Beware: Medicare has ASCs in its pay-for-performance crosshairs. Perform surgery on the wrong knee, botch antibiotic administration or send a patient to your community's general hospital and you might get smacked with a 2 percent penalty on Medicare reimbursements. While no one is truly certain how pay for performance will play out in ASCs, you may have to report quality measures to CMS as early as 2009. Here's a breakdown of why and how you may soon have to prove that you deserve what you earn.