Here is some anecdata:

When my son was a toddler, probably between 3 and 5 years old, he was severely constipated. I don't remember exactly why we took him to the dr. but he seemed to be in pain. We had to take him to a specialist that did x-rays and found how enlarged his rectum was. Treatment was enemas, mineral oil taken orally and/or laxative, Miralax (now OTC). At that time he was having accidents at night but also during the day. We thought he was too focused on whatever else he was doing that he didn't realize he needed to go. We never heard of a link between constipation and bed-wetting. Since he was having problems with constipation we decided that potty training could wait until this issue was resolved. After all, being wet was annoying (probably more for us than him) but the other problem was painful.

Unfortunately, after the constipation issue was resolved he continued having accidents even in grade school. I don't remember exactly when he stopped having them but if I have to guess I would say it was around age 9. I wish I had known about the link between these two issues to press for a better evaluation of when he was no longer constipated. We probably should have continued treatment even when he didn't seem to be in pain.

My suggestion would be to talk to his primary to refer to a specialist for the diagnosis and treatment of constipation.

- zol