NASHVILLE — The TennCare Bureau announced today that BlueCross BlueShield of Tennessee (BCBST) and UnitedHealth Plan of River Valley, Inc. (United) are the prevailing bidders in both the East and West grand regions of the state for TennCare’s managed care organization (MCO) contracts. TennCare placed the managed care contracts up for competitive bid in January 2008. The Middle region’s competitive bid process was completed last year.