Quality specification in haematology: the automated blood cell count.

BACKGROUND

Quality specifications for automated blood cell counts include topics that go beyond the traditional analytic stage (imprecision, inaccuracy, quality control) and extend to pre- and post-analytic phases.

METHODS

In this review pre-analytic aspects concerning the choice of anticoagulants, maximum conservation times and differences between storage at room temperature or at 4 degrees C are considered. For the analytic phase, goals for imprecision and bias obtained with various approaches (ratio to biologic variation, state of the art, specific clinical situations) are evaluated. For the post-analytic phase, medical review criteria (algorithm, decision limit and delta check) and the structure of the report (general part and comments), which constitutes the formal act through which a laboratory communicates with clinicians, are considered.

RESULTS

K2EDTA is considered the anticoagulant of choice for automated cell counts. Regarding storage, specimens should be analyzed as soon as possible. Storage at 4 degrees C may stabilize specimens from 24 to 72 h when complete blood count (CBC) and differential leucocyte count (DLC) is performed. For precision, analytical goals based on the state of the art are acceptable while for bias this is satisfactory only for some parameters.

CONCLUSIONS

In haematology quality specifications for pre- and analytical phases are important, but the review criteria and the quality of the report play a central role in assuring a definite clinical value.