Anal Rectal Motility
In anorectal manometry, a thin tube, called a manometry probe, is inserted into the anal canal and slowly withdrawn. The probe is attached to a pressure transducer that measures the pressures exerted by the rectal and anal sphincter muscles, which relax and contract to control bowel movements.
An alternative method uses another type of probea metal cylinder equipped with three balloons (known as a three-balloon manometry system)to measure the anal and rectal sphincter pressures.
Purpose of the Anorectal Manometry
- To evaluate functioning in the anal canal and determine the cause of chronic constipation or fecal incontinence
- To confirm the diagnosis of Hirschsprung’s disease (a defect in the nerves of the colon that causes chronic constipation)
- Sometimes, this procedure is used as a treatment to retrain anal muscle contraction in people who experience fecal incontinence.
Who Performs Anorectal Manometry
- An experienced gastroenterologist or a specially trained assistant
Special Concerns about Anorectal Manometry
- Anorectal manometry is not necessary for many cases of fecal incontinence. It is performed only in carefully selected patients, including those with suspected anorectal muscle or nerve damage caused by surgical trauma or systemic disease (such as diabetes or scleroderma) and those suspected of having Hirschsprung’s disease.
- This test should not be performed in individuals with active lower gastrointestinal (GI) bleeding.
- The test is not possible in people who are allergic to latex or rubber.
- Anorectal manometry may be done in a hospital procedure room or in a doctor’s office.
Before the Anorectal Manometry
- You must not eat or drink anything for four hours before the test.
- If you have any medical problems, particularly allergies, tell the doctors about it.
- You may be given a cleansing enema to clear the rectum.
- If you are very anxious prior to the test, the doctor may administer a sedative.
- You will be asked to disrobe and put on a hospital gown.
What You Experience
- You will lie down on an examining table.
- The examiner inserts a gloved, lubricated finger into your rectum to perform a manual examination.
- The manometry probea narrow tube of soft plastic or rigid metalis gently inserted about four inches into the rectum.
- As the manometer is slowly withdrawn, it measures the pressure exerted by the rectal and anal muscles. This procedure may be repeated several times to confirm the results.
- Next, a balloon at the tip of the probe is inflated slowly, and you are asked to tell the doctor when you experience the sensation of rectal fullness and the urge to defecate.
- Pressure may also be measured as you squeeze the anus as hard as possible.
- Alternatively, three-balloon manometry uses another type of probea hollow, metal cylinder equipped with three special manometry balloons. When the probe is positioned in the rectum, the balloons are inflated and the pressure readings are noted. You will be asked to tell the doctor when you experience the sensation of rectal fullness and the urge to defecate.
- The probe is withdrawn.
- The procedure takes up to 45 minutes.
Risks and Complications of Anorectal Manometry
- Anorectal manometry is considered a safe procedure, but you will experience some discomfort as the probe is inserted and removed.
After the Anorectal Manometry
- Most patients may return home immediately and resume their usual activities.
Anorectal Manometry Results
- Your doctor will review the test findings.
- In general, high pressures in the anal canal may cause constipation, while low pressures may lead to fecal incontinence. Analysis of muscle and nerve function at different points along the length of the anal canal may indicate specific conditions, such as Hirschsprung’s disease.
- Based on the test findings, your doctor should be able to recommend an appropriate course of treatment, depending on the specific problem.
The Johns Hopkins Consumer Guide to Medical Tests
Simeon Margolis, M.D., Ph.D., Medical Editor
Updated by Remedy Health Media