Fistulotomy: procedure explained

At a glance

A fistulotomy is the most straightforward and effective surgical treatment for an anal fistula. It involves opening the fistula tract along its entire length, converting the tunnel into an open groove, and allowing it to heal from the inside out.

It has a high success rate but is only suitable for certain types of fistulas — specifically, those where the tract does not pass through a significant amount of sphincter muscle. This guide explains what the procedure involves, what happens on the day, and what the healing process looks like.

What the procedure involves

The anatomy

An anal fistula is a tunnel connecting the inside of the anal canal to the skin near the anus. The tunnel passes through tissue — and in some cases, through part of the sphincter muscle.

The surgical technique

1. The surgeon identifies the fistula tract — the internal opening (inside the anal canal) and the external opening (on the skin)
2. A probe is passed through the tract to confirm its path
3. The tissue above the tract is cut open, converting the tunnel into an open groove
4. The tract lining is removed or scraped (curetted)
5. The wound is left open to heal from the inside out

The wound is deliberately not stitched closed. This is because fistula tracts are prone to harbouring bacteria, and closing the wound could trap infection, leading to recurrence. Healing by secondary intention (from the inside out) allows the wound to fill naturally with healthy tissue.

When fistulotomy is appropriate

Fistulotomy is suitable for:

• Simple or superficial fistulas where the tract involves little or no sphincter muscle
• Intersphincteric fistulas that pass between the two sphincter muscles
• Low transsphincteric fistulas where only a small amount of external sphincter is involved

It is generally not suitable for:

• Complex fistulas involving a significant proportion of the sphincter
• Fistulas in people with existing continence concerns
• Crohn’s-related fistulas (usually managed more conservatively)

The decision about whether fistulotomy is safe depends on how much sphincter muscle would need to be divided. Your surgeon assesses this using examination, sometimes supplemented by MRI.

What happens on the day

Before the procedure

• Typically a day case — you arrive in the morning and go home the same day
• Fasting from the night before
• Pre-operative checks and paperwork
• Meeting the anaesthetist and surgeon

Anaesthesia

Fistulotomy is usually performed under general anaesthetic, though some are done with spinal or regional anaesthesia. The procedure is short, so the anaesthetic period is brief.

During the procedure

You are positioned appropriately (usually on your side or in the lithotomy position). The surgeon identifies and opens the tract, cleans it, and leaves the wound open. The entire procedure typically takes fifteen to thirty minutes.

After the procedure

• Recovery from anaesthesia in the post-operative area
• Pain assessment and medication
• Eating, drinking, and urinating before discharge
• Instructions for wound care, pain management, and follow-up
• Going home with a responsible adult

The healing process

What the wound looks like

The fistulotomy wound is an open groove in the skin between the anus and where the external opening was. It may be dressed initially. People describe it as:

• Open and raw-looking in the first days
• Gradually filling with pinkish-red granulation tissue (healthy healing tissue)
• Getting smaller over weeks
• Draining some fluid or blood initially

How it heals

Healing happens from the deepest part of the wound outward, and from the edges inward:

1. The wound bed fills with granulation tissue
2. The wound becomes shallower over weeks
3. Skin gradually grows across the surface from the edges
4. The wound closes completely

Timeline

• Week 1: the wound is open and draining. Pain is managed with medication and sitz baths.
• Weeks 2 to 4: noticeable improvement in pain. The wound is visibly smaller. Most people return to work.
• Weeks 4 to 8: continued healing. The wound is much smaller. Daily management becomes easier.
• Weeks 8 to 12 and beyond: many wounds are largely or fully closed. Deeper wounds may take longer.

Wound care

Daily wound care typically involves:

• Warm water cleansing (sitz baths or shower)
• Gentle drying — patting, never rubbing
• Keeping the area clean without over-cleaning
• Changing dressings or pads as needed
• Following specific instructions from your surgical team

Risks and complications

Continence

The main risk of fistulotomy is continence change, because the sphincter muscle is divided. For simple, low fistulas with minimal sphincter involvement, this risk is small. Your surgeon will assess this before recommending the procedure.

Recurrence

Fistulotomy has a low recurrence rate — generally under 10 percent for simple fistulas. The high success rate is one of the reasons it remains the preferred option when it is safely applicable.

Other risks

• Bleeding (usually minor)
• Infection (uncommon but possible)
• Slow healing
• Pain during recovery

The practical message

Fistulotomy is a well-established procedure with excellent outcomes for the right type of fistula. The trade-off is an open wound that takes weeks to heal and requires daily care. For most people, the weeks of wound management are well worth the resolution of a condition that may have been causing pain, drainage, and disruption for months or years.