Aug 27 - Fitch Ratings has upgraded the ratings of Universal Health Services, Inc. (UHS), including the issuer default rating (IDR) to 'BB' from 'BB-'. The Rating Outlook is Stable. A full list of rating actions follows at the end of this release. The ratings apply to approximately $3.5 billion of debt at June 30, 2012. KEY RATING ISSUES --Credit metrics have improved significantly since the November 2010 Psychiatric Solutions, Inc. (PSI) acquisition. Fitch expects debt leverage (total de