Colorectal

What You Need to Know About Diagnosing Pediatric Functional Constipation

If your child has functional constipation and is not responding well to a bowel management program, pediatric colorectal specialists and gastroenterologists will perform a series of diagnostic tests to determine the underlying cause of the condition.

If your child is a candidate for surgery, the type of surgery your child will need and when to perform it is based on a comprehensive evaluation of the anorectal and colorectal anatomy and physiology.

Tests and Tools that Diagnose the Causes of Functional Constipation

Contrast Enema

A contrast enema is performed to assess if there are any abnormalities in the colon or distal small intestine. The test uses a special type of enema solution that can show up on an X-ray. X-rays are taken of the colon and lower intestine to check for Hirschsprung's disease as well as any other issues that may be causing constipation.

The following day, a plain abdominal X-ray may be performed to check for problems with colonic motility. If much of the contrast from the day before remains on a plain X-ray, then it is assumed that the child has a hypomotile (slow moving) colon. If the colon is empty the day after the contrast enema, this is an ideal time to initiate laxative therapy. Colonic hypermotility (excessive activity or movement of the colon) is suspected if the patient has fecal incontinence with a tendency toward diarrhea, a normal looking colon and no contrast on the follow-up X-ray.

Sitz Marker Study

A Sitz marker study involves the patient swallowing a type of gelatin capsule that contains tiny rings (markers), that once ingested, can show up on an X-ray. It’s important for the child to swallow all the rings. These “markers” are analyzed over the course of several days to help physicians estimate how fast or slow food and stool travels through the intestines.

A child with normal motility will have passed most of the markers by day four, and all of them by day seven. In a patient with total colonic inertia and almost no colon motility, these markers accumulate in the right colon. In patients with slow but steady colonic motility, the markers will be located predominately in the rectosigmoid colon. Other patients with segmental colonic dysmotility may have markers retained in the affected segment of the colon.

Sitz marker study demonstrating colonic dysmotility:

Sitz marker study demonstrating colonic dysmotility

Colonic Nuclear Transit Study (Colonic Transit Scintigraphy)

Colonic Manometric Tests

Children with chronic constipation with or without soiling who have failed other medical therapies are good candidates for colonic manometry. Colonic manometry tests measure and record the pressure waves that are produced when the large intestine contracts before and after eating. It is like an EKG for the heart, but the idea applied to the movement of the colon.

Learn more about colonic manometry.