Contrast Enemas in Pediatrics
There are several reasons why doctors recommend that children have a contrast enema--a procedure that uses air contrasted with another substance to better visualize the inside of the colon. When polyps, tumors, or other irregularities in the colon are suspected, a double contrast enema, using a dilute suspension of barium and air in a colon that has been thoroughly cleaned, can reveal if these irregularities are present in the colon. In most cases, however, contrast enemas in children are ordered because of problems of constipation.
For patients with constipation due to poorly functioning nerves and muscles within their colons, contrast enemas are very valuable to help determine the extent of the problem and plan for treatment. We emphasize that when patients receive contrast enemas for these purposes, the colon should not be cleaned prior to the contrast enema study since we want to learn about the degree of constipation and fecal impaction the patient experiences. We also want to know how the patient empties the colon after the study. It is our policy that for these purposes, a contrast enema test never be done with barium, since barium provokes very severe impaction. The barium becomes petrified in the colon and often the patient has to be taken to the operating room to remove the impaction.
Possible Reasons for Constipation
Hirschsprung's disease, a birth defect in which the large intestine is lacking certain nerve cells and unable to move stool through, has been one diagnostic possibility in constipated children. In recent years, however, we have been detecting cases of Hirschsprung's disease very early in life, as pediatric radiologists gain experience in diagnosing the disease in newborns and more studies on the disease and its diagnoses are published in the literature.
It is now extremely unusual for Hirschsprung's disease to be diagnosed in older children in the United States. This is due not only to the disease being diagnosed earlier in life but to the high mortality rate—about 50% before school age—among those whose disease is not diagnosed and treated. Therefore, we almost never encounter a school age child with newly diagnosed Hirschsprung's disease.
Most preschool or school-age patients with constipation have a condition called idiopathic constipation or colonic inertia, although the condition has also received many other names in the literature. The term "idiopathic" means that we do not know the origin of the problem. Yet this problem afflicts thousands of children in the United States and can be extremely debilitating and incapacitating. Idiopathic constipation can also provoke psychological problems when the large amount of stool inside the rectum forces tiny amounts to slip out, soiling or smearing the underwear, creating an odor around the child, and causing the child to become socially unacceptable at school.
While there are no well established causes of this type of constipation, there is evidence that these patients suffer from some form of colon hypomotility disorder, meaning slow movement of food through the digestive tract. Radiological studies such as X-rays reveal these patients usually have varying degrees of enlargement of their colons, particularly the sigmoid section of the colon. This condition is known as megacolon or megasigmoid.
A significant number of these patients may show a very dilated and floppy rectosigmoid (the area where the sigmoid section of the colon joins with the rectum), with poor functioning, but with a conspicuously normal transverse and descending colon with visible peristalsis. This is the wavelike movement of muscles that pushes food through the digestive tract. On the other hand, some patients have homogenous dilation and abnormally slow peristalsis (hypoperistalsis) throughout the entire large bowel.
In Severe Cases, Surgery May Be Needed
In cases of severe megasigmoid, we have been performing resections of the rectosigmoid, preserving the rectum. Our experience shows that when the most dilated part of the rectosigmoid is limited to a particular segment, surgically removing that segment and rejoining the normal looking descending colon to the rectum cures the patient dramatically. When the patients have a homogeneous dilatation of the entire colon, however, resection of the sigmoid does not improve the condition. A total colectomy, removal of the entire colon, could cure some of these patients.
Patients that suffer from a condition known as intestinal pseudo-obstruction may need a terminal ileostomy. Intestinal pseudo-obstruction causes symptoms of bowel obstruction, but when the intestines are examined, no obstruction is found. Problems in how the muscles and nerves in the intestines work cause the symptoms. In severe cases of intestinal pseudo-obstruction, the colon and rectum are removed and an ileostomy is performed to make an opening in the abdomen and attach the bottom of the small intestine to allow stool to leave the body.
When surgery is needed, contrast enemas are very valuable to help determine the extent of the problem and determine the type of surgery needed.
Contact the Colorectal Center
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