Chronic constipation in children often leads to large, hard, difficult to pass bowel movements. As a result, the child may “hold back”, not completely emptying their colon when they poop to avoid pain. Or during times of stress or limited access to a toilet, a child may “hold back”. Regardless of why, as the child holds back, they slowly fill up their colon with stool, stretching it out bigger and bigger. Doctors often call this “megacolon”, meaning the colon is larger than normal. This is why children with chronic constipation or encopresis can pass bowel movements that are extremely large, sometimes large enough to clog the toilet.
Since children with chronic constipation often hold back, they don’t regularly empty the very bottom part of their colon (rectum), allowing their colon to continue removing water from waste and creating hard stools. This also means their rectum is often full. Normally, when we pass a bowel movement, we completely empty the colon. This means that most of the time, the rectum is empty. Once a day, twice a day, or every other day, some stool moves into the empty rectum and stretches it. It is this stretching that gives us the feeling or urge to pass a bowel movement. You respond to the urge by going to the bathroom and passing a bowel movement which empties your rectum.
Since children with chronic constipation and encopresis almost always have some stool in their rectum, the nerves that send the signal to the brain are constantly being stimulated. Over time, the nerve sensations in the rectum diminish and the child’s body ends up no longer recognizing the signal to poop. This is not a conscious decision, but something that just happens. It’s like living near a train station. At first, you hear trains pass by all the time. However, after a while, you don’t notice train noise. Children with chronic constipation and encopresis unconsciously tune out the normal signal to pass a bowel movement.
As the colon gets more and more stretched out of shape, soft or liquid stool from higher up in the colon begins to “leak” around the hard stool. This leakage may begin as small amounts that streak or stain the underwear. Most parents initially assume their child just isn’t wiping very well.
As the colon continues to stretch, the amount of leakage increases so that eventually children begin having poop accidents or encopresis, passing whole bowel movements in their pants. Because the accidents consist of stool that is from higher up in the colon that hasn’t been completely digested, the accidents are sometimes very dark and sticky, smell very bad, and have to be scraped off the skin and the clothing. And since the accidents are leakage of soft stool out of the colon, children often don’t feel the accidents happening. In fact, the child may not even be aware of the smelly poop odor coming from his pants. When this odor is constant, the smelling centers of the child’s brain become desensitized, leaving the child unaware of their own stinky smell. As a result, kids with encopresis, particularly those in school or other public settings, may need help from a caring adult to quickly let them know if they have a poop accident.