International Council for Standardization in Haematology (ICSH) recommendations for the performance and interpretation of activated partial thromboplastin time and prothrombin time mixing tests

This guidance document has been prepared on behalf of the International Council for Standardization in Haematology (ICSH). The aim of the document is to provide guidance and recommendations for the performance and interpretation of activated partial thromboplastin time (APTT) and prothrombin time (PT) plasma mixing tests in clinical laboratories in all regions of the world. The following areas are included in this document: preanalytical, analytical, postanalytical, and quality assurance considerations as they relate to the proper performance and interpretation of plasma mixing tests. The recommendations are based on good laboratory practice, published data in peer‐reviewed literature, and expert opinion.