Lateral Internal Sphincterotomy

A lateral internal sphincterotomy is a surgical incision into one of your anal sphincter muscles. It’s a treatment for anal fissures that have failed to heal. Cutting the muscle helps release excess tension that may be preventing the wound from healing. The surgery has a high success rate and a low rate of complications.


What is a lateral internal sphincterotomy?

A lateral internal sphincterotomy is a surgical operation on your internal anal sphincter, the ring of smooth muscle that surrounds your anal canal. A sphincterotomy is a type of myotomy, which means your surgeon makes a small cut into the muscle to relieve excess tension. They do this when excess tension in the muscle is causing complications.


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What does a lateral internal sphincterotomy treat?

Most people have a lateral internal sphincterotomy to treat a chronic anal fissure. An anal fissure is a painful tear in the lining of your anal canal. It becomes chronic when it fails to heal after at least eight weeks. Most anal fissures heal easily. When they don’t, it’s because excess tension in the internal sphincter muscle is preventing them from healing.

Why do you need a lateral internal sphincterotomy?

When an anal fissure exposes the muscle underneath the anal lining, it can trigger uncontrollable spasms. Spasms pull the wound apart and reduce blood flow, preventing it from healing. Pain, especially with pooping, increases the tension and spasms. Eventually, the muscle begins to bulk up from the exercise, which widens the fissure.


How common is this procedure?

Most anal fissures won’t need surgery, but studies suggest that up to 40% of fissures may resist healing and become chronic. Healthcare providers recommend surgery when it appears your fissure won’t heal without it. Lateral internal sphincterotomy (LIS) is the most common surgery they recommend. It has a high success rate and low rate of complications.

Procedure Details

How should I prepare for a lateral internal sphincterotomy?

Lateral internal sphincterotomy is an outpatient procedure, meaning you can go home the same day. But you’ll have to arrange for someone else to drive you. The anesthesia you have during surgery will make it unsafe for you to drive. Most people have general anesthesia, though you can discuss other options with your provider. They’ll all affect your driving.


What happens during a lateral internal sphincterotomy?

During this operation, your surgeon will make a small lateral incision into your internal anal sphincter. (Lateral means coming from the side.)

You have two anal sphincter muscles that surround your anal canal and help control your bowel movements. The internal sphincter is the inner ring, while the external sphincter surrounds it. The external one is under your control, but the internal one is involuntary. This one stays contracted as a default, and only relaxes during bowel movements.

Your surgeon will cut into the muscle directly under your anal fissure to release tension. The aim is to reduce the constant pressure by 20% to 50%. This should prevent spasms and improve blood flow, enabling your fissure to heal. They’ll locate the anal fissure using an anoscope (speculum), then use a scalpel or electrocautery to cut the muscle beneath.

The procedure itself takes about 30 minutes. The whole appointment might be two to three hours.

What should I expect after a lateral internal sphincterotomy?

When you go home, you can expect:

  • Some postoperative pain for a few days. You should be able to manage it with medications.
  • Some anal discharge for a few days, including fluids and a small amount of bleeding.
  • Some delay before your first bowel movement. Surgery and anesthesia can cause constipation.
  • To take it easy for the next week or two, though the pain should go away sooner.

How painful is a sphincterotomy?

Under anesthesia, you won’t feel pain during the procedure. Your surgeon can also apply an additional local anesthetic to the operative site during your procedure to help prevent pain after the other anesthesia wears off. They’ll give you a prescription for pain relievers to use over the next few days. Most people say they don’t need them longer than that.

How do you poop after a sphincterotomy?

You may have some pain with pooping after your surgery. If you’ve been living with a chronic anal fissure, this won’t be anything new to you. You may already know some tricks for making bowel movements easier. What will be new is that your fissure will finally be on the mend, and you’ll have pain medications to ease your recovery. You can also:

  • Apply a topical ointment to your wound before you poop.
  • Use stool softeners to make passing poops gentler.
  • Use a step stool to prop up your feet while you poop, which positions your hips better.
  • Use baby wipes instead of toilet paper to wipe.
  • Use a bidet or shower head to rinse your wound after pooping.
  • Soak your anus (butthole) in a sitz bath after pooping.

Risks / Benefits

What are the benefits of sphincterotomy?

When anal fissures don’t heal, they cause constant pain, especially with bowel movements. This not only affects your quality of life but also raises your risk of infections and other complications. Surgery can offer definitive relief. Lateral internal sphincterotomy is the oldest surgical procedure for chronic anal fissures, and it has a 95% success rate in curing them.

What are the possible risks or complications of this procedure?

Any surgery comes with a small risk of certain complications, like bleeding, infection and reactions to the anesthesia. These are rare. Sphincterotomy, in particular, can cause certain short-term complications in up to 50% of people. They usually go away when you’ve recovered. Long-term complications of sphincterotomy are rare: most estimates are less than 5%.

Possible complications include:

  • Leakage. You might experience minor fecal incontinence, like leaking small amounts of poop or gas during your recovery. This is short-term for most people, but may last longer for a few.
  • Difficulty peeing. Some people experience short-term urinary retention after surgery — difficulty letting pee come out. It usually gets better on its own, but contact your provider anyway.
  • Recurrence. It’s possible for a fissure to come back even after surgery, though this is rare. It might happen if it didn’t heal properly, or if there’s another underlying condition involved.

Recovery and Outlook

How long does it take for a lateral internal sphincterotomy to heal?

It takes about six weeks for your anus to heal completely. Any short-term complications should also resolve within this time. But you’ll begin to feel better much sooner. Most people say the pain only lasts a few days. Most people return to their normal activities after a week or two, depending on how strenuous those activities are. Your provider will advise you.

When To Call the Doctor

When should I call my healthcare provider?

Contact your provider if you have complications during your recovery, like:

  • Signs of infection, like a fever, redness or swelling.
  • Excessive rectal bleeding or foul discharge, like pus.
  • Excessive anal pain that you can’t relieve with medications.
  • Urinary retention (difficulty peeing).

Additional Common Questions

What is a fissurectomy vs. sphincterotomy?

A fissurectomy is a newer, alternative surgery for a chronic anal fissure that doesn’t involve cutting the sphincter muscle. Instead, a surgeon cuts out the surface layer of the wound, which may have developed scar tissue from chronic healing and reopening. They also remove other skin complications, like skin tags or piles, to help the wound heal.

Surgeons usually combine a fissurectomy with a Botox® injection into the sphincter muscle to help it relax. The injection lasts for a few months, long enough to allow the fissure to heal. Some surgeons feel this is a safer alternative for people who may be more prone to incontinence. Since Botox is temporary, it shouldn’t have long-term effects on your muscle.

Which surgery is better for me?

Lateral internal sphincterotomy is generally considered the gold standard in surgery for anal fissures, because of its solid history and 95% success rate. Long-term incontinence after LIS is rare and usually minimal. But some people may be more at risk of long-term incontinence than others. In these cases, some surgeons might recommend fissurectomy instead.

A note from Cleveland Clinic

If you have an anal fissure that hasn’t healed for eight weeks or more, you’ve already been through a lot. It can be daunting to consider having surgery on top of it all. But surgery will bring the relief you need. Even right after your sphincterotomy, your pain levels are likely to be better than before. And after a few days of healing, you’ll start to feel much better.

Medically Reviewed

Last reviewed on 01/10/2024.

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