Rapid preparation of plasma for coagulation testing.

Currently recommended minimum centrifugation of whole blood to produce platelet-poor plasma for routine coagulation assays is 1000g relative centrifugal force for 10 minutes. Many clinical laboratories centrifuge blood for routine coagulation assays from 500g to 2000g, with spin times varying from 20 to 5 minutes. Ninety blood samples, routinely submitted to our coagulation laboratory, were prospectively assayed simultaneously for the prothrombin time, activated partial thromboplastin time, and fibrinogen level, comparing centrifugation at 11,000g for 2 minutes with centrifugation at 1000g for 10 minutes. Routine and readily available equipment and supplies were used. Platelet counts were performed on the supernatant plasma in each sample to determine the efficacy of platelet depletion. Excellent correlation of methods was observed for the prothrombin time, activated partial thromboplastin time, and fibrinogen level. Platelet counts on the plasma supernatant showed no significant difference between the two centrifugation methods. We concluded that high-speed centrifugation at 11,000g with a shortened spin time of 2 minutes and with the use of routinely available equipment and supplies can significantly decrease the specimen preparation time for routine coagulation testing.