Performing a fingerstick: what can affect the results?
Due to PLT adhesion to tissue and capillary walls and imprecision in preparation and blood draw procedures, discrepancies between capillary and venous blood values might occur for some parameters. For example, platelets might be 5%–10% lower in capillary blood and PLT clumping can affect the lymphocyte count, resulting in falsely elevated white blood cells.
Swelab Alfa Plus and Medonic M32 are equipped with a high-precision shear valve that provides an absolute volume for the cell count from the open tube, cap piercing, and pre-dilute inlets. As the MPA inlet bypasses the shear valve, it is of utmost importance to ensure correct volume is drawn by making sure the whole capillary is filled with blood and by wiping of any excess blood outside of the capillary before sliding it into the MPA module.