platelet agglutination

It is no longer used clinically because it caused thrombocytopenia and platelet agglutination.

Thrombin-induced inhibition of platelet agglutination by von Willebrand factor (vWF): Reversal by ionized calcium.

Transmittance of light may be used to measure e.g. clearing of opacity of a liquid created by suspended particles due to decrease in number of clumps during a platelet agglutination reaction.

Read MS, Smith SV, Lamb MA, Brinkhous KM (1989) Role of botrocetin in platelet agglutination: formation of an activated complex of botrocetin and von Willebrand factor.

Platelet agglutination caused by ristocetin can occur only in the presence of von Willebrand factor multimers, so if ristocetin is added to blood lacking the factor (or its receptor - see below), the platelets will not clump.