Laboratory Corporation of America Holdings is a clinical laboratory company in the United States. As of December 31, 2011, the Company had a national network of 54 primary laboratories and over 1,700 patient service centers (PSCs) along with a network of branches and STAT laboratories (which are laboratories that have the ability to perform certain routine tests quickly and report the results to the physician immediately). Through its national network of laboratories, the Company offers a range of clinical laboratory tests that are used by the medical profession in routine testing, patient diagnosis, and in the monitoring and treatment of disease. In addition, the Company has developed specialty testing operations, such as oncology testing, human immunodeficiency virus (HIV) genotyping and phenotyping, diagnostic genetics and clinical trials. During the year ended December 31, 2011, the Company acquired Clearstone Central Laboratories and Orchid Cellmark, Inc.