Preanalytical phase in coagulation testing : state of the art in the laboratories of the Piedmont region, Italy

The control of preanalytical variables is critical, particularly for coagulation assays, since this has a direct influence on the quality of results and on their clinical reliability. The aim of the study was to evaluate the extent of information about preanalysis in the laboratories of a large region of northern Italy that perform tests of haemostasis. A questionnaire was sent concerning the number of coagulation analyses per year, the system of blood drawing, the anticoagulants and the tubes in use, the amount of blood collected, the tendency to reject unsuitable specimens, the storage temperatures, the times between collection and analysis, the conditions of tube centrifugation and identification, and the presence of staff specifically occupied in coagulation testing. Complete answers were offered by 136 laboratories (81%; 69 private and 67 public) that reported a total amount of 3,648,000 determinations per year. Statistical analysis was carried out on the findings of the investigation, in order to assess their significance and to detect possible correlations between the variables under consideration. The results show significant attention being given by laboratories to the preanalytical phase. This is also indicated by the large percentage of complete answers obtained. Some of the important positive aspects shown in the study are: (1) the preference for the closed system for blood sampling; (2) the prevalent use of primary tubes for testing; (3) a strong tendency to reject incorrect samples for analysis. On the other hand, a major problem seems to lie in the delay, particularly in some big centres, in processing of specimens, which can be critical for the correct performance of coagulation assays. The data obtained reflect with good reliability the overall situation in coagulation-testing laboratories in northern Italy.