How is the cause of constipation diagnosed?
To diagnose the cause of constipation, Dr. Jones will take a medical history, perform a physical exam, and order specific tests. The tests ordered depend on how long a patient has been constipated; how severe the constipation is; the person’s age; and whether the person has had blood in stools, recent changes in bowel habits, or weight loss. Most people with constipation do not need extensive testing and can be treated with changes in diet and exercise.

Medical History
Dr. Jones may ask questions about the person’s constipation, including how long symptoms have been present, frequency of bowel movements, consistency of stools, and presence of blood in the stool. Dr. Jones may also ask questions about the person’s eating habits, medication, and level of physical activity. A record of this information can be prepared before the visit to assist Dr. Jones in his diagnosis.

Physical Exam
A physical exam usually includes a rectal exam with a gloved, lubricated finger to evaluate the tone of the muscle that closes off the anus—called the anal sphincter—and to detect tenderness, obstruction, or blood. Nacogdoches Gastroenterology may perform a test for blood in the stool by placing a small sample of the person’s stool on a paper card and adding a drop or two of testing solution. A color change is a sign of blood in the stool.

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

• Blood test
• Lower G.I. series
• Flexible sigmoidoscopy or colonoscopy
• Colorectal transit studies
• Anorectal function tests
• Defecography

Blood test
A blood test can show if there may be an underlying disease or condition causing constipation. For example, low levels of thyroid hormone may indicate hypothyroidism.

Lower G.I. series
A lower G.I. series is an x-ray exam that is used to look at the large intestine. For the test, the person will lie on a table while a radiologist inserts a flexible tube into the person’s anus. The large intestine is filled with barium, a chalky liquid, making signs of problems that may be causing constipation show up more clearly on x-rays.

Flexible sigmoidoscopy or colonoscopy
The tests are similar, but a colonoscopy is used to view the rectum and entire colon, while a flexible sigmoidoscopy is used to view just the rectum and lower colon. In most cases, light anesthesia, and possibly pain medication, is used during a flexible sigmoidoscopy or colonoscopy. For either test, the person will lie on a table while Dr. Jones inserts a flexible tube into the anus. A small camera on the tube sends a video image of the intestinal lining to a computer screen. The test can show signs of problems in the lower G.I. tract.

Colorectal transit studies
These tests show how well food moves through the colon.

• Radiopaque markers: With this technique, the person swallows capsules containing small markers that are visible on an x-ray. The markers move through the G.I. tract just as food and waste do and are passed naturally with stool. During the course of this test, the person eats a high-fiber diet to help stool move through the G.I. tract. Three to 7 days after the person swallows the capsules, abdominal x-rays, taken several times, monitor the movement of the markers through the colon.
• Scintigraphy: This type of nuclear medicine study relies on the detection of small amounts of radiation after a person eats a meal containing radioactive chemicals. The dose of the radioactive chemicals is small; therefore, scintigraphy is not likely to cause damage to cells. Special external cameras and computers are used to create images of the radioactive chemicals as they move through the intestine.

Anorectal function tests
These tests diagnose constipation caused by anorectal dysfunction, which refers to problems with the anus and rectum.

• Anal manometry uses pressure sensors and a balloon that can be inflated in the rectum to check the sensitivity and function of the rectum. Anal manometry also checks the tightness of the anal sphincter muscles around the anus. For this test, a thin tube with a balloon on its tip and pressure sensors below the balloon is inserted into the anus until the balloon is in the rectum and pressure sensors are inside the anus. The tube is slowly pulled back through the sphincter muscle to measure muscle tone and contractions. The test takes about 30 minutes.
• Balloon expulsion tests consist of filling a balloon with varying amounts of water after it has been inserted into the rectum. The person is given a stopwatch and instructed to go to the restroom and measure the amount of time it takes to expel the balloon. If the person cannot expel a balloon filled with less than 150 milliliters of water or it takes longer than one minute to expel the balloon, the person may have a decrease in function for evacuation of stool.

Defecography
This x-ray of the anorectal area shows how well the person can hold and evacuate stool. During the test, Dr. Jones fills the rectum with a soft paste that shows up on x-rays. The patient sits on a toilet inside an x-ray machine. The patient is first asked to pull in and squeeze the sphincter muscles to prevent leakage. Then the patient is asked to strain to have a bowel movement. The radiologist studies the x-rays for anorectal problems that occurred as the paste was expelled.