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.

Evaluation of chromogenic factor IX assays by automated protocols.

INTRODUCTION: Chromogenic substrate assays (CSA) to measure Factor IX (FIX) have recently become commercially available. However, information on their performance characteristics and use in diagnostic haemostasis laboratories remains limited. AIM: To evaluate the Hyphen Biomed (Hyphen) and Rossix FIX CSAs on fully automated coagulation analysers and compare them to the FIX one-stage assay (OSA). This study was conducted in a tertiary referral haemostasis laboratory associated with a haemophilia treatment centre. METHODS: Automated CSA protocols were adapted to the Sysmex CS2500 (CS2500) and Diagnostica Stago STA-R (STA-R) analysers. Samples assayed were from healthy volunteers, haemophilia B patients and FIX deficient plasma spiked with either plasma derived, recombinant or extended half-life FIX products. RESULTS: Reference intervals for Hyphen and Rossix assays were 73 IU/dL to 164 IU/dL and 73 IU/dL to 168 IU/dL, respectively, on the CS2500 analyser; and 84 IU/dL to 165 IU/dL for the Rossix assay on the STA-R. Repeatability across all method/analyser combinations resulted in CVs ranging from 0.8% to 5.4%. Between run reproducibility gave CVs <6.7% for all method/analyser combinations. In spiked samples, FIX recoveries were mostly within an acceptable limit of 100 ± 25% for BeneFIX® , Rixubis® and Alprolix® with some differences between CSAs. CONCLUSION: Both commercial factor FIX CSA kits can be adapted for Stago and Sysmex automated coagulation analysers. Reagent cost and workflow practices will need to be considered. These assays are potentially more consistent than OSA in measurement of replacement FIX products in haemophilia B patients.

A computerized expert system for handling the output of the Technicon H1 haematology analyser.

A computer-based expert system is described which handles the output of the Technicon H1 in the haematology laboratory of a large teaching hospital. Using patient request data, analyser results, error and morphology flags, the expert system decides; whether to validate the main indices plus differential; whether a blood film is required for manual review; and which abnormal results require phoning to the requesting doctor. The results of this computer-assisted analysis are sent to a printer adjacent to the analyser. The print-out details any further action required of the operator before release of results to the main hospital computer, and serves as a log of all samples run on that analyser. Benefits of the expert system include greatly simplified interpretation of the large array of analyser flags, and consistency in sample handling for all operators over all shifts.

Evaluation of the Technicon H-1 hematology analyser.

The Technicon H-1 is a new, random-access hematology instrument performing a full blood count with leukocyte differential including eosinophils and basophils. Technical assessment showed good linearity and precision. Comparison with a Coulter S-PLUS (II) showed close correlation for all full blood count parameters except MPV and MCHC on 149 unselected hospital inpatients over a wide clinical range. No significant carry-over was detected in hemoglobin, red cell, white cell and platelet estimations. Differentials agreed closely with Technicon H6000 results for neutrophils, lymphocytes, monocytes and eosinophils. Poorer correlation with 100-cell manual differentials for all cell types except neutrophils probably reflects the relative lack of precision in manual methods. Technological innovations on the H-1 include a laser-based optical system from which several new hematological parameters are derived. The contribution they make towards improved patient care awaits assessment.