When somebody suffers from encopresis it means that he or she can't control their bowel movements and pass bowel movements in their underwear. "Soiling" and "fecal incontinence" mean the same thing.
What causes encopresis?
In most cases, encopresis develops as a result of long-standing constipation. The vast majority of of children suffering from encopresis have a history of constipation or a history of passing large and/or painful bowel movements. In many cases, the child or the parents do not recall the constipation since it was so long ago.
With constipation and painful bowel movements, children may not completely empty themselves when they go to the bathroom. Over a long period of time the large intestine slowly fills with stool and stretches out of shape. As the large intestine stretches larger and larger, liquid stool from the small intestine begins to "leak" around the more formed stool in the colon. In the beginning, this leakage is usually small amounts that streak or stain the underwear and most parents just assume the child isn't wiping very well.
As the intestine stretches further, the amount of leakage increases so that eventually children begin having "accidents" — they pass whole bowel movements in their underwear! Because these stools are "leaking" through the intestine and not getting completely digested, they are usually very dark and sticky, smell very badly, and have to be scraped off the skin and clothes.
Children don't usually feel these "accidents" happening — they just seem to happen. Accidents tend to occur more often during the daytime when the child is active and moving around, and only rarely do they occur at night while the child is asleep.
In most cases, encopresis is not primarily a behavioral problem. Children do not have these accidents out of spite or because they are lazy. Instead, many behavioral problems develop because of the encopresis, and once the encopresis is treated, many of the behavioral problems may resolve.