Anal Stenosis or Stricture: Causes, Symptoms, Diagnosis, and Treatment

anal stenosisAnal stenosis can be a serious health concern that may have a significant impact on a person’s overall well-being. Understanding the causes and signs of anal stenosis and receiving early treatment can help people avoid complications.

Also referred to as anal stricture or rectal stricture, anal stenosis is a narrowing of the anal canal that makes it very hard to pass stool. It happens when the muscles of the anus, which normally expand and contract to assist passage of stools, suddenly become narrow.


The anal canal is located just before the anal sphincter. The anal sphincter is a part of the body that holds a seal that opens to discharge waste from the body. There are two anal sphincter muscles, internal and external. The internal sphincter is what we call an involuntary muscle. In other words, you can’t control it.

The external sphincter is wrapped around the internal sphincter muscle. This is the muscle that we squeeze when we feel the urge to go to the bathroom but aren’t anywhere near a toilet. It is a voluntary muscle; a muscle we do have control over.

What Are the Causes and Symptoms of Anal Stenosis?

We have addressed the question, what is anal stenosis? Now, it is important to get a sense of how someone gets this condition. There are several anal stenosis causes, including those listed here:

  • Spasm: An internal sphincter spasm can happen if a person experiences anal fissures. Rectal stenosis associated with this type of spasm can be painful and require a surgical procedure called lateral internal sphincterotomy.
  • Postoperative Scarring: This is the most common cause of anal stenosis. Any incisions made in the anal canal can produce circular scarring. For instance, this can occur due to the surgical removal of hemorrhoids.
  • Chronic Diarrhea: If someone has constant diarrhea, then the anus never stretches the way it’s supposed to. Over time, the anus will lose its ability to dilate. Individuals who suffer from inflammatory bowel diseases such as Crohn’s disease or ulcerative colitis have a higher risk of this happening.
  • Age: It is not unusual for anal canal stenosis to occur in elderly people who are senile or suffer from Alzheimer’s disease, especially if they take too many laxatives. In these people, both anal stenosis and atrophy may be playing a role in the lack of natural dilation.
  • Sepsis: This is a severe blood infection that can jeopardize organs.
  • Parasites: An infection caused by the amoeba Entamoeba histolytica can lead to anal stenosis. This parasite tends to be more common in developing countries where barriers between human feces and water supplies are inadequate.

Other possible causes include congenital deformity, rectal infection, rectal trauma, intestinal malabsorption, weak blood vessels, radiation therapy, and venereal disease.

Anal stenosis symptoms vary slightly from one person to another, but generally, constipation will occur since it’s difficult to pass stool. Anal stricture symptoms can also include the following:

Also read: Bowel movements: How often should you poop?

How Is Anal Stenosis Diagnosed?

Anal stenosis can be diagnosed as mild, moderate, or severe. Insertion of an anal dilator is possible with mild or even moderate cases but is not in severe situations. In all cases, a physical examination confirms the diagnosis, although the doctor will pay particular attention to any symptoms the patient describes, including constipation, abdominal pain, and bloody stools.

The examination will include a visual review of the anal canal and surrounding skin, as well as a digital rectal test. There are some situations where it’s too painful for the patient to go through an examination of the anal canal, so anesthesia will be used.

Some doctors may choose to do an anorectal manometry, which is a test that measures the pressures of the anal sphincter muscles, the sensation of the rectum, as well as reflexes that are used for normal bowel movements. During the test, a small balloon attached to a catheter-like tool may be inflated in the rectum and a machine connected at the other end of the catheter produces the measurements.

Treatment Methods for Anal Stenosis

Anal stenosis treatment is usually based on the cause and severity of the condition. The following covers the most common treatment methods, including non-operative management.

  • Dietary Adjustments: This is for mild anal stenosis and can include eating foods with more fiber, which can make stools larger.
  • Stool Softeners: For mild to moderate anal stenosis, this can help stretch a mild stricture.
  • Anal Dilation: This is a way to stretch the anal canal. It involves placing your index finger into the anus two times a day for about two months to help stretch the area. In severe situations, this can be done at a hospital.
  • Steroid Injection: When injections are made right into a scar it can potentially reduce recurrence of stricture.
  • Botox: Injections of Botox have been known to help stenosis caused by spasm.
  • Surgery: Two surgical options are sphincterotomy, which is used to repair fissures, or angioplasty, which is a flap procedure whereby healthy tissue is used replace a defective area after scar tissue has been removed.


A lot of people experience constipation and fissures from time-to-time but it doesn’t mean they have anal stenosis. If you ever have a hard time passing stool, are in pain, or see blood in your stool or on your toilet paper, you should seek medical attention.

In the majority of cases, complications such as infection and bowel disease are ruled out and the doctor is able to identify the cause. Once a cause is determined, the doctor can guide you to treatment that will protect not only your bowel, but also your overall health.



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