Seton Insertion & Management

Overview

A seton (a thin, soft loop of thread or flexible tubing) is passed gently through the fistula tract — the tunnel that has formed — and tied loosely so that it sits in place without cutting. Think of it like a drain that keeps the tunnel open in a controlled way: it lets any infection drain away, prevents abscesses from building up, and allows the tissue around the sphincter muscle (the muscle ring that controls your bowel) to settle and strengthen over time. Mr Nguyen uses a loose seton as a long-term drain for high or complex fistulas where removing the fistula immediately would put your bowel control at risk. For fistulas related to Crohn's disease, a seton kept in place long-term is often the kindest ongoing strategy available.

Who needs this procedure?

• A high transsphincteric fistula — one that passes through a significant portion (more than 30%) of the external sphincter muscle, making it too risky to lay open in one go
• A complex or horseshoe fistula — one that branches or curves around both sides of the anal canal rather than running in a simple straight line
• A fistula associated with Crohn's disease, where inflammation makes the tissue fragile and definitive repair is rarely appropriate
• A fistula in someone whose sphincter muscle has already been weakened or injured — protecting what remains of your muscle control is the priority
• As the first step in a staged plan — the seton settles the infection and softens the surrounding tissue before a more definitive, muscle-preserving repair is attempted
• A fistula with an active infection (sepsis) that needs to drain and calm down before any further surgery is safe

Benefits

• Your sphincter muscle is completely left alone — there is no cutting of muscle during seton insertion, so your bowel control is protected throughout this stage of treatment
• Infection is kept drained and under control, preventing painful abscesses from forming while Mr Nguyen plans your next step
• Most patients live very normally with a seton in place — you can return to work, exercise, and daily life within a week
• The time the seton spends in place allows inflammation to die down, making any later muscle-sparing repair much more likely to succeed
• For Crohn's-related fistulas where a cure is not achievable, a long-term seton provides lasting comfort and drainage — a practical, dignified solution
• A day procedure — you go home the same day; no overnight hospital stay is needed

Risks & considerations

• The seton manages but does not cure your fistula: This is intentional — the seton is not meant to fix the fistula on its own. It is a bridge, keeping you comfortable and infection-free while the definitive plan is prepared. A cure will be attempted at a later stage when conditions are right.
• Some discomfort and mucus discharge: It is common to notice a small amount of mucous (clear or slightly cloudy fluid) around the seton. This is the drainage doing its job. Most people find it very manageable with a small pad in their underwear.
• Seton migration or breakage: Occasionally the thread shifts or frays. If this happens, it can be replaced under a brief anaesthetic — it is a minor procedure.
• Cutting setons — important to understand: There is a type of seton that is gradually tightened over time to slowly cut through the muscle. Mr Nguyen does not routinely use this technique. The loose drain seton he uses does not cut through muscle, so your bowel control is not at risk from the seton itself.
• Skin irritation: The skin around where the seton exits can become a little sore or red. A simple barrier cream keeps this comfortable.
• Infection around the tract: Occasionally a small abscess can develop alongside the seton despite it being in place. This is uncommon and treatable.

Before the procedure

• An MRI scan of your pelvis — a detailed imaging study that allows Mr Nguyen to map the full course of your fistula, including any hidden branches, before he places the seton
• No bowel preparation needed — no laxatives or enema required before this procedure
• A consent conversation with Mr Nguyen where he will walk you through the staged management plan in plain language, so you understand what this step means and what comes next

On the day

• You will be given a general anaesthetic (fully asleep) or occasionally a spinal anaesthetic (numb from the waist down) — you will not feel anything
• Mr Nguyen gently passes a thin probe through the fistula to confirm its path, then threads the soft seton loop through and ties it loosely — snug enough to stay in place, but not tight enough to cut
• If your fistula curves around both sides (a horseshoe fistula), small additional openings may be made to ensure all branches drain properly
• Local anaesthetic is injected to keep you comfortable when you wake up; you recover in the day-stay unit for a couple of hours
• Before you go home, you will receive written instructions explaining exactly how to care for and clean the seton — it is straightforward, and the nurses will go through it with you

Recovery & aftercare

• Days 1–2: Mild soreness around the seton and a little mucus discharge are completely normal — this is the drain working as intended. Take your pain relief regularly.
• Days 3–7: Most people are back to their usual routine within a week. The seton will simply become part of your everyday life.
• Ongoing seton care: Once a day — most easily in the shower — gently rinse around the seton with clean water or saline. This keeps the tract clean and prevents soreness. It takes about a minute and becomes second nature very quickly.
• Regular review with Mr Nguyen: You will be seen regularly so he can check how the tissue is settling. He will discuss with you whether the next step is a muscle-sparing repair or whether continuing with the seton long-term is the right choice for you.
• Planning the next step: Once inflammation has fully settled — usually several months after seton insertion — a definitive sphincter-preserving operation such as a mucosal advancement flap can be considered. Nothing will be rushed; the timing will be chosen together.
• For Crohn's patients: Your gastroenterologist and Mr Nguyen will work together. Keeping your Crohn's disease well controlled with medication gives any surgical treatment the best chance of success.
• 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.