Defecography, or evacuation proctography, is an X-ray test that shows the rectum and anal canal as they change during defecation (having a bowel movement). This test is used to evaluate for disorders of the lower bowel that are not evident by tests such as colonoscopy or sigmoidoscopy.
Preparing for the Procedure
- Give yourself a Fleet® enema two hours prior to your study. Repeat the enema after 15 minutes. You can purchase the enemas from a pharmacy or supermarket.
- You should not eat anything during the two hours prior to the procedure. If you are diabetic, this may involve adjusting your diabetic medications.
- You should take your regular medications with small sips of water at least two hours prior to the study.
The Defecography Test
Defecography is a technique in which a barium contrast medium is introduced into your rectum after the radiologist performs a rectal examination. The barium is visible within the rectum on X-rays. During the test, you are instructed to defecate (empty the rectum) on a commode while X-rays of the pelvis are taken. These X-rays are taken while the person is sitting at rest, straining, squeezing, and during defecation. This test allows the doctor to evaluate the pelvic floor muscles and rectum during defecation. This type of test, although awkward, provides valuable information that may aid your doctor in diagnosing your problem.
Occasionally X-rays of other areas are needed for the test. You may be asked to drink two cups of barium and two cups of water. This is done to show the small intestine in the pelvis if there is a problem with pelvic floor relaxation. Rarely, the radiologist will also fill the vagina in women with barium contrast.
When Is Defecography Used?
Defecation (having a bowel movement) is a complex action requiring coordination with relaxation and contraction of a large number of muscles. It is controlled by the nervous system, but is also under voluntary control. The process of defecation is initiated by the arrival of stool into the rectum. This sensation leads to a chain of events which ends in evacuation of stool from the anus. The act of defecation is voluntarily controlled in healthy, normally functioning people.
The following is a list of some conditions for which defecography can be used to gather more information about a patient's condition and/or confirm a diagnosis:
- Chronic constipation - evaluating for functional obstruction
- Rectal prolapse
- Rectocele (an outpouching of the rectum)
- Fecal incontinence
- Anismus (inappropriate spasm of the anal sphincter)
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Prepared by Henry Parkman, MD