Quality Control In Haematology - Sysmex

SEED HematologySysmex Educational Enhancement and DevelopmentNo 2 2017Quality Control in HaematologyQuality control materials: the better you treat them, the more you can trust your haematology resultsKey words:Quality controls, quality materials, controls, internal quality controlWhy is Quality Control so important?IQC is conducted by running one or more control materialsOne vital part of quality assurance is the internal qualityon the analysis system that is to be checked. The controlcontrol (IQC), which is used to ensure day-to-daymaterials undergo an analytical procedure identical to thatconsistency of an analytical process, helping to determineapplied to patient samples. The results are plotted onwhether patient results are reliable enough to be released.control charts as described by Levey-Jennings, and thosePerforming IQC also enables the laboratory to monitor andcharts are interpreted in the usual fashion.document the quality of its work. In most of the countries itis required to perform IQC by national regulations.Sounds simple? Well, it’s not entirely simple. There arefactors that need careful consideration if the IQC system isThere are four main purposes of IQC:to represent a lab’s routine analytical operation adequately.1. To monitor the complete analytical process.2. To detect immediate errors that occur due toRequirements QC materials have to meeta) a failure of the analytical system,Controls are materials that contain an established amountb) adverse environmental conditions, orof the substance to be tested. Controls have to be tested atc) operator performance; for example maintenancethe same time period and in the same way as patientprocedures being carried out incorrectly3. To monitor the long-term test performance that may besamples. The purpose of the control is to validate thereliability of the analysis system and to evaluate operatorinfluenced by changes in the performance of theperformance and environmental conditions that might havea) analytical system,an impact on the results. It is particularly critical to selectb) environmental conditions andappropriate control materials.c) inter-operator variance.4. To provide proof of an adequate long-term quality leveland to comply with regulatory requirements.

Sysmex Educational Enhancement and DevelopmentSEED Hematology No 2 20172The best materials for IQC are typical samples of the routinecomponents that simulate cells, such as latex particles.test materials, assuming that they are sufficiently stable forHowever, a microscopic white blood cell differential cannotthe purpose. Table 1 lists recommended properties of qualitybe accomplished with this material, as the white blood cellscontrol materials as per recommendations of the Hong Konghave been treated to enhance their stability. This meansAssociation of Medical Laboratories (HKAML) [1].they will not stain to demonstrate the typical cellmorphology known from May-Gruenwald-Giemsa staining.Additionally, it has to be taken into consideration thatBut regarding lysing and staining behaviour with thecontrol materials need to be different from calibratoranalyser reagents, the stabilised cells only show smallmaterials [2].differences to fresh blood cells. These differences are thereason why the analyser uses a QC mode to produce andTable 1 Recommended properties of a QC material1.It should resemble a human sample (blood, plasma, Serum,CFS, etc).2.The analyte concentration should be at medically significantlevels. It should span the clinically important range of ananalyte’s concentrationdisplay the measurement results.Sysmex control materials are ready to use. All controls aredelivered in vials with sufficient material for the controlperiod and are measured with the same measuringprinciple as patient samples.3.The material matrix should be as much like human sample aspossible4.Constituents should be stable for a long period of time5.After the vial has been opened and material prepared itshould be stabile during the period of use6.The control material should be ready to use and requireminimal preparation7.Convenient sizes of aliquots/vials can be prepared and vialto-vial variability should be lowFor the manufacturing of our haematology control8.It should be reasonable priced ( optional)(Nebraska, USA), who is recognised worldwide as the leader9.The control material should be tested in the same manner aspatient samplesin cell stabilisation. Streck’s core competence is theFor all diagnostic whole blood parameters Sysmex deliverscontrols in the low, normal and high analytical range and inorder to check body fluid parameters, we provide twocontrol levels.materials, we trust the well-known producer Streck Inc.development of quality control materials that are tailoredto the customers’ needs.QC materials from SysmexManufacturing quality control materials for haematology isTransportation, storage conditions and shelf lifea challenge compared with controls for clinical chemistry ifSysmex haematology control materials are to be storedall the points mentioned above are to be covered. Nativewith a closed cap at 2 – 8 C. A short-term increase incells naturally have a very limited survival rate. To extend atemperature, which may occur during transportation, doescell’s life to a longer period, efficient stabilisation is needed.not affect the quality of the product. All haematologyDue to this, haematology quality control material iscontrol materials must be protected from freezing. Whendifferent from freshly collected patient samples. This meanshandled in this manner, the products are guaranteed stablecare must be taken to ensure the material has been useduntil the expiration date stated on the package and vials.correctly when interpreting quality control results.Once the vials have been opened or sampled by cappiercing, they will retain stability – depending on theSysmex control materials include stabilised human red bloodcells (RBC), white blood cells (WBC), and a platelet (PLT) andnucleated red blood cell (NRBC) component in apreservative medium. They are free from any artificialproduct type – as stated in Table 2.

