Total WBC count and differential WBC count HemoCue WBC DIFF system

Transcription

1 TLM_PRO_029 and Version No. 001 Page 1 of 6 Department: Clinical Sciences Unit: Tropical Laboratory Medicine Total WBC count and differential WBC count HemoCue WBC DIFF system Project/study: Not applicable 1. Scope and application This document provides instructions to ensure safe and accurate total WBC and differential WBC count determination using the HemoCue WBC DIFF system. This procedure describes the different steps to obtain the result. The device can be used in primary health care, in clinical trials, as a point-of-care testing device, etc. 2. Responsibilities Function Activities Lab Technician complies with this procedure keeps a record of all the data (direct print-out, transfer to pc, in lab note book) follows the Quality Assurance regulations and keeps a record of all the quality controls applies the maintenance procedures informs the lab manager when there is a problem with the device Lab Quality Manager checks that the internal quality procedures are followed correctly ensures that the quality control data is properly recorded subscribes the laboratory in an external quality program in order to evaluate the quality of the lab data Lab Manager checks that the lab technicians follow the procedure checks that maintenance is done at the right time takes action when reparation is needed formulates a maintenance contract with the supplier checks that data is properly recorded supervises the lab quality manager 3. References HemoCue WBC DIFF User Manual Osei-Bimpong A, et al. Point-of-care method for total white cell count: an evaluation of the HemoCue WBC device. Int Jnl Lab Hem 2009;31: De Jonge R. Evaluation of the HemoCue WBC analyzer to count leucocytes in body fluids. Ned Tijdschr Klin Chem Labgeneesk 2011;36: HemoCue WBC DIFF User Manual 4. Procedures 4.1 Principle of the test The red blood cells are lysed in the cuvette and the nuclei of the white cells are stained. 37 images are taken of the stained white cells and the cells are identified. The number of cells are counted by image analysis in the analyzer. 4.2 Safety All blood samples are potentially infectious. Follow standard safety precautions.

2 TLM_PRO_029 and Version No. 001 Page 2 of Specimen Special conditions for patient preparation: none Type of sample: capillary (finger stick) or anticoagulated venous blood (EDTA in solid form). Volume of sample: 10 µl of whole blood Sterility: not needed Time between collection and measurement: o o capillary: immediately venous: Store the samples at room temperature (15-35 C). Analyze them within 8 hours of sample taking. Rejection criteria: o blood samples with clots o cold agglutination or cyroglobulin o blood samples not or incorrectly labeled 4.4 Equipment and reagents HemoCue WBC DIFF analyzer HemoCue WBC DIFF or HemoCue WBC microcuvettes 6 type C batteries(1.5 V) and/or mains adapter Non sterile, single use gloves Tissue or gauze Alcohol swabs, sterile lancets Venous blood collection set (needles, syringe, sample tubes) R&D Systems HemoCue WBC control solutions WBC DIFF cleaner swab Pipette Parafilm or glass slide 4.5 Procedure Check the expiry date of the cuvettes. If expired, do NOT use the cuvettes. Take a new batch of cuvettes that are not expired. Pull out the cuvette holder into the loading position. Switch the machine on: Press and hold left button. The display is activated. Optronic unit is automatically checked: an hourglass is shown on the display The menu is displayed The analyzer is ready for use. You can use a keyboard and/or a barcode reader to insert patient data If you push the right button, you can adapt the settings of the analyzer (check operating manual): o language o time o date o the information you want to display on the result window/in the memory: patient/operator/lab/site/control ID o the units (10 9 /L and/or %) o sound signal o pin code

3 TLM_PRO_029 and Version No. 001 Page 3 of 6 Push the second button patient test and insert the required data (patient/operator/lab/site ID) with the keyboard or the barcode reader. Push the right button to confirm the inserted data If you want to change the data, push the left button until the required window is displayed The symbol insert cuvette is displayed Take a patient sample: o For fingerstick blood: Clean the fingertip with 70% alcohol and allow to dry Puncture the fingertip (middle or ring finger) with a sterile lancet Wipe away first 2-3 drops of blood Fill the microcuvette in one continuous process. The correct amount of blood (10 µl) is drawn into the microcuvette. The microcuvette should be completely filled. Do NOT refill!! o For venous blood/control: Mix the sample well (invert times by hand or place for 1-2 min on roller mixer) Place a drop of blood onto a hydrophobic surface (e.g. parafilm) or glass slide, using a pipette. Fill the microcuvette in one continuous process. The correct amount of blood (10 µl) is drawn into the microcuvette. The microcuvette should be completely filled. Do NOT refill!! Wipe away any excess of blood on the outside of the microcuvette tip Check for air bubbles in the filled microcuvette. If present, use a new microcuvette. Place the filled microcuvette into the cuvette holder and push the holder gently back into the measuring position (within 40 seconds after filling the cuvette).

