Defecography

ROLE OF DEFECOGRAPHY IN DIAGNOSIS OF CHRONIC CONSTIPATION (ODS)

Background: Defecography (evacuation proctography) is a radiological contrast study of the process of defecation using fluoroscopic techniques.  Contrast material (e.g. barium) similar to the consistency of stool is placed into the rectum followed by fluoroscopy of the anorectal activity during squeezing, relaxation and while evacuating the barium.  Defecography has been proposed as a diagnostic test of constipation to evaluate lower bowel disorders that are not evident by direct visualization.

The American Gastroenterological Association (AGA) guidelines on constipation (2000) recommended a systematic approach to patients with constipation.  After the initial history and physical examination, patients may be classified into one of several subgroups:

1. irritable bowel syndrome,
2. slow-transit constipation,
3. rectal outlet obstruction,
4. a combination of slow-transit constipation and rectal outlet obstruction, (v) organic constipation, or
5. constipation secondary to systemic disease.

The aim of this study was to establish the impact of defecography on the management of patients with chronic constipation. 

• What is a Defecography?

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.

• 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)

• Preparation for the procedure –

Give enema to the patient 2 hours prior to the procedure. Repeat the enema after 15 minutes. Patient should keep NBM since 2 hours before procedure.

• Technique

In females, pre-procedural preparation involves smearing a small amount of barium contrast in the vagina with careful avoidance of the rectum.

The technique itself involves insertion of a caulk gun device into the rectum with subsequent manual infusion of barium paste until there is adequate distension. The patient is then transferred to a portable plastic commode which is situated next to an x-ray camera with recording of the defecation. Positioning of the x-ray camera is of paramount importance as visualization of the buttocks, rectal vault and lower pelvis is mandatory.