Lateral internal sphincterotomy

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.

A carefully measured, limited sphincterotomy is performed — dividing only the proportion of the muscle that's needed to relieve the spasm. Keeping the division limited is the standard technique for reducing the risk of any change in continence. The whole operation is done under a general anaesthetic, and you go home the same day.

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

• A well-established healing rate — in published series, around 90 to 95 in every 100 fissures heal within a year
• A single day procedure under general anaesthetic — you go home the same day
• Most people notice their fissure pain starting to ease within the first few days after surgery
• Durable healing in most cases — the published recurrence rate is under 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

Going into this procedure with a clear picture of the risks matters. The most important one to understand is the possibility of a change in bowel control, and what follows is an honest but reassuring explanation of what that actually means in practice.

• Difficulty controlling wind (passing flatus) — in published series, this happens in around 5 to 20 in every 100 people. For most people, it is minor and temporary — settling within a few months as the muscle adjusts to the change. Permanent, more bothersome difficulty is uncommon (in published series, around 3 to 10 in every 100 people).
• Difficulty controlling liquid stool — this affects fewer than 5 in every 100 people, and is usually temporary. Limiting the depth of the muscle division is the standard technique used to reduce this risk.
• 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 rare complication.

Please raise any questions or concerns about these risks at consultation — all of them can be discussed in as much detail as you need, and there is no such thing as a question too small.

If you take blood thinners, diabetes medication, GLP-1 weight-loss injectables, or iron supplements, please flag this when you book — these need specific adjustments before the procedure. Full details are in the guide above.

• 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, the benefits, risks (including the continence risk explained above), and what to expect are discussed at consultation. Please bring any questions — there will be time to answer them
• You can continue using any prescription cream or ointment right up until the day of your operation

• You will be admitted to the day-surgery unit at Warringal Private Hospital or Epworth Eastern on the morning of your procedure and given a general anaesthetic, so you will be completely asleep and won't feel or remember anything
• A small incision is made to the side of your anal canal — not at the fissure itself
• The internal sphincter muscle is carefully identified and a precise, measured portion is divided — 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

• 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 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 motion feel like an ordeal often improves 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.
• A post-procedure review is routinely arranged 2 to 6 weeks after your procedure — this review is provided at no charge.
• For day-by-day guidance on stool softening, sitz baths, wound care, and what to expect during healing, see the Post-anal-fissure aftercare guide on the Resources page.

Post-operative concerns: Please call our rooms on (03) 9816 3951 and leave a message — this will be sent directly as a text to Mr Nguyen. Alternatively, you may text the office mobile on 0499 090 126. We aim to respond promptly during business hours.

Emergencies: For any life-threatening emergency, call 000 immediately or go to your nearest emergency department. Do not wait for a call back from our rooms. For the Austin Hospital Emergency Department: (03) 9496 5000.