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Preanalytics Guidelines

Since it has been documented in many studies that approximately 60% of laboratory errors arises from non-conformities related to the pre-analytical stage (e.g. mislabeling, sample collection, preparation of patient prior testing and inaccurate information provided related to patient’s demography) therefore, the instruction below is intended to clarify and assure the acceptance of the collected samples from patients for laboratory analysis.

To comply with patient’s international safety goal, it is always mandatory to confirm the identity of the patient prior to collecting their sample (this can be done by simply asking the patient their name prior to preparing them for the sample extraction).

  1. Request Form 
    • Patient details: 
      Please enter all data of the patient on the Request Form legibly. Gender & Age/Date of Birth are crucial due to different reference ranges based on gender and age. Please enter the CLINIC name on the space provided. 
    • Test/Analysis requested: 
      Please enter the test(s) required, type of sample, and storage
  2. Tubes / container labeling 
    • Using the sticker provided with serial number, please label the test tubes / sample container properly with the details of the patient corresponding to its request form with: Patient name and Gender to ensure correct identification (These makes a total of 3 identifier: Serial number, Patient name, Gender).
    • Check the sample types required for the analysis of interest. This is easily identified on the request form by the colored abbreviations on the side of each test. Kindly check if the test needs any special precaution (light sensitive, immediate freezing is required, etc.).
    • Please refer to the chart for the order of tubes to be used for multiple blood sample extraction. It is important to follow the order of blood draw to avoid contamination with additives from the previous blood collection tube.
  3. Patient Preparation / Instruction
    • Please ensure that the patient has been instructed properly prior collection of sample: fasting (for certain test required), or how to collect certain samples such as 24 hour Urine collection, Semen analysis, Stool analysis, Urine analysis, Sputum analysis, etc.
    • Patient should be rested, seated / lying comfortably, 5 – 10 minutes prior blood extraction.  This is important for certain tests to avoid false elevated results (e.g  Creatine Kinase-CK Total)
  4. Hemolysis: 
    Prolonged/strong application of tourniquet during blood collection cause venous congestion which could lead to hemolysis (This will interfere with significant number of test results). 
    Ideally, tourniquet should be loosen in less than 30 seconds (after the needle has inserted) and not more than 1 minute.
  5. Sample volume:
    • It is essential to fill up the vacutainers containing citrate for coagulation and ESR parameters to the mark on the tube (No more, no less) due to standardized dilution.
    • Please ensure to provide the sample volume needed for each requested analysis.
  6. Clotted blood in anti-coagulated tubes such as: EDTA, Citrate, Heparin, NaF, etc.
    Tubes which contain anticoagulants must be mixed by INVERTION technique (five times) after blood collection to have a homogenous mixture of blood and anticoagulant to prevent sample from clotting.
  7. Vacutainers/Clotted sample: 
    To obtain serum, whole blood samples should be left standing in room temperature for 20 – 30 minutes prior to centrifugation in order to allow for a complete clotting of the sample. Ideal speed of centrifugation is 3,000 rpm for 10 minutes. If the final clotting process is not achieved and you centrifuge the sample, further clotting occurs in the separated sample. If this is not recognized by the technician (as small clots can be overseen), wrong values may result as a consequence.
  8. Coagulation parameters: 
    Storage of samples for more than 4 hours for Coagulation test parameters could lead to increased clotting time or decreased activities. Hence, it is highly suggested that the sample should be sent out as soon as possible and separate the citrated plasma  immediately.
  9. CBC’s: 
    Blood differential count samples, (manual or automated) should not be kept for more than 4 hours. The blood cells starts to deteriorate (shrink or burst) leading to significant changes in morphology.
  10. Split samples: 
    Splitting of samples can lead to patient sample confusion in the clinics. It is always recommended to conduct the test from the primary tube to avoid and confusion and eliminate any dispensing and labeling errors.
  11. Vial Leakage: 
    Please ensure to keep the sample safe from leakage. Securely screw the cap or double seal the container using
    parafilm. Leaking vials are hazardous for personnel including non-medical staff, like drivers and receptionists. Kindly use closed systems as provided by YDL.
  12. Stapling of bags: 
    Stapling of bags is not advisable. Kindly use the adhesive flap to seal the pouches.
  13. Microbiology/ sensitive germs: (Gonococci, Chlamydia, Mycoplasma, Meningococci, and Anaerobic Germs). 
    Long storage of samples leads to damage of sensitive germs such as gram negative diplococci, Chlamydia and others. Please avoid long storage. We recommend calling us in such cases in order to provide the adequate collection material (special swabs etc.).
  14. HVS samples: 
    We recommend WET SWAB with transport media.
  15. Chlamydia PCR: 
    Please send concentrated first morning urine or use special dry swabs (due to inhibiting substances for PCR reactions in normal collection material). Let it dry for 3 hours (contamination free area) and send it to the Laboratory in a sterile container without additives.
  16. Blood PCR HCV/HBV and others: 
    Please do not open the vacutainers (or split samples) designated for PCR analyses.
    The probability of sample contamination is very high in central laboratory units (as designated PCR room is required).
  17. Storage and Transport: 
    Please ensure to follow the appropriate storage of sample as per requirement of the test (Ambient/Cold/Frozen).