Activated Partial Thromboplastin Time (APTT), Plasma
Method Description Describes how the test is performed and provides a method-specific reference
The activated partial thromboplastin time (APTT) assay results are determined by mixing patient plasma with HemosIL SynthASil reagent to provide optimal and uniform activation of the sample. After activation at 37 degrees C, the reaction is initiated by the addition of HemosIL SynthASil Calcium Chloride. The time, in seconds, required for the clot formation is then measured by the STA-R Evolution analyzer. The STA-R Evolution is a fully automated coagulation instrument that uses an electromagnetic viscosity detection system. The oscillation of a steel ball within the cuvette with the reagent and plasma is monitored by the STA-R Evolution. At the constant viscosity, constant pendular swings of the ball are obtained within an electromagnetic field. As the viscosity increases as a result of the coagulation, the oscillation amplitude of the ball swing decreases. An algorithm uses these variations in oscillation amplitude to determine the clotting time in seconds. (Package insert: HemosIL SynthASil, 2008; Operators manual: STA-R Evolution)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Sunday; Continuously