1. Puncture Site and Lancing/Incision Device Selection –Determine the appropriate puncture site and lancing/ incision device for the patient and the tests requested. Using the wrong size lancet/incision device may result in excessive squeezing, prolonged or incomplete collection, poor specimen quality (hemolysis, clotting) and possible redraws, as well as injury to the patient (mainly children).
2. Warming the Puncture Site – Warming the site will increase blood flow up to seven times. CLSI guidelines recommend warming the skin puncture site for three – five minutes with a moist towel or commercially available warming device at a temperature no greater than 42°C.
3. Cleaning the Puncture Site – Allow the alcohol to air dry. Performing skin puncture through residual alcohol may be uncomfortable for the patient and cause hemolysis, which can adversely affect test results.
4. Wipe Away the First Drop of Blood – Immediately following skin puncture, platelets aggregate at the puncture site, initiating the clotting process. Without wiping away the platelet plug, bleeding may stop prior to completion of the blood collection. In addition, the first drop of blood contains tissue fluid, which can cause specimen dilution, hemolysis and clotting.
5. Avoid Milking, Scooping or Scraping of the Puncture Site – It is recommended to touch the collector end of the container to the drop of blood. After collecting 2 or 3 drops, the blood will flow down the container wall to the bottom of the tube. Excessive squeezing (milking), scooping and scraping may cause hemolysis and/or tissue fluid contamination of the specimen. Using a “scooping” or scraping motion along the surface of the skin can also result in platelet activation, promoting platelet clumping and clotting.
6. Collect Specimen Quickly – Specimens must be collected quickly to minimize platelet clumping and microclot formation (hematology testing). Specimens also should be collected quickly to avoid exposure to air and light (blood gases and bilirubin testing).
7. Fill to the Correct Fill Volume – Fill containers to the recommended fill volume (if indicated). Underfilled containers will have higher concentrations of additives. Higher concentrations of K2EDTA may cause erroneous results for MCV and red cell indices and cause RBC and WBC morphological artifacts. Consequently, overfilled containers will have lower concentrations of EDTA and may result in clotting.
8. Mix Specimen – Microcollection tubes must be inverted the appropriate number of times to ensure that the blood and anticoagulant are sufficiently mixed. Mixing is essential to prevent the formation of microclots and platelet
clumps, which can cause inaccurate or erroneous test results.