The contact activation (intrinsic) pathway is initiated by activation of the "contact factors" of plasma, and can be measured by the activated partial thromboplastin time (aPTT) test.
A vía de activación por contacto (intrínseca) iníciase pola activación de dos "factores de contacto" plasmáticos, e pode medirse polo test do tempo de tromboplastina parcial activado (aPTT).