Anorectal Manometry Procedure

What is Anorectal Manometry?

Anorectal manometry (AKA anal manometry) is a diagnostic procedure that evaluates the function and strength of the muscles and nerves in the rectum and anus.

Specifically, the procedure measures the pressures related to the movement of waste through the anal canal and rectum, the force exerted by the rectal and anal muscles, sensation in the rectum and the neural reflexes involved in having a bowel movement. The procedure is primarily used to help evaluate patients with issues like fecal incontinence, chronic constipation and other issues involving the function of the anus and rectum.

The test utilizes a small, flexible tube with a small balloon attached, which is inserted into the rectum and may be filled with water or air during the procedure to help simulate a bowel movement. The tube is connected to a machine that measures the pressure exerted by the muscles in the anal canal and rectum as they contract and relax.

The goal of anorectal manometry is to determine if the rectum and anal sphincter muscles are working well enough to ensure proper bowel movements, assessing if these specialized muscles contract and relax as they should.

What is Anorectal Manometry Used to Diagnose?

Anorectal manometry serves as an important diagnostic tool for several conditions, including:

  • Fecal incontinence: Fecal incontinence occurs when patients can’t control their bowel movements, leading to the unintentional release of stool. The test can help physicians treat fecal incontinence by measuring the strength and tone of the anal sphincter and the sensitivity of the nerves that control the muscles of the anus and rectum. This can help determine if nerve issues or weak anal sphincter muscles are contributing to the inability to control a bowel movement or if the anal sphincter muscle tightens as it should.
  • Chronic or severe constipation: Individuals with severe constipation have difficulty passing stool and may experience symptoms like painful, hard or infrequent bowel movements. Anorectal manometry can help pinpoint the cause of a patient’s constipation and suggest treatments that can help them have more normal bowel movements.
  • Hirschsprung disease: Hirschsprung Disease is a birth defect of the large intestine in which certain nerve cells don’t form properly. That can cause an inability to move stool through the digestive system, which can result in blockage. According to the National Institutes of Health, about 1 in 5,000 newborns has Hirschsprung disease. Anorectal manometry can diagnose Hirschsprung’s disease by assessing the pressure of the anal sphincter muscles and checking for the presence of abnormal reflex pathways.

How is Anorectal Manometry Performed?

During the procedure, the patient is usually placed on their left side in a fetal position. A nurse or technician will then lubricate the patient’s rectum and insert a small, flexible tube with a balloon attached.

The tube is connected to a medical device that measures the pressures exerted by the rectum and anus. The small balloon at the tip of the catheter may be inflated with water or air during the test to evaluate normal reflex pathways and muscle response.

During the procedure, the patient may be asked to let their anal sphincter muscles relax, to relax the muscles of their lower abdomen, or to squeeze or push at different times to measure the pressures during these actions.

The patient may also be asked to perform what’s called a balloon expulsion test, which is meant to simulate and measure how the rectum and anal sphincter muscles tighten and relax while a patient defecates.

During the test, the balloon that was inserted into the rectum is inflated with a small amount of water or air. The patient is then asked to try to expel the balloon from the body.

As this occurs, the time it takes for the patient to expel the balloon is carefully recorded. Prolonged balloon expulsion could suggest there’s a physical issue with the nerves or muscles in the rectum or lower digestive tract.

What Do I Need To Do To Prepare for the Anorectal Manometry Procedure?

Preparation for anorectal manometry involves ensuring that the bowels are empty. This can be achieved by taking a laxative or an enema. Patients should also avoid eating or drinking for at least two hours before the procedure.

Before the test, patients might be asked to change into a hospital gown and provide a brief health history. It’s important to inform the doctor before the procedure about any medications you’re taking, as some can affect the results. Any allergies you should also be communicated to the doctor.

Does Anorectal Manometry Require Sedation?

No, anorectal manometry does not typically require sedation. The patient remains awake and alert throughout the procedure. While some discomfort might be felt during the insertion of the tube into the rectum, the procedure is generally not painful.

Is Anorectal Manometry an Outpatient Procedure?

Yes, anorectal manometry is an outpatient procedure. This means that unless they are hospitalized, patients can go home on the same day after the test. There’s no need for an overnight hospital stay.

Which Patients Aren’t Right for the Anorectal Manometry Test?

While anorectal manometry is generally considered a safe and low risk procedure, there are certain conditions where it might not be recommended. These include patients with:

  • Acute anal or rectal pain
  • Recent surgery in the anal or rectal area
  • Large hemorrhoids
  • Anal fissures, which are tears that can develop in the lining of the anus

If you are experiencing any of these issues, be sure to talk to your doctor before undergoing the test.

Is Anorectal Manometry Painful or Uncomfortable?

While the anorectal manometry procedure is generally considered safe and causes minimal discomfort, some patients might experience an uncomfortable sensation or slight pain due as the tube is inserted into the rectum. The pressure exerted by the anal sphincter muscles during the test can also cause some discomfort. However, serious complications are rare.

When Can I Expect My Anorectal Manometry Results?

The test itself should take less than an hour. After the procedure, patients can usually resume their normal activities. Full interpretation of the data requires a comprehensive review by technicians and specialists, so it might be several days before you receive your test results.