Q I have a ten-year-old son who has developed the habit of pooping his pants and/or not cleaning properly, leading to messy underwear almost daily. He had pooped his pants a few times and stated it was an accident and this was treated as such until it became a frequent thing. I talked with him about this and tried several tactics to resolve the issue with little results. Now he has soiled underwear almost all the time and tries to hide it. I'm concerned not only over the health and behavior aspects of this but also because when he does this he smells horribly and either doesn't realize this or doesn't care. He now makes statements that "no one likes him," "that's why nobody wants to hang out with him," "it's always his fault." These self-deprecating statements are increasing in frequency.
From what you are describing it sounds like your son might have a condition known as encopresis. Often when kids have encopresis it is because they have experienced a painful bowel movement and they want to avoid having that pain again, so they avoid pooping. But what happens when you withhold defecating is that the poop hardens and forms a mass. When you say that he is soiling his underwear, what’s likely happening is that he is having something called seepage. This means that the fluid that needs to get out is passing around the mass in his rectum, and that is what is creating the soiling.
So this means that your son needs to see a pediatric gastroenterologist, who will help him flush it out. Then, once the mass is flushed out, he will most likely be put on a stool softener for a period of time. To make sure that he is defecating each day, you will want to put some kind of reward system in place that he would find motivating. Crafting a motivating reward system is also something that you could work with a therapist on.