Preanalytical phase in pleural fluid analysis

: The total testing process for pleural fluid samples comprises a continuum of five phases, from the initial procedures of the pre-preanalytical phase to the final steps in the post-postanalytical phase. It can be assumed that the extra-analytical phases in laboratory testing of pleural fluid samples are equally susceptible to errors and that the error rate is comparable to (or even higher than) the corresponding phases in standard samples analysis. It is through harmonization of the preanalytical phase that the risk of errors might be reduced and patients’ safety improved. However, with the exception of a few documents from standard writing bodies and national societies, little evidence is available on harmonization of the preanalytical phase for pleural fluid testing. A thorough understanding of potential errors in the preanalytical phase of pleural fluid analysis enables laboratory professionals to ensure reliable testing results and to assist clinicians in the diagnostic evaluation of pleural effusion. In this review, we discuss the preanalytical phase of pleural fluid analysis, presenting variables potentially affecting the quality of pleural fluid samples and hence the analytical reliability of pleural fluid analysis.