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Constipation is defined as having a bowel movement fewer than three times per week. With constipation stools are usually hard, dry, small in size, and difficult to eliminate. Some people who are constipated find it painful to have a bowel movement and often experience straining, bloating, and the sensation of a full bowel.
Constipation is a symptom, not a disease. Almost everyone experiences constipation at some point in their life, and a poor diet typically is the cause. Most constipation is temporary and not serious. Understanding its causes, prevention, and treatment will help most people find relief.
Constipation is one of the most common gastrointestinal complaints in the United States. More than 4 million Americans have frequent constipation, accounting for 2.5 million physician visits a year. Those reporting constipation most often are women and adults ages 65 and older. Pregnant women may have constipation, and it is a common problem following childbirth or surgery.
To understand constipation, it helps to know how the colon, or large intestine, works. As food moves through the colon, the colon absorbs water from the food while it forms waste products, or stool. Muscle contractions in the colon then push the stool toward the rectum. By the time stool reaches the rectum it is solid, because most of the water has been absorbed.
Constipation occurs when the colon absorbs too much water or if the colon's muscle contractions are slow or sluggish, causing the stool to move through the colon too slowly. As a result, stools can become hard and dry. Common causes of constipation are
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 habits, or weight loss have occurred. Most people with constipation do not need extensive testing and can be treated with changes in diet and exercise. For example, in young people with mild symptoms, a medical history and physical exam may be all that is needed for diagnosis and treatment.
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 will also help the doctor determine the cause of constipation.
The clinical definition of constipation is having any two of the following symptoms for at least 12 weeks (not necessarily consecutive) in the previous 12 months:
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, metabolic, and other disorders.
Extensive testing usually is reserved for people with severe symptoms, for those with sudden changes in the number and consistency of bowel movements or blood in the stool, and older adults. Additional tests that may be used to evaluate constipation include
Because of an increased risk of colorectal cancer in older adults, the doctor may use tests to rule out a diagnosis of cancer, including a
Colorectal transit study. This test 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 by abdominal x rays taken several times 3 to 7 days after the capsule is swallowed. The patient eats a high-fiber diet during the course of this test.
Anorectal function tests. These tests diagnose constipation caused by abnormal functioning of the anus or rectum (anorectal function).
Defecography is an x ray of the anorectal area that evaluates completeness of stool elimination, identifies anorectal abnormalities, and evaluates rectal muscle contractions and relaxation. During the exam, the doctor fills the rectum with a soft paste that is the same consistency as stool. The patient sits on a toilet positioned inside an x-ray machine, then relaxes and squeezes the anus to expel the paste. The doctor studies the x rays for anorectal problems that occurred as the paste was expelled.
Barium enema x ray. This exam involves viewing the rectum, colon, and lower part of the small intestine to locate problems. This part of the digestive tract is known as the bowel. This test may show intestinal obstruction and Hirschsprung's disease, which is a lack of nerves within the colon.
The night before the test, bowel cleansing, also called bowel prep, is necessary to clear the lower digestive tract. The patient drinks a special liquid to flush out the bowel. A clean bowel is important, because even a small amount of stool in the colon can hide details and result in an incomplete exam.
Because the colon does not show up well on x rays, the doctor fills it with barium, a chalky liquid that makes the area visible. Once the mixture coats the inside of the colon and rectum, x rays are taken that show their shape and condition. The patient may feel some abdominal cramping when the barium fills the colon but usually feels little discomfort after the procedure. Stools may be white in color for a few days after the exam.
Sigmoidoscopy or colonoscopy. An examination of the rectum and lower, or sigmoid, colon is called a sigmoidoscopy. An examination of the rectum and entire colon is called a colonoscopy.
The person usually has a liquid dinner the night before a colonoscopy or sigmoidoscopy and takes an enema early the next morning. An enema an hour before the test may also be necessary.
To perform a sigmoidoscopy, the doctor uses a long, flexible tube with a light on the end, called a sigmoidoscope, to view the rectum and lower colon. The patient is lightly sedated before the exam. First, the doctor examines the rectum with a gloved, lubricated finger. Then, the sigmoidoscope is inserted through the anus into the rectum and lower colon. The procedure may cause abdominal pressure and a mild sensation of wanting to move the bowels. The doctor may fill the colon with air to get a better view. The air can cause mild cramping.
To perform a colonoscopy, the doctor uses a flexible tube with a light on the end, called a colonoscope, to view the entire colon. This tube is longer than a sigmoidoscope. During the exam, the patient lies on his or her side, and the doctor inserts the tube through the anus and rectum into the colon. If an abnormality is seen, the doctor can use the colonoscope to remove a small piece of tissue for examination (biopsy). The patient may feel gassy and bloated after the procedure.