Lateral Internal Sphincterotomy: What to Know

Medically Reviewed by Minesh Khatri, MD on May 27, 2023
3 min read

A bowel movement can be an effective way to gauge whether you're in good health. The foods you eat, the amount of exercise you get, and how much water you drink affect your digestive system and poop. If you're experiencing severe pain while going to the bathroom or notice any blood in your stool, it may be a sign of an anal fissure.

Anal fissures, or tears, are common and often heal with treatment. Sometimes, the wound won't heal or gets worse. That's when surgery may be necessary.  

A lateral internal sphincterotomy is a surgery that repairs an anal fissure. It helps reduce pressure inside the anus that can cause spasms and increases blood flow to the area to help the tissue heal.


Anal fissures result from dry, hard stool or a series of loose bowel movements that tear the inner lining of your anus. Some people have tighter sphincter muscles, putting them at a higher risk of developing anal fissures. Other causes including inflammatory bowel disease, trauma, anal infections, and tumors. They're often confused with other anal conditions, like hemorrhoids. 


An anal fissure causes sharp pains during a bowel movement. This pain can last from 15 minutes to several hours. Other signs and symptoms include: 

  • Bloody stool or blood on toilet paper after you've had a bowel movement
  • A painful — and often visible — crack in the skin surrounding your anus
  • Lumps or skin tags on the surface near the anal fissure

If you have any of these symptoms or have a history of anal fissures, talk to your doctor.

Once you've experienced a tear, it can lead to a repeated injury called a chronic anal fissure. It's the result of muscle spasms in your sphincter. Spasms are not only painful but can pull the unhealed fissure apart, making the wound worse. These spasms can cause even more tearing when you use the bathroom.  

Talk to your doctor if you experience these complications from an anal fissure: 

  • Constant bleeding (you'll likely see the blood on toilet paper after you wipe)
  • Pain or discomfort
  • Trouble passing stool 
  • Clotting
  • Inability to control gas or bowel movements
  • Reduced quality of life 

If other medical treatments, diet, or lifestyle changes aren't working, surgery may be the best option. 

A lateral internal sphincterotomy is a short surgery, lasting an average of 30 minutes. Most of the time, you'll return home the same day.

You can be asleep or awake during surgery. If you're awake, the surgeon will likely give you medicine to ensure you're relaxed. During the procedure, the surgeon will place a scope, or lighted tube, into your anus to get a better view of your injury. Small medical tools are used to cut the internal anal sphincter, which is the small ring of muscle that controls your anus.

After Surgery 

For most patients, the pain will go away within the first few days to a week after the surgery. You'll be able to participate in your usual activities and work within a week or two. It can take up to six weeks for the wound to fully heal.

Here are some ways to take care of yourself after the procedure: 

  • ‌Get plenty of rest
  • Take short walks each day to prevent constipation and increase blood flow
  • Drink plenty of fluids and eat fiber to prevent pain when you use the bathroom  
  • Place a small stool under your feet when you sit on the toilet to place your body in a squatting position
  • Take several short sitz baths throughout the day to encourage healing
  • Use baby wipes or medicated wipes to clean the area instead of toilet paper, which can be irritating 

It may still be painful to poop for the first few days, but it's typically less than the pain you felt before the surgery. You may notice small amounts of blood on your toilet paper for the first few weeks. This is normal. It can take up to six weeks for the wound to fully heal.

The most common complication after surgery is anal incontinence. Around half of patients experience this after surgery, but for most, it resolves over time. This can show up as the loss of stool or the inability to control your gas. Other minor complications include: 

  • Infection
  • Excessive bleeding
  • Fistula