__Vıllebrand – Iýrgens aýrýy__ - qannyń qalypty uıýynyń buzylysymen sıpattalatyn tuqym qýalaıtyn qan ketý aýrýy. Aýrý barysynda aǵzanyń qan júıesinde aqýyz bolmaıdy (fon Vıllebrand faktory) nemese ol qyzmetin durys atqarmaıdy. Munyń saldarynan qan qalypty uıymaı, jaraqat kezinde qan ketý kóp bolady.