Quality in coagulation and haemostasis testing

The essential elements of a quality program, specifically internal quality control (IQC) and external quality assurance (EQA), should be applied to each laboratory assay performed in order to ensure test result accuracy and precision. The coagulation laboratory plays an important role in the diagnosis and treatment of individuals with bleeding or clotting (i.e., thrombotic) disorders. Test methodologies used to assess common disorders or diseases of haemostasis are reviewed as well as the clinical relevance of each assay. The preanalytical phase of testing offers the greatest opportunity for introducing result error in the haemostasis laboratory and it is therefore imperative that samples are properly collected, transported and stored. Samples for haemostasis testing should be collected in 3.2% sodium citrate at a 9:1 blood to anticoagulant ratio and maintained at room temperature until processed. Some test processes such as platelet function testing have special processing and testing requirements. For plasma-based tests, centrifugation to obtain platelet poor plasma and testing should ideally be completed within 4 hours or the plasma frozen. IQC must be performed with each assay, at appropriate levels of the analyte and at appropriate time intervals as a means for assessing ongoing assay performance. EQA, a peer group assessment process that is supplementary to IQC, offers in addition the opportunity for evaluation of long-term performance of laboratories, including comparisons with like and unlike methodologies, and often serves as an educational resource. Participation in an EQA program is often a requirement of laboratory accreditation and there are a multitude of EQA organizations that offer programs specific to haemostasis testing with international programs providing assessment of the more specialized haemostasis assays. These programs provide invaluable information on assay specific diagnostic error rate, assay precision, accuracy, sensitivity and assessment of overall assay performance. The incorporation of IQC and EQA into a laboratory program can not only assist in the assurance that testing is reliable and accurate but also improve the quality of the testing.