Constipation occurs when stool remains too long in the colon or stool moves too slowly through the colon. As stool remains in the colon, fluid is reabsorbed by the body. The longer the stool remains, the more fluid is reabsorbed. This can make the stool hard and small. As this stool remains in the colon, more stool will accumulate. These stools can combine and make very large stools. Eventually the entire colon can fill with stool. The accumulation of stool can then cause the colon to stretch, which then causes the stool to move even slower through the colon and makes the problem worse.
In some cases, constipation is obvious, as in situations where the child is passing hard, dry, pellet-like stools with straining or only has a bowel movement every few days. Other signs of constipation include; large bowel movements, stomach ache, clogging the toilet with stool, soiling/smearing (sometimes referred to as “skid marks”) in the underwear. The soiling and smearing of stool is caused by liquid stool finding its way around the retained hard stool and eventually leaking to the underwear.
Constipation in children is almost always caused by withholding of stool. One common reason children will withhold stool is due to fear of stooling, maybe because of a past painful stool. Another reason is that many children do not like to stool outside the home, maybe because of “dirty bathrooms at school”. Young children, unlike adults and adolescents, rarely become constipated because of poor diet.
Constipation and Urology
There is a close relationship between the muscles and nerves that control bladder functions and those that control bowel movements. In addition, the bladder and the colon are close together in the body. Large amounts of stool in the colon can put pressure on the bladder which can cause the bladder to not fill as much as it should, or cause the bladder to contract when the bladder is not supposed to contract. This large amount of stool can also cause the bladder to not empty well. All of these problems can lead to daytime wetting, nighttime wetting, urinary tract infections, and in some cases vesicoureteral reflux (see separate handouts).
It is important to treat your child’s constipation to help treat your child’s bladder symptoms. Constipation treatment has two parts. The first part is to “clean out” the colon of all the retained stool. This usually takes a few days and can be done over a long weekend. In some cases the clean out may need to be repeated. The second part is to keep the colon cleaned out while the bowel and bladder heal. The maintenance phase can take 6-12 months. Both phases require medication. Because poor diet didn’t cause the constipation, usually changes in the diet do not cure the problem. This is different in adults where poor diet is often the cause of constipation.