Are diagnostic tests necessary in constipation?

The doctor may ask the patient to describe their constipation in detail. That is, the duration of symptoms, the frequency of stools, the consistency of the stools, the presence of blood in the stools and his toilet habits, e.g. how often and where he stools. Recording dietary habits, medication and level of physical activity or exercise also help the doctor determine the cause of constipation.

The physical examination may include a finger examination, with a lubricated glove, in order for the doctor to evaluate the muscle tone that closes the anus (anal sphincter) to detect tenderness, obstruction or blood. In some cases, blood and thyroid tests may be necessary.
Extended tests are usually reserved only for people with severe symptoms or sudden changes in the number and consistency of stools, or for those who have detected blood in the stool and for older adults. Specifically, in older adults, because of the increased risk of colorectal cancer, the doctor may use the following tests to rule out a diagnosis of cancer:

• Barium enema X-ray
• The sigmoidoscopy or colonoscopy
• The colonic transit study
• The rectal function tests

A barium enema X-ray involves viewing the rectum, colon and lower small bowel to identify any problems. This test can show intestinal obstruction and Hirschsprung’s Disease, which is a lack of nerves inside the colon.

The night before the test, a “bowel prep” is necessary to clean out the lower digestive tract. The patient drinks about 250 grams of a special liquid every 15 minutes for about 4 hours. This liquid flushes the bowel. A clean bowel is important, because even a small amount of stool in the large intestine can hide the evidence and lead to an inaccurate test.

Because the colon does not show up well on an X-ray, the doctor fills the organs with barium hypo, an off-white liquid, to make the area visible. Once the mixture is coated on the organs, the X-rays reveal their shape and condition. The patient may feel some abdominal cramping when the barium fills the colon, but usually feels discomfort shortly after the procedure. The stools may have a whitish color for a few days after the tests.

The examination of the rectum and lower colon, sigmoid, is called sigmoidoscopy. Examination of the rectum and the entire colon is called a colonoscopy.

The night before the sigmoidoscopy, the patient usually has a liquid meal and is given an enema in the early morning. A light breakfast and a cleansing enema one hour before the test may also be necessary.

To perform the sigmoidoscopy, the doctor uses a long, flexible tube, with a light at the end, called a sigmoidoscope. This is used to see the rectum and the lower part of the colon. First, the doctor does a finger prick. Then, he inserts, through the anus, the sigmoidoscope into the rectum and the lower part of the colon. The procedure may cause a mild sensation of wanting to void as well as an abdominal pressure. Sometimes the doctor fills the organs with air to get a better view, which can also cause mild cramping.

Finally, to perform a colonoscopy, the doctor uses a flexible tube with a light on the end, called a colonoscope. With this he can see the entire colon. This tube is longer than a sigmoidoscope. It takes the same procedure to clean the bowel as a Barium X-ray. The patient is lightly sedated before the examination. During the examination, he or she lies on his or her side and the doctor inserts the tube, through the anus and rectum, into the colon. If the doctor notices any abnormality, he or she may use the colonoscope to remove a small piece of tissue for examination, a biopsy. After the procedure, the patient may feel that they have gas and swelling.

This test, intended for people with chronic constipation, shows how well food moves through the colon. The patient swallows some special capsules that have small marks, which are visible on the X-ray. The movement of the marks through the colon is monitored by X-rays of the abdomen, which are usually taken 3 to 7 days after the capsule is swallowed. During this examination, the patient follows a high-fiber diet.