A blood test that measures the length of time (in seconds) that it takes for clotting to occur when certain substances are added to the liquid portion of blood in a test tube. It is used to detect clotting factor deficiencies and to monitor heparin’s effectiveness.
National Alliance for Thrombosis and Thrombophelia. 2009. GLossary of Blood Clot and CLotting Disorder Terms. Retrieved October 23, 2009 from http://www.stoptheclot.org/learn_more/glossary.htm