Having Shoulder Surgery 4 weeks after getting my Belly Button Ring, HelP?

Ok so I know that I will have to take out my belly ring for surgery, but I don't want it to close and I read that you can get a retainer or catheter type thing to replace it with the day of the surgery so it doesn't close. My question is how do you go about getting this done? Can they do it at the hospital during surgery prep? Or do I have to go back to the place I got it pierced and have them do it? And where do I get one of those retainers from?