Lateral Internal Sphincterotomy

Overview

A lateral internal sphincterotomy works by releasing the tight, constant spasm in the internal anal sphincter — the ring of muscle that controls your anal opening — that is preventing your fissure from healing. When this muscle is too tense, it squeezes off the blood supply to the wound and traps it in a repeating cycle of pain and re-injury. By gently easing that tension, blood flow returns to the area and the fissure finally gets the chance to heal properly.

Mr Nguyen performs a carefully tailored, limited sphincterotomy — meaning he divides only as much of the muscle as is necessary to achieve healing, and no more. This precision is why the healing rate is high and the risks are kept as low as possible. The whole operation is done under a general anaesthetic, and you go home the same day.

Who needs this procedure?

A lateral internal sphincterotomy is usually recommended when other treatments haven't been enough. It may be right for you if:

• Your fissure has been there for more than 6 weeks and hasn't healed despite using prescription creams or trying a botulinum toxin (Botox) injection
• Your fissure keeps coming back after non-surgical treatment
• Pressure testing (anorectal manometry) has shown your internal sphincter muscle is significantly tighter than normal
• Your fissure pain is severe enough to affect your daily life, sleep, or ability to work
• You would prefer a single, definitive procedure rather than ongoing or repeated treatments

Benefits

• The highest healing rate of any fissure treatment — more than 95 in every 100 fissures are healed at one year
• A single day procedure under general anaesthetic — you go home the same day
• Fast relief — most people notice the deep, agonising fissure pain starting to ease within just a few days of surgery
• Long-lasting results — the fissure comes back in fewer than 5 in every 100 people
• The incision is small and placed to the side of the anal canal (not at the fissure itself), so healing is straightforward
• A well-established operation with decades of research behind it — this is not a new technique

Risks & considerations

It is important to us that you go into this procedure with a clear picture — including the risks. The most important one to understand is the possibility of a change in bowel control, and we want to give you an honest but reassuring explanation of what that actually means in practice.

• Difficulty controlling wind (passing flatus) — this happens in around 5 to 15 in every 100 people. For the great majority, it is minor and temporary — settling within a few months as the muscle adjusts to the change. Permanent, significant difficulty is rare.
• Difficulty controlling liquid stool — this affects fewer than 5 in every 100 people, and is usually temporary. Because Mr Nguyen makes a carefully limited, precise cut, he keeps this risk as low as possible.
• Wound infection — uncommon, occurring in fewer than 2 in every 100 people. It is treated with antibiotics if it occurs.
• The fissure coming back — this happens in fewer than 5 in every 100 people over the long term.
• Bleeding — some minor bleeding at the wound is normal and expected. Significant bleeding is rare.
• Fistula (an abnormal channel forming near the wound) — a very rare complication.

Please raise any questions or concerns about these risks when you meet with Mr Nguyen — he will go through all of them with you in as much detail as you need, and there is no such thing as a question too small.

Before the procedure

• No bowel preparation (enema or laxative) is required before this procedure — that is one less thing to worry about
• Please arrange for a trusted adult to drive you home — you won't be able to drive yourself after a general anaesthetic
• Before your procedure, Mr Nguyen will take you through the benefits, risks (including the continence risk explained above), and what to expect. Please bring any questions — he is happy to take the time
• You can continue using any prescription cream or ointment right up until the day of your operation

On the day

• You will be given a general anaesthetic, so you will be completely asleep and won't feel or remember anything
• Mr Nguyen makes a small incision to the side of your anal canal — not at the fissure itself
• He carefully identifies the internal sphincter muscle and divides a precise, measured portion of it — only as much as is needed
• The wound is closed with a dissolving suture — there are no stitches to remove later
• Local anaesthetic is injected into the area before you wake up, so you come around as comfortable as possible
• You will rest in the day-stay unit for 1 to 2 hours, then go home with pain relief and stool softeners, and written instructions to guide you through the first week

Recovery & aftercare

• Day 0 to 1: Some mild to moderate soreness around the wound is normal. Paracetamol works well, and warm sitz baths — sitting in a few centimetres of warm water for 10 to 15 minutes — are genuinely soothing.
• Days 2 to 5: This is when most people notice a real and welcome shift. The deep, searing fissure pain that made every bowel movement feel like an ordeal often improves dramatically within the first few days — sometimes faster than people expect.
• Days 5 to 7: Most people feel well enough to return to light work and normal daily activities.
• 3 to 4 weeks: You can gradually return to all activities, including exercise. The fissure should be fully or nearly fully healed by this point.
• Keep your diet high in fibre — fruit, vegetables, wholegrains — and drink plenty of water long-term. This is the most important thing you can do to keep your stools soft and prevent the fissure from returning.
• Please call us if you develop a fever, if your pain is getting worse rather than better, or if you notice the wound opening up. We would rather hear from you early.
• Mr Nguyen will see you for a routine follow-up appointment 2 to 6 weeks after your procedure. This review is provided at no charge.

Related patient guides

Plain-English articles written for patients and their families — good reading at any point before or after your appointment, at whatever pace suits you.