Overview of Internal Anal Sphincterotomy
An anal fissure is a common, non-cancerous condition that can affect both children and adults. Essentially, it’s a small cut or tear in the lining of the anus, the opening where stool passes out of the body. The cause is often a hard, large bowel movement. This condition can often lead to recurring pain and bleeding during bowel movements, which can progress to long-term (chronic) anal fissures in up to 40% of those affected.
Usually, doctors can identify an anal fissure based on the symptoms you describe. Symptoms may include moderate to severe pain during bowel movements, and variable amounts of bleeding. The bleeding typically appears as blood on toilet paper during wiping. The pain usually lasts for about 15 to 30 minutes after a bowel movement. If the tear exposes the internal muscle ring (sphincter) at the end of the anus, it may painfully contract, making the situation worse. If undealt with, the muscle may grow bigger, leading to unhealing fissures.
Generally, fissures heal on their own in children, but in adults, they might require surgical treatment.
Most anal fissures (90%) are found in the posterior midline, the back easily accessible part of the anus. However, in about 25% of females and 8% of males, they can be found in front, another easily accessible part of the anus. Fissures located at the sides of the anal opening may raise concerns about other conditions like inflammatory bowel disease or granulomatous diseases, which are long-term conditions causing inflammation of the intestine.
For early-stage fissures, several medical treatments such as ointments, dietary fiber, and topical nitroglycerin, a medicine that helps to relax and widen blood vessels, can help in the healing. Surgical options include botox injections, removing the fissure, or various operations and interventions to the anal sphincter, the muscle controlling the release of stool.
A specific type of surgery, known as ‘internal lateral anal sphincterotomy’, has been around since 1951 and is often used. It involves making a small cut in the anal sphincter muscle to reduce pressure in the anal canal, which brings quick symptom relief. This highly effective procedure (with around a 95% success rate after 3 weeks) is considered the most effective surgical treatment for anal fissures.
Anatomy and Physiology of Internal Anal Sphincterotomy
The anal canal is a small passage in our body that can be described in two different ways: functionally (from a surgical perspective) and anatomically. When looking at it from the surgical perspective, the anal canal is roughly 4 cm long and stretches from the anal verge (the boundary between the outside of the body and the anus) to the anorectal ring or puborectalis sling (a kind of muscle ring inside the anal canal). From an anatomical perspective, the canal is 2 cm long and extends from the anal verge to a point called the dentate line.
The anal canal is made up of two muscle structures, both of which help us control our stools. The first muscle structure, called the internal anal sphincter, is the inner layer of the anal canal and is made up of smooth muscle. It is around 2.5 to 4 cm long and 2 to 3 mm thick. This muscle is involuntary, which means it operates without us having to consciously control it. Under normal circumstances, it stays contracted, preventing us from losing control of our stools. When we need to pass stool, it relaxes allowing bowel movements to occur.
The second muscle, the external anal sphincter, is the outer layer of the anal canal and made up of striated muscle. It is a muscle tube that sits around the anal canal and connects with other muscles such as the puborectalis and the levator ani muscles. Unlike the first muscle, we can voluntarily control this muscle, it helps us regulate the process during bowel movements.
Why do People Need Internal Anal Sphincterotomy
If you have tried conservative medical treatments for 6 weeks to 3 months without seeing improvements, your doctor may suggest a procedure called an internal anal sphincterotomy. This is a surgery that might help improve your condition. A vital thing to keep in mind is that you should have good control over your bowel movements before undergoing this operation. This is important because it can help lower the risk of not being able to control bowel movements after the surgery.
When a Person Should Avoid Internal Anal Sphincterotomy
Those who have difficulty controlling their bowel movements usually can’t undergo this procedure. Furthermore, if the fissure, or tear, is in an unusual location, a thorough check for other diseases needs to happen before considering surgery.
Equipment used for Internal Anal Sphincterotomy
It’s important that there are different sizes of tools called anoscopes handy. An anoscope is a tube-like instrument that doctors use to view the anus and lower rectum. Also, there should be a device known as an electrocautery surgical unit. This device uses electric current to seal wounds or cut body tissue.
A tool called the Hill-Ferguson anal retractor, which also comes in various sizes, should be available. This is used to keep the anus open during medical procedures.
Depending on what the surgeon prefers, they may use a bovie-electrocautery device or an 11-blade scalpel. A bovie-electrocautery device is similar to the electrocautery surgical unit mentioned earlier, while an 11-blade scalpel is a sharp tool used for surgical cutting.
In addition, a minor set should be opened. This is a set that contains a variety of smaller instruments that might be used during the procedure.
Who is needed to perform Internal Anal Sphincterotomy?