Sysmex Educational Enhancement and DevelopmentSEED Hematology No 2 20173Table 2 Stability of Sysmex haematology controlsControl materialPeriod of useOpen vial stabilityEightcheck-3WP84 days7 dayse-Check (XS)56 days14 dayse-Check (XE)56 days7 daysXN-L Check84 days15 daysXN Check56 days7 daysXN-L Check BF56 days30 daysPreparation of XN-Class QC materials beforemeasurementWhen storing and preparing quality control materials it isimportant to carefully adhere to the manufacturer’sinstructions for storage and equilibrating.1. Remove the vial from the refrigerator and equilibrate withroom temperature (15 – 30 C) for at least 15 minutesbefore use.2. Roll each vial between the palms of your hands for 15seconds (see Fig. 1).3. Holding the vial from end to end between the thumb andforefinger, invert the vial 20 times using a very quickturning motion of your wrist during mixing. Details can beseen in a video on the CD-ROM or USB stickaccompanying each QC lot (see Fig. 2).Fig. 2 Invert the vial 20 times holding it from end to end,using a very quick turning motion of your wrist duringmixing.4. Analyse the QC material on the instrument according tothe Instructions for Use. The pierceable septum in the vialcap allows sampler analysis.5. Subsequent analyses during this test period may beperformed by inverting the vial 5 times prior toinstrument analysis.6. Return the vial to the refrigerator (2 – 8 C) for storageYou can also watch a movie about the mixing of thequality control vials on our sysmex-qcmaterial-preparation-26847.htmlA simple procedure with a great impactWhen the result of a QC measurement falls outside itslimits, analysis should be stopped, patient results held, andthe analysis system investigated. As soon as error sourceshave been identified and corrections made, themeasurement of control material should be repeated. If theFig. 1 Roll the QC vial for 15 seconds between the palms ofyour hands.

Sysmex Educational Enhancement and DevelopmentSEED Hematology No 2 20174results read correctly, then patient samples (thoseIncorrect mixing and its effectsfrom the period of the last correct QC measurementIdentifying mixing problems is generally difficult asuntil the QC error has been discovered and solved),it depends on both the intensity and duration ofalong with another quality control specimen, shouldmixing. However, taking a closer look at the twobe repeated. Do not simply repeat the testingextremes (insufficient vs. overmixing) reveals thatwithout looking for sources of error and takingnumerical results of WBC, RBC and PLT can becorrective action.distorted due to the use of an incorrect mixingprocedure.According to the World Health Organisation (WHO),possible problems to consider include [3]:An overmixed sample is generally more difficult toidentify and occurs more rarely. If the sample isnDegradation of reagents or kitsmixed for too long a time with high speed, slightlynControl material degradationelevated WBC counts together with markedlynOperator errorincreased PLT counts can be observed. Never mixnFailure to follow manufacturer’s instructionsthe haematology QC vials on an automated roller ornAn outdated procedure manualmixing device!nEquipment failurenCalibration errorIn contrast to that, samples that are not mixedsufficiently can be identified by markedly increasedIn haematology it can be generally observed that aRBC counts and related parameters (HGB, HCT) andlot of problematic QC results derive from incorrectdecreased WBC counts and low counts of PLT-Ihandling or inappropriate storage of the material.especially in Level 1 with increased coefficient ofAlso using outdated materials or vials with too littlevariation (CV) values. Table 3 compares the resultsremaining volume leads to erroneous results.of improperly mixed QC samples.Particular in haematology, controls deserve accuratetreatment before measurement as they containblood cells that need to be homogenized beforemeasurement.Below, some examples are shown where the resultshave been out of their range due to mistreatment ofTable 3: Results of improperly mixed QC samplesNot mixedOvermixedWBC WBC ( )RBC, HGB, HCT RBC, HGB, HCT notmarkedly influencedPLT-I PLT-I Aspirated from thesediment, more red bloodcells are measured, butwhite cells areunderrepresented ormissingRed blood cells aredestroyed and fall by sizeinto the PLT area, wherethey are then counted aslatelets.the QC material. Changes in the numerical results,particularly of the complete blood count (CBC) andreticulocyte parameters, can be observed. Checkingthe cell distributions in histograms and scattergramscan also help to reveal differences to resultsobtained from correctly treated material.Measurement examples and scattergram images ofall control levels can be found on the CD-ROM orUSB stick that always accompanies the QC materialfor comparison purposes.