Defecography

Definition
Purpose
Precautions
Description
Preparations
Aftercare
Risks
Normal results

Definition

Defecography is an imaging test in which x rays are taken of the rectum and anal canal during the course of defecation.

Purpose

Defecography is used to evaluate the muscles needed for bowel evacuation and the surrounding tissues. It is used during the evaluation of a number conditions, including:

• Intussusception
• Rectal prolapse
• Rectocele
• Enterocele
• Cystocele
• Vaginal prolapse
• Chronic constipation
• Fecal incontinence
• Anismus

Precautions

Patients must carefully follow directions regarding when to stop eating and drinking, and when to begin their bowel prep. Patients who are diabetic may

KEY TERMS

Anismus— Dysfunctional contraction or spasm of the muscle comprising the anal sphincter.

Constipation— Difficulty passing a bowel movement. May refer to infrequent passage of stool, or to a hard, dry stool requiring straining and physical effort in order to pass.

Cystocele— Sagging or bulging of the bladder through the front wall of the vagina.

Enterocele— Sagging or bulging of an area of the intestine into the vagina.

Fecal incontinence— Involuntary passage of stool.

Intussusception— Telescoping of one part of the intestine or the rectum into the neighboring part.

Rectal prolapse— Sagging or bulging of the lining of the rectum into the rectum or actually through and out of the anal opening.

Rectocele— Sagging or bulging of the rectum through the back wall of the vagina.

Vaginal prolapse— Weakening of the supportive tissues of the uterus and vagina, such that the uterus and cervix bulge into the vaginal canal, or even out through the vaginal opening.

need to talk to their physician about adjusting their insulin schedule in response to fasting.

Description

Patients who are undergoing defecography are asked to drink several glasses of water, along with a barium contrast solution, upon arrival at the testing site. An hour later, a barium paste will be inserted into the patient’s rectum and (for women) into the vagina. Alternatively, some sites have an artificial stool preparation that can be used for this same purpose. The advantage of the artificial stool is in its greater textural similarity to natural stool.

The patient will be asked to sit on a special commode. The barium paste will show up on x rays taken with it in place. A variety of x-ray views will be taken while the patient is at rest, while they are squeezing the pelvic muscles, and while they are straining during evacuation of the barium paste from their rectum.

Preparations

The patient is usually asked to stop eating and drinking for the two hours before they are scheduled to have defecography. Two hours prior to the test, the patient may be asked to self-administer an enema. The enema is usually repeated fifteen minutes later.

Aftercare

After the test, patients are asked to drink extra water, in order to rid all of the barium from their system. Normal diet and activity can usually be resumed directly following completion of the test.

Risks

The greatest risk of this examination is one of embarrassment to the patient. Some patients find themselves unable to evacuate their bowels while under examination.

Normal results

This test assesses how quickly and completely the rectum is emptied, the angle of the anus and rectum (compared to known normal values of the anorectal angle), and the degree to which the perineum descends during straining. Structural abnormalities can also be demonstrated during defecography, including vaginal and/or rectal prolapse, intussusception, and recto-, enter-, and cystocele. Dysfunctional contraction of the anal sphincter can also be identified during defecography.

Resources

BOOKS

Feldman, M., et al. Sleisenger & Fordtran’s Gastrointestinal and Liver Disease. 8th ed. St. Louis: Mosby, 2005.

PERIODICALS

Morgan, D. M. “Symptoms of anal incontinence and difficult defecation among women with prolapse.” American Journal of Obstetrics and Gynecology 197 (November 2007): 509e1–6.

Rao, S. S. “Constipation: evaluation and treatment of colonic and anorectal motility disorders.” Gastroenterological Clinics of North America 36 (September 2007): 687–711.

Rosalyn Carson-DeWitt, MD