For the surgery, not only the surgeon is needed, but also an anesthesiologist, a nurse who specializes in anesthesia, and a surgical scrub technician, a specialist who ensures a sterile field in the operating room. These individuals work as a team during the operation. However, if the surgical procedure is performed in a doctor’s office, the team may be smaller, usually just the surgeon and an assistant. These medical professionals have the skills necessary to ensure your care and safety throughout the procedure.
Preparing for Internal Anal Sphincterotomy
For a surgical procedure like a sphincterotomy, which is a treatment for anal fissures, you don’t need any special preparation like cleaning out your bowels beforehand. The area that will be operated on is usually cleaned with an antiseptic solution. This solution is used to remove germs and reduce the risk of infection.
Regarding antibiotics, in most instances, you won’t need to take any antibiotics before this procedure.
The surgery can be done either in a doctor’s office using a local anesthetic — meaning you’ll be awake, but the area being operated on is numbed — or in an operating room using regional or general anesthesia, which can make you feel drowsy or unconscious. The choice of whether to use local, regional, or general anesthesia depends largely on what you and the surgeon decide. However, it’s important to know that studies have shown a higher chance of the anal fissure coming back if the surgery is done with only a local anesthetic.
Your position during the surgery can vary. You might be placed in a prone jackknife position, which means lying on your stomach with your hips bent and legs hanging off the side of the table; a lithotomy position, which means lying on your back with your legs raised and spread apart; or a lateral decubitus position, which means lying on your side. The choice of position depends largely on the surgeon’s preference, your body shape, and your health condition. If you are significantly overweight, you may not be able to tolerate the jackknife and lithotomy positions. Generally, the surgeon prefers using the lithotomy position.
How is Internal Anal Sphincterotomy performed
The doctor prepares the patient for surgery in a usual manner ensuring the patient’s cleanliness and the sanitary condition of the surrounding area. A specialized retractor tool or a tube called an anoscope is used to examine the anal canal to check for any diseases or problems. This procedure helps the doctor figure out the exact location of an anal fissure. An anal fissure refers to a small tear in the lining of the anus which can cause pain and bleeding while passing stools. It’s often associated with an inflamed hemorrhoidal complex which is a blood vessel complex found in the lower rectum and anus. Both structures can be removed, and the tissues lining the anus are then stitched together using a dissolvable suture. The details of how the doctor proceeds depends on the surgeon’s judgement.
Open Procedure:
In this surgery, a small cut is made over the area between the internal and external anal sphincter muscles. For context, sphincter muscles control the opening and closing of the anus. The cut exposes the internal sphincter muscle, which is then separated from the external one using a haemostat or similar tool and then the muscle is cut till it reaches the level of the dentate line, which is a line inside your anal canal using a technique called electrocautery (a method to remove or cut tissues using heat) or by using a surgical knife. If the cutting is done by a surgical knife, the doctor ensures there is no bleeding to prevent complications after surgery. Then, the skin is left alone to heal by itself, or it can be stitched up using a dissolvable sutures.
Closed Procedure:
In this technique, the doctor uses their finger to feel the area between the internal and external anal sphincter muscles in the lower side of the patient’s body. Then, a surgical knife is inserted into this area while taking care to do this under the dentate line. The knife is then moved towards the middle dividing the internal sphincter. The cut is left open to allow it to heal naturally.
Possible Complications of Internal Anal Sphincterotomy
Having surgery on the internal anal sphincter can lead to difficulty controlling bowel movements, otherwise known as anal incontinence. This means you might struggle to control the release of gas or even stool, which can be messy. However, this problem shouldn’t last long and is generally resolved in most people.
In a large analysis of other studies, 4512 patients were tracked. They had a specific type of surgery, called a lateral internal sphincterotomy, for a chronic anal fissure, which is a tear or cut in the skin of the anal canal. Two years after the surgery, it was found that about 14% of these patients had some trouble with bowel control. However, only less than 2% had severe incontinence where they involuntarily lost feces.
Some experts suggest limiting the extent of the surgery according to the length of the fissure to decrease the risk of incontinence. However, this can increase the chance of the fissure either not healing completely or coming back.
Other less serious complications of this surgery can include infection, bleeding, and the creation of an abnormal connection or tunnel, known as a fistula, between two parts of the body.
What Else Should I Know About Internal Anal Sphincterotomy?
Anal fissures, or small tears in the skin around the anus, are a common source of discomfort, impacting an estimated 250,000 new people each year in the U.S. alone. However, it’s hard to know the exact number of people with anal fissures. This is because many people might feel awkward talking about problems in the rectal area. Men and women are equally likely to get anal fissures.
It’s more common for anal fissures to come back if you’ve only had medication to treat them. On the other hand, it’s rare for them to come back if you’ve had surgery to treat them. If surgery doesn’t help and the problem keeps coming back, doctors might need to look for other possible causes.
