How is constipation diagnosed?

Most cases of constipation are mild and only require a physical exam for diagnosis. During the exam, your doctor will try to determine the cause of your constipation by asking questions about symptoms and any recent changes to your diet, lifestyle, or medications. Your doctor may also check your rectum, as constipation can cause fecal matter to build up in the intestines and rectum.

Dr. Lawrence S. Friedman, MD

Diagnosing constipation might sound simple, but in order to determine what's causing the problem—particularly if it persists and is severe—your doctor will need to ask questions about your health and symptoms and perform a physical exam. He or she will ask what medications you are taking, in case one of them could be contributing to the problem.

The physical exam may involve a visual and hands-on examination of your abdomen for any masses or tenderness. Your doctor may also perform a digital rectal exam (insertion of a gloved finger into the rectum) to feel for polyps or other abnormalities and to assess the strength of the anal sphincter muscle. He or she may perform one of several tests to help determine if there's a blockage in the colon or an underlying condition such as hypothyroidism.

Evaluating constipation may require special tests, including a colonic transit study (to measure how quickly stool passes through the colon), defecography (an imaging study of the rectum during attempted defecation), and anorectal manometry (to measure the pressure of anal contraction).


Since constipation may have one or more causes, it is important to identify the reason(s) for the constipation in order to correct the problem as simply, and as specifically, as possible.

Several tests of intestinal and anal function are available to help determine the cause or causes in each individual case. Examination of the anorectal area is usually the first step. Examination of the intestine, either with a flexible lighted instrument or with a barium x-ray study, may also be important.

A marker study, during which small markers, given by mouth, are followed for several days with repeated x-rays, can give clues to disorders of muscle function of the intestine itself.

Testing of the function of the anus and rectum during the act of elimination can be helpful in determining malfunction of the anorectal muscles, or internal disorders of the rectum such as a rectocele (a pocket forming just above the anal muscle) or rectal prolapse (a portion of the rectal wall sliding down to, or beyond, the anus).

Such tests may include video defecography (an x-ray of the function of the anorectal area) or anorectal manometry (which tests nerves and muscles of the anorectum).

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.