International Council for Standardization in Haematology (ICSH) recommendations for "surrogate reference" method for the packed cell volume.

The spun packed cell volume (PCV, hematocrit) is a key measurement on which are based hematology instrument calibration, reference range determination, and assignment of values to calibrators/controls. In 2001, the International Council for Standardization in Haematology (ICSH) recommended a Reference PCV method, which is fully traceable to the ICSH reference hemoglobin method. Because of its complexity, however, this method is impractical for occasional use in routine laboratories and is therefore intended primarily for use by manufacturers of capillary microhematocrit tubes, liquid calibrators, and multichannel analyzers. In response to the need for a simpler method--accessible to all routine laboratories--the ICSH offers this "Surrogate Reference" PCV procedure. It is traceable to the original ICSH Reference PCV method and is based on spun PCVs obtained using borosilicate capillary tubes with an already-known relationship to this reference procedure. This ICSH "Surrogate Reference" PCV method is substantially simpler, thus putting it within the reach of most routine hematology laboratories.

College of American Pathologists Conference XXXI on laboratory monitoring of anticoagulant therapy: laboratory monitoring of unfractionated heparin therapy.

OBJECTIVE: To review the state of the art as reflected in the medical literature and the consensus opinion of recognized experts in the field regarding the laboratory monitoring of unfractionated heparin therapy. DATA SOURCES, EXTRACTION AND SYNTHESIS: The authors made an extensive review of the literature. The draft manuscript was circulated to every participant in the consensus conference prior to the convening of the conference. Extensive discussion concerning all of the issues addressed in the manuscript as well as the resulting recommendations occurred. This information was then used to revise the manuscript into its final form. CONCLUSIONS: The resulting manuscript has 23 specific recommendations regarding preanalytic, analytic, and postanalytic phases of monitoring and testing for complications related to unfractionated heparin therapy. This report contains detailed discussion of these recommendations and includes literature citations that support them. A number of issues for which consensus could not be reached are also discussed. A method is provided to assist laboratories, particularly small laboratories, in providing clinicians with an appropriate therapeutic range for the activated partial thromboplastin time, the most commonly used test in monitoring heparin therapy.

Guidelines for organisation and management of external quality assessment using proficiency testing. Expert Panel on Cytometry of the International Council for Standardization in Haematology.

This document is intended to assist towards the WHO objective that external quality assessment (EQA) schemes be established at national and/or regional levels world-wide. Quality assurance is defined as all steps taken by the director of a laboratory to ensure reliability of laboratory results and to increase accuracy, reproducibility and between-laboratory comparability. This includes the use of internal quality control procedures and participation in external quality assessment. Internal quality control provides the means for evaluation of analytic test results at the time of testing in order to decide whether they are reliable enough to be released to the requesting clinicians. EQA, on the other hand, refers to a system of retrospective and objective comparison of results from different laboratories by means of proficiency testing (PT) organised by an external agency. The main purpose is to establish between-laboratory and between-method (including between-instrument) comparability, and agreement with a reference standard where one exists. Internal quality control and EQA complement each other and must never be considered as alternatives.

Flow cytometric reticulocyte analysis. Multiinstitutional interlaboratory correlation study.

Reticulocyte analysis by flow cytometry offers precision and sensitivity greater than those of conventional morphologic methods and permits derivation of a reticulocyte maturity index. However, interlaboratory variability has not yet been reported. The authors analyzed 310 samples at eight sites using 11 instruments over a 4-month period to examine intermethod and interlaboratory variabilities. Stains included thiazole orange, ethidium bromide, and auramine O. Instruments included models by Coulter, Becton Dickinson, TOA Medical Electronics, and Ortho Diagnostics. The coefficient of variation (CV) among all sites and methods on these samples varied as a function of the reticulocyte percentage, ranging from a mean CV of 69% for samples with < .5% reticulocytes to 24.1% for those with > 2.5% reticulocytes. The best performance was observed with the TOA R-1000 dedicated reticulocyte analyzers, with a mean CV of 18.4% for samples with < .5% reticulocytes and 4.6% for samples with > 2.5% reticulocytes. The reticulocyte maturity index showed comparable intersite precision, with a mean CV of 16% for samples with > 2.5% reticulocytes with multipurpose flow cytometers and a mean CV of 7.3% with the TOA R-1000 instruments. Interclass correlations among all sites ranged from .79 to .99 for the reticulocyte counts and .41 to .88 for the reticulocyte maturity index. The authors conclude that flow cytometric reticulocyte analysis is more precise than manual reticulocyte analysis. With greater automation of this methodology, further interlaboratory standardization of reticulocyte counts and the reticulocyte maturity index can be achieved.

A method to examine the need for duplicate testing of common coagulation tests.

A statistical protocol for evaluating the need for duplicate coagulation testing was developed. It requires at least 32 sets of duplicate prothrombin times or partial thromboplastin times over the expected range of results. In addition to the statistical procedures, clinical evaluation of the duplicates is required.

Fitting the cell counter to the bed count.

This article has delineated and discussed information pertinent to the choice of hematology instruments. The choice may be easy or difficult depending on the individual circumstances. Many good instruments are available to clinical laboratories. The critical point is to get the best possible match of the workload with the instrument so that the highest quality of blood counts can be produced at the lowest possible cost. And this may not be an easy task.

Molecular marker test standardization.

A review of the status of standardization of laboratory tests of particular interest to oncologists is presented. Currently, relatively few of these tests are standardized; as a result, interlaboratory and interinstitutional comparison of data is problematic. In 1992, additional interlaboratory studies of common tumor markers will be initiated by the College of American Pathologists. The National Committee for Clinical Laboratory Standards also has begun to develop standard methods and guidelines for these important tests.

A method for the preparation of methaemoglobin-containing human red cell suspensions.

The variables affecting the formation and stability of intracellular methaemoglobin were examined. A method is proposed for the preparation of intracellular methaemoglobin specimens.

Effects of cell membrane disruption on the relaxation rates of blood and clot with various methemoglobin concentrations.

The magnetic resonance imaging (MRI) characteristics of hemorrhage and clotted blood change with age. The effects of methemoglobin and cell membrane lysis, factors which in part may underlie this evolution of imaging characteristics, were studied using clotted and heparinized dog blood at various methemoglobin concentrations. Cell lysis did not alter the longitudinal relaxation rate (1/T1) in clotted or unclotted samples. Membrane lysis altered significantly the transverse relaxation rate (1/T2) in both clotted and unclotted samples. Lysed samples of oxygenated blood at 0% methemoglobin had significantly higher T2 values than intact samples. At 0% methemoglobin, clotted samples had slightly but significantly shorter relaxation times than unclotted samples. Within the samples studied, large changes in the state of oxygenation and methemoglobin content were observed in less than 24 h. Such changes necessitate frequent monitoring of these parameters if serial studies are to be done.

The process of quality assurance. Quality indicators in clinical pathology.

The process of developing and using indicators of quality performance in laboratory medicine presents significant problems for clinical pathologists. Although there have been many proposed indicators, many fail to provide meaningful information. Four types of quality indicators (data reliability, laboratory management, clinical utilization, and pathologist credentialing) are proposed and examples of their use are given.

Future directions for quality assurance in laboratory haematology.

Seven recommendations for the future in haematology quality assurance have been made. They include two levels of control cells, expanded rules for quality control of analysers, continued development of random error detection systems, performance goals for instruments, improved MCV calibration, appropriate checklist items and blood-film evaluation methods.