next bend. Our clinic in Levent: 444 8 623.
Content owner: Yasir Gozu, MD
Published: June 3, 2025
Last updated: July 8, 2026
