Extensive testing is usally not necessary for diagnosing constipation, and in most cases, the condition can be treated with changes in diet and exercise. For example, young people with mild symptoms may only require a medical history and physical examination; in many cases, this is all the doctor needs to put them on a course of successful treatment. If the doctor decides to perform tests, they will depend on:
* The duration and severity of the constipation
* The person’s age
* Whether blood in the stool, recent changes in bowel movements, or weight loss have occurred.
Diagnosing Constipation: Medical History
As part of a 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
* Toilet habits (how often and where one has bowel movements).
Keeping a record of your 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 blockage/obstruction in the anus or rectum
* Fewer than three bowel movements per week.
Diagnosing Constipation: Physical Examination
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 is usually reserved for older people or those with:
* Severe symptoms
* Sudden changes in number and consistency of bowel movements
* Blood in the stool.
Additional tests that may be used to evaluate constipation include:
* Colorectal transit study
* Anorectal function tests.
Because of an increased risk of colorectal cancer in older adults, the doctor may use tests to rule out a diagnosis of cancer. These tests include:
* Barium enema x-ray
* Sigmoidoscopy or colonoscopy.
Diagnosing Constipation: Colorectal Transit Study
A colorectal transit study, usually 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. The patient follows a high-fiber diet during the course of this test.
Diagnosing Constipation: Anorectal Function Tests
Anorectal function tests diagnose constipation caused by abnormal functioning of the anus or rectum. One such test, known as anorectal manometry, evaluates the function of anal sphincter muscle. For this test, a catheter or air-filled balloon is inserted into the anus and then slowly pulled back through the sphincter muscle to measure muscle tone and contractions.
Defecography is an x-ray of the anorectal area that:
* Evaluates how completely stool is eliminated
* Identifies anorectal abnormalities
* Evaluates rectal muscle contractions and relaxation.
During the defecography 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 and 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.
Diagnosing Constipation: Barium Enema X-ray
A barium enema 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, 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 colon and rectum, x-rays are taken. These x-rays reveal the shape and condition of the colon and recturm. The patient may feel some abdominal cramping when the barium fills the colon, but usually feels little discomfort after the procedure. Stools may be a whitish color for a few days after the exam.
Diagnosing Constipation: Sigmoidoscopy or Colonoscopy
An examination of the rectum and lower (sigmoid) colon is called a sigmoidoscopy. An examination of the rectum and entire colon is called a colonoscopy.
The patient usually has a liquid dinner the night before a sigmoidoscopy and takes an enema early the next morning. A light breakfast and a cleansing 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. 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 a mild sensation of abdominal pressure and wanting to move the bowels. Sometimes the doctor fills the colon with air to get a better view. The air may 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. The same bowel cleansing used for the barium x-ray is needed to clear the bowel of waste. The patient is lightly sedated before the exam. 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 temporarily feel gassy and bloated after the procedure.