Ask the doctors: Bowel issues evaluated through tube testing

Dear Doctors: I have been having some problems with voiding my bowels, and my doctor has started talking about GI motility. Can you explain what that is? She also wants me to have something called anorectal manometry testing. I would like to know more about that, too.

Dear Reader: Your symptoms have alerted your doctor to potential issues with gastrointestinal motility, which is often shortened to GI motility.

The term refers to the body's ability to move liquids and solids throughout the length of the gastrointestinal tract.

GI motility entails a coordinated series of wavelike motions. Unless something goes awry with the muscles, structures and signaling it involves, it's a process we rarely notice.

Yet, the journey itself, along with the tissues involved, is complex. It begins in the throat, also known as the pharynx, and moves on to the esophagus, stomach and small and large intestines.

The ingested liquids and solids that remain after digestion and absorption complete the journey in the rectum and anus. That's where the final step of GI motility takes place. Working together, the nerves and muscles of the rectum and anus produce a bowel movement.

In certain cases, symptoms such as ongoing constipation or diarrhea can indicate a problem with GI motility. Additional symptoms can include heartburn, indigestion, nausea, difficulty swallowing and vomiting. Because each of these are common to a wide range of conditions, disorders and diseases, tests can be needed to narrow down and pinpoint a cause.

Among these tests is the one you have asked about, anorectal manometry. It is used when GI motility in the terminal end of the lower GI tract needs to be evaluated.

The results provide information about the functioning of the anorectal sphincter muscles, which are involved in the control of bowel movements.

This includes measuring pressure exerted by the anal sphincter muscles and the sensations that are present in the rectum. The test also evaluates the neural connections and reflexes that are required for the bowels to function properly.

Anorectal manometry involves the use of a flexible, pressure-sensitive tube, about the length and width of an old-fashioned thermometer. It is tipped with a tiny, inflatable balloon.

The patient lies on their side on an examination table, and the instrument, which is lubricated, is guided into the rectum. It can be uncomfortable, but it is usually not painful. During the test, the doctor asks the person to squeeze, relax and bear down with their rectal muscles.

In another part of the test, the tiny balloon is inflated with air.

The way in which the body responds provides important information about the reflex pathways in the rectum. In the final part of the test, the balloon is filled with water. The patient is asked to engage their rectal muscles to expel the balloon, as they would when having a bowel movement.

Taken together, the various parts of the test provide a detailed profile of rectal and anal function. The information helps to narrow down potential causes of symptoms associated with bowel control, which are common to a number of conditions.

Eve Glazier, M.D., MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and assistant professor of medicine at UCLA Health.

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