4 TLM_PRO_029 and Version No. 001 Page 4 of 6 The window measuring is displayed. After 5 minutes the results will be displayed: o the WBC DIFF result window (when using the WBC DIFF microcuvettes) o the WBC result window (when using the WBC microcuvettes) o the inserted data Push the second button to switch between the different windows. Read and record the result. Push the third or the first button to accept or refuse the result. The result is stored, refused results are also stored but are marked with a flag. You can now print out the result. The menu is displayed again. Remove and discard the microcuvette in the appropriate bio-hazard container. Push the cuvette holder back into the instrument. Don t measure the filled cuvette again. All results are stored in the analyzer (up to 600 results). You can view them on the display, print them out (immediately after each measurement) or transfer them to a computer (special software required). You can manually remove the results from the memory. (check the operating manual) 4.6 Quality control The analyzer has an internal electronic self-test, to check the optronic unit. This test is performed every time the analyzer is switched on and before every measurement. A daily quality control has to be done with the recommended controls: R&D Systems HemoCue WBC control Push the left button on the menu (QC-test), confirm, insert the required data and run the test (check operation manual).the QC data are stored in the memory (check operating manual) 4.7 Reporting results In 10 9 /L and/or % Measuring range: x10 9 /L. Higher results are reported as HHH, lower results as LLL. Differential counts are displayed when WBC count is within 1-30 x10 9 /L range. The normal ranges are: (depending on sex, daily variation, indigestion, stress, smoking, fitness)

5 TLM_PRO_029 and Version No. 001 Page 5 of 6 Children (mean ± 2SD) 3-6 months 1 year 2-6 years 6-12 years WBC count x 10 9 /L 12 ± 6 11 ± 5 10 ± 5 9 ± 4 Neutrophils x10 9 /L Lymphocytes x 10 9 /L Monocytes x 10 9 /L Eosinophils x 10 9 /L Adults (mean ± 2SD) 4.8 Storage and stability Adult Adult % WBC count x 10 9 /L Neutrophils x10 9 /L Lymphocytes x 10 9 /L Monocytes x 10 9 /L Eosinophils x 10 9 /L Basophils x 10 9 /L <1-2 Use the microcuvettes before the expiry date. Store the microcuvettes at C, < 90% non-condensing relative humidity. Do NOT refrigerate. An unopened capsule of microcuvettes can be stored for 4 weeks between 4 C - 50 C. Write down the date of opening on the vial. Allow the microcuvettes to reach C before use. Once the wrapping of a single package microcuvette is opened, it has to be used within 10 minutes. Store the analyzer at 4-50 C. Operate the analyzer at C,< 90% non-condensing relative humidity. 4.9 Maintenance Check that the analyzer is turned off Clean the cuvette holder every day with alcohol or mild detergent (check operating manual) Wait for 15 minutes before replacing the cuvette holder. Remove the cuvette holder to clean the optical unit with the WBC DIFF cleaner swab. (check operating manual) Wait for 15 minutes. Replace the cuvette holder. Clean the cover of the analyzer with alcohol or mild detergent 4.10 Causes of error Insufficient or non-uniform filling of the microcuvette (Rouleaux or agglutination): repeat the test. Presence of air bubbles in the microcuvette Incorrect mixing of the venous blood Excessive squeezing of the finger when collecting capillary blood Troubleshooting: (see operating manual for more troubleshooting)

6 TLM_PRO_029 and Version No. 001 Page 6 of 6 5. Records and archives Appendices & Forms for completion Number Title Not applicable - Revision Changes with respect to the previous version Initial version Name and function Date Signature Author Barbara Barbé 01/02/2012 Reviewed by An Vermaelen Approved by Jan Jacobs