Most people with constipation do not need extensive testing and can be treated with changes in diet and exercise. The patient's medical history is the most important factor in diagnosing constipation. For example, in young people with mild symptoms, a medical history and physical examination may be all the doctor needs to suggest successful treatment. The tests the doctor performs depend on the duration and severity of the constipation, the person's age, and whether blood in stools, recent changes in bowel movements, or weight loss have occurred.

Medical History

The doctor may ask a patient to describe his or her constipation, including duration of symptoms, frequency of bowel movements, consistency of stools, presence of blood in the stool, and toilet habits (how often and where one has bowel movements). A record of eating habits, medication, and level of physical activity or exercise will also help the doctor determine the cause of constipation.

The clinical definition of constipation is any two of the following symptoms for at least 12 weeks (not necessarily consecutive) in the previous 12 months:

• straining during bowel movements
• lumpy or hard stool
• sensation of incomplete evacuation
• sensation of anorectal blockage/obstruction
• fewer than three bowel movements per week

A physical exam may include a rectal exam with a gloved, lubricated finger to evaluate the tone of the muscle that closes off the anus (anal sphincter) and to detect tenderness, obstruction, or blood. In some cases, blood and thyroid tests may be necessary to look for thyroid disease and serum calcium or to rule out inflammatory, neoplastic, metabolic, and other systemic disorders.

Extensive testing usually is reserved for people with severe symptoms, for those with sudden changes in number and consistency of bowel movements or blood in the stool, and for older adults. Additional tests that may be used to evaluate constipation include

• Colorectal transit study: This test, reserved for those with chronic constipation, shows how well food moves through the colon. The patient swallows capsules containing small markers that are visible on an x ray. The movement of the markers through the colon is monitored with abdominal x rays taken several times 3 to 7 days after the capsule is swallowed.

• Anorectal function tests: Anorectal manometry evaluates anal sphincter muscle function. For this test, a catheter or air-filled balloon inserted into the anus is slowly pulled back through the sphincter muscle to measure muscle tone and contractions.

Because of an increased risk of colorectal cancer in older adults, the doctor may use tests to rule out a diagnosis of cancer, including

• Barium enema x ray. This exam involves viewing the rectum, colon, and lower part of the small intestine to locate any problems. This part of the digestive tract is known as the bowel. This test may show intestinal obstruction and Hirschsprung's disease, a lack of nerves within the colon.

• Sigmoidoscopy or Colonoscopy: A sigmoidoscopic exam (using a lighted, flexible endoscope) is necessary to rule out a mechanical blockage of the lower bowel, such as a tumor. Colonoscopy is the visual exam of the inside of the entire colon using a flexible fiberoptic colonoscope. The exam is usually performed under mild sedation.