The serum prothrombin consumption test, described by Quick,1 has not been commonly used because of its complicated technique. A simplified method using commercially prepared reagents, described by Wald, Weiner, and Sussman,2 is now available. The test can easily be performed in any laboratory where plasma prothrombin determinations are done. No single explanation for the coagulation of blood has as yet been generally accepted, nor has unanimity on the matter of terminology been reached; however, practically all of the recently expounded theories by Seeger, Quick, Owren, and Ware are schematically represented in figure 1.
The plasma prothrombin time measures deficiencies of the prothrombin complex. Thus a reduction in prothrombin, either congenital or acquired by the administration of bishydroxycoumarin (Dicumarol) and similar drugs is easily demonstrated. Any reduction in accessory factors (labile factor3 or Owrens factor 54) is similarly shown by a long plasma prothrombin time.