Hi I know this doesn't really help, but it depends on how bad it is.
My Daughter was very ill last year and wet the bed quite a few times, after she was better I tried everything to get out the smell starting with soapy water, then fabreeze, then a bissel power cleaner and nothing worked so in the end I bought her a new matress (and all new bedding).
Coz I had to spend money I didn't really I have I have been very careful with her new matress.
The best advice I can give for the future is make sure you buy a waterproof matress protector, and buy a low tog quilt. Put the low tog quilt over the matress, put the matress protector on top of that and then your bottom sheet. That was if anything does get through the matress protector chances are the quilt will soak it up and you can just chuck that in the wash.
Its worked for me!