Is he able to use the potty on his own or still pretty much in the early stage of training? If he can go on his own I would keep a potty in his room, which would eliminate that excuse. I use an extra tall gate so my fearless climber can't get out of the room if he tried.
I would set down the rules, "Bedtime is now, you go potty before bed, if you have to go again YOU go, I'm not coming back in. I'm going to sleep now, and you need to, too." No bribes, rewards or threats. If a gate won't work try a door knob cover on the nob so he can't open the door or do what Dawn suggested, put the lock on the outside of the door. Also try one of the cool Cloud B night lights, they project a constellation of stars on the ceiling and stay on for 45 minutes:
http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3...
These don't plug into the wall, they're battery-operated.
Don't give in to him when he calls, just remind him that it's bedtime and he needs to go to sleep, engage as little as possible and don't go in the room. He may cry, he may scream, he may fall asleep in the middle of the floor, but he will learn to go to sleep on his own.
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Have to say, which I usually don't, that if someone doesn't agree with me that's fine, but to say my belief is "disgusting," have some respect. Just because you disagree with advice doesn't automatically make it wrong and yours right. Also realize that the person asking a question has the ability and right to make the best choice for their child, and is not obligated to take any of our advice. I actually thought this was the reason we were here, to share advice and have an opportunity to benefit from what we all know and have experienced, not dictate. Maybe i'm naive...
And, no, I'm not having a bad day, i just feel we ALL deserve to share our advice without being criticized. A little respect goes a long way.