There is a trend towards consolidation in the healthcare industry. We're seeing hospitals buying up medical provider offices (or forming them). The main financial advantage is that they can then bill at hospital rates or bill for things like room charges without the actual hospital overhead. This article documents one example of this practice in Boston.
We're seeing this trend everywhere. I had a similiar experience in Chicago and have helped friends out with the same issue in places like Texas and Florida. This is one of the main reasons Rising's Surgical Specialist Network is needed and will help control healthcare costs.
For your own bills, take a look and make sure the doctors office is not billing you like a hospital. If so, you may want to look for a new provider. It costs you (and us) a lot more.