Introduction
The haematology section of the SKML manages a number of schemes in the field of haematology. These include the quantitative scheme, “haemocytometry” and the qualitative schemes, “haemoglobin variants”, “thrombocyte and leukocyte serology”, “blood group serology” and “blood cell morphology”. The diverse schemes are described briefly below.
Haemocytometry Scheme
- The haemocytometry scheme is suitable for laboratories which carry out analyses on peripheral blood using a haemocytometer.
- Various parameters of the red and white blood cells are determined from the blood samples, as well as thrombocyte concentration.
- The haemocytometry scheme is organised six times per year and there are eight samples sent per survey.
- The eight samples vary in their concentrations of haemoglobin, erythrocytes, leukocytes and thrombocytes.
- The concentration of leukocytes in the samples can vary between 1.0 en 12x 109 /L, the thrombocyte concentration between 20 en 350 x 1012 /L. The time between the blood being drawn at donation until the measurement in the laboratory is maximally 36 hours: interference with the quality of the samples because of time-delay is thereby limited as much as possible.
- The results from the participants are compared with the results from their own apparatus group and with the results from all participants. The variation in results between the150 participants in the last few years has been small, whereby it is now possible to distinguish apparatus groups in the results.
Haemoglobin Variants Scheme
- Sickle cell disease and β-thalassemia are both haemoglobinopathies resulting from autosomal recessive mutations of the HbA gene.
- In The Netherlands there are approximately 180,000 “healthy” carriers of which the ones with slight anaemia are often treated incorrectly. The non-anaemic carrier is often not even recognised, unless there has already been some investigation based on ethnic indication.Due to insufficient prevention approximately 60 children per year are born with sickle cell disease or β-thalassemia to about 250 at-risk couples, who are in fact eligible for preventative investigation. Luckily, these days carriers are diagnosed sooner (pregnancy screening, neonatal screening) and can be given specific advice. It is considered important that clinical chemistry laboratories offer basic diagnostic tests for carriers and also basic carrier analysis for the partner in order to detect at-risk couples as a means of prevention.
- The Hb-variant scheme, meanwhile, has grown from a quality instrument for the recognition of Hb-mutations to a diagnostic test for the sake of prevention.
- As a participant you will receive lyophilized haemolysate from 12 cases per year, which you can analyse in duplicate. The participant provides the result of a diagnosis, determine the risk and necessity of follow-up investigations. The findings are reported in QBase and results are assessed for accuracy. The correct result is provided at the end of the survey. The aim of the scheme is to ensure “state of the art” diagnostics and prevention.
Thrombocyte and Leukocyte Serology Scheme
- This scheme offers the opportunity for the testing of and improvement upon the quality of thrombocyte/leukocyte serology within the various participating laboratories.
- Once a year five human sera, which may or may not contain thrombocyte-specific antibodies (anti Human Platelet Antigens (HPA)) and/or Human Leukocyte Antigens (HLA) antibodies, are distributed.
- The participating laboratories are asked to identify the antibodies using serological investigation and (if possible) to specify the HPA antibodies.
- In addition, in each scheme four blood samples are sent for HPA genotyping.
- Besides the report of results from the various participating laboratories a critical discussion is organised each year.
Blood Group Serology: “basic”, “pregnancy” and “detailed” Schemes
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The blood group serology schemes offer all participating laboratories the opportunity to test the quality of their own blood group serology determinations (blood groups, antibody screenings, antibody identification and cross-matching) and to compare the results with those of reference laboratories.
- There are three different blood group serology schemes:
- the “basic” scheme includes samples for the determination of ABO and Rhesus D blood groups for 2 patients and 2 donors, the screening of the 2 patient samples for the presence of irregular blood group antibodies and for cross-matching.
- The “pregnancy” scheme involves the determination of ABO and Rhesus D blood groups in 2 samples from pregnant women and 1 cord blood sample, and the screening of the samples from the 2 pregnant women for possible presence of irregular blood group antibodies.
- The “detailed” scheme consists of three sera for which, in the event of a positive antibody screen, the specificity of the antibodies are to be determined in accordance with the appropriate guidelines. These sera have previously been assessed for suitability by 3 reference laboratories. The reference values are determined on the basis of the results from the reference laboratories. This latter scheme is only intended for laboratories which carry out antibody identification. Annually, there are three schemes organised for each variant. The results are reported back to the participants, complete with comments and explanations.
Blood Cell Morphology Scheme
- The advent of automated haematology analysers has seen the assessment of a number of cellular characteristics of blood components become significantly automated.
- Most of the haematology analysers offer, in addition to the haemocytometric parameters, 3-cell or 5-cell differentiation of the white cell count and moreover, a qualitative assessment of the red cell count and thrombocytes.
- This functionality has its limitations, especially in cases where there are abnormal cells present. Therefore a manual morphological assessment is still an important instrument in the diagnostic area of the laboratory. Morphological assessment of blood cells is a time and knowledge intensive process, which requires continuous education, and despite which still results in large variations between laboratory personnel.
- The blood cell morphology scheme aims, on the one hand, to improve the quality of morphological assessment from peripheral blood smears in The Netherlands, but also to offer the individual laboratories and participants the chance to compare their own assessments with the results from reference laboratories.
- Annually there are three schemes organised, each scheme consisting of three blood samples.
- These samples are selected from a collection containing both healthy patients and those with haematologic abnormalities.
- In the arrangement of the schemes an even representation of the abnormalities in red and white cell counts is aimed for and the focus lies on the abnormalities which may regularly be encountered in an average laboratory.
- The report contains a combination of the average of the results obtained from the reference laboratories together with a short description of the underlying affliction and the most important morphological characteristics thereof.
