4 1/2 yr old poops in pants

My son has been potty trained since he was 3 yrs old. Now that he is about to turn 5, I am deeply concerned about his accidents with Bowl Movements. He simply will not go to the bathroom if he doesn't feel like it! I usually catch him sitting on one of his legs as he is trying to hold it in. He also urinates in his pants quite often. I have asked his Pediatrician about this and he says that my son is just normal and doesn't want to take the time out to go. I am really getting concerned especially since he will be starting kindagarten soon. (PS: he has very normal bowel movements - no constipation or diarrhea.)
Any advice you can give me will be appreciated.

[Kevin Kennedy, Ph.D.]

If this behavior has been consistent, your son actually has not been fully trained to use the toilet. If he had been doing fine, and this behavior is of sudden onset, it might indicate some unsettledness in his environment, though probably this is not the case. Establish an incentive system for him, whereby he is rewarded each time he uses the toilet. Stay away from any disciplinary approach at this time. Also consider having him sit on the toilet at established times, particularly if there is a pattern to his bowel movements.

[dwsk]

A related discussion, Grandaughter won't use toilet anymore was started.