Past and future approaches to assess the quality of platelets for transfusion

No automated test exists to routinely measure platelet quality. Currently, the short, 5-day shelf life of platelet concentrates is largely dictated by the risk associated with bacterial contamination and not by platelet quality. With the implementation of bacterial testing and pathogen inactivation, platelet quality will become the major determinant for the shelf life of platelet concentrates. However, extended use of platelet concentrates stored beyond 5 days will require quality testing. In addition, high platelet quality would be expected to result in improved clinical efficacy, determined by count increment, improved hemostasis, and lower risk for adverse reactions in recipients. No in vitro quality test has yet demonstrated a good correlation with clinical efficacy or improved hemostasis. This review focuses on those tests of platelet quality that are based on platelet morphology. These include visual inspection of swirling, microscopic morphology score, measurement of light transmission through platelet concentrates, and platelet light scattering techniques. Recently, a new test for platelet quality has been introduced that uses dynamic light scattering. The advantages and remaining challenges for dynamic light scattering before it can become a routine platelet quality test are discussed.