Fistulotomy

Overview

A fistulotomy works by gently opening up the fistula tract — the small tunnel that has formed — from its inside opening to its outside opening on the skin. Once laid open, the wound heals from the base upward, like a graze healing over, and the tunnel is gone for good. This approach works very well when the fistula runs through only a small amount of the sphincter muscle (the muscle ring that gives you control over your bowel). Before deciding that a fistulotomy is right for you, Mr Nguyen will arrange a special scan called an endoanal ultrasound — a painless internal scan — so he can see exactly where your fistula runs and how much muscle is involved. Choosing the right operation for your anatomy is everything.

Who needs this procedure?

• A low intersphincteric fistula — one that passes between the inner layers of the sphincter muscle, staying well clear of the main muscle bulk
• A low transsphincteric fistula — one that crosses through the outer sphincter muscle, but only through a small portion (less than 30%) of it
• A very shallow (superficial or subcutaneous) fistula close to the skin surface
• A fistula that has not closed after an earlier seton (a temporary thread drain) was removed
• A straightforward fistula in someone whose sphincter muscle has not been injured before
• A fistula that developed after a perianal abscess, provided the anatomy is favourable

Benefits

• Very high cure rate — more than 9 in 10 low fistulas are permanently fixed in a single operation
• Usually just one operation is all you need
• Nothing foreign is left inside your body — no plugs, no glue, no implants
• The tissue removed is sent to the laboratory (histology) to make sure there is no underlying condition such as Crohn's disease
• A day procedure — you go home the same day; no overnight hospital stay needed
• For truly low fistulas, the recurrence rate is lower than with more complex sphincter-saving techniques

Risks & considerations

• Bowel control (faecal incontinence): This is the most important risk to understand, and Mr Nguyen will discuss it with you in detail. The good news is that for truly low fistulas — where the tunnel barely touches the sphincter muscle — the risk is less than 5%, meaning more than 95 in 100 patients have no change in their bowel control. The risk is higher if more muscle is involved, which is exactly why careful scanning before surgery matters so much. If there is any doubt, Mr Nguyen will recommend a different, muscle-sparing approach instead.
• Wound healing time: The wound is left open to heal naturally from the inside out — think of it like a graze. This is deliberate and is actually how the fistula closes for good. For most low fistulas, healing takes 4–8 weeks. It can feel slow, but steady progress is normal.
• Recurrence: Roughly 5–10 in 100 fistulas come back after fistulotomy. If yours does, further treatment options are available.
• Bleeding: Some bleeding around the wound in the first few days is normal and usually minor. Heavy bleeding is uncommon.
• Pain during healing: The area will be sore, especially in the first week. Warm sitz baths (sitting in a shallow bath of warm water) and regular pain relief make a real difference.
• Minor change in anal shape: As the wound heals, a small groove or notch may form at the site — this is a cosmetic change only and does not affect how the bowel works.

Before the procedure

• An endoanal ultrasound (a small internal scan) or MRI scan to map your fistula precisely — this is essential before any decision is made about surgery
• No bowel preparation needed — you do not need to take laxatives or undergo an enema beforehand
• A thorough consent conversation with Mr Nguyen, where he will explain the risk of incontinence specific to your anatomy in plain language

On the day

• You will be given a general anaesthetic (you will be completely asleep) or occasionally a spinal anaesthetic (numb from the waist down); you will feel nothing during the operation
• A thin probe is gently passed through the fistula tunnel to map its course from the inside opening to the outside opening on your skin
• The tunnel is then opened along its length using a precise surgical tool, converting it into a shallow open groove
• The tissue lining the groove is sent to the laboratory to check for any underlying condition
• Local anaesthetic is injected into the area to keep you comfortable when you wake up
• You recover in the day-stay unit for a few hours, then go home with written instructions on how to look after your wound

Recovery & aftercare

• Days 1–2: The area will be sore — this is completely expected. Take your pain relief regularly (do not wait until you are in pain to take it), and sit in a warm shallow bath (a sitz bath) a couple of times a day. This soothes the wound and keeps it clean.
• Days 3–7: Pain should start easing. It is important to gently irrigate (rinse) the wound as instructed — keeping it clean helps it heal from the inside out. You will be shown exactly how to do this before you leave hospital.
• 4–8 weeks: Most low fistulas are fully healed within this window. Progress is gradual — you will notice the groove slowly becoming shallower week by week.
• Eat plenty of fibre (fruits, vegetables, wholegrains) and drink enough water throughout your recovery. Soft, easy-to-pass stools reduce discomfort and protect the healing wound.
• Call the rooms if you develop a fever, notice worsening rather than improving pain, or the wound looks like it is opening up rather than closing — these are signs worth checking promptly.
• A follow-up appointment with Mr Nguyen is routinely booked 2–6 weeks after your operation, depending on the type of surgery. This review is provided at no charge to you.

Related patient guides

Easy-to-read articles written for you and your family on topics related to this procedure.