Lamellar body count in amniotic fluid: a comparative study of four different hematology analyzers.

Abstract

The accurate antenatal prediction of fetal lung maturity (FLM) based on results from amniotic fluid samples is of utmost importance in the prevention of neonatal respiratory distress syndrome and its complications. The current “gold standard” for the determination of FLM is the evaluation of phospholipids (i.e., measurement of lecithin/sphingomyelin ratio and quantification of phosphatidylglycerol) in amniotic fluid samples by thin-layer chromatography. These tests are, however, time-consuming and not continuously available at most institutions. Lamellar bodies are lamellated phospholipids that represent a storage form of surfactant (1). Because lamellar body diameter (range, 1–5 μm) is similar to that of small platelets, lamellar body counts (LBCs) can be obtained rapidly with use of the platelet channel of a hematology analyzer (2). Recently, a consensus LBC protocol was published, and a FLM cutoff of 50 000/μL was suggested without discussion regarding the hematology analyzer used (3). The majority of published reports to date have used a Coulter brand of hematology analyzer to establish clinical decision limits (2)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). The published experience with other hematology analyzers, such as the Sysmex NE-1500 (14), for obtaining LBCs is limited. One study used LBCs from three different analyzers (two from Coulter, one from Sysmex) to assess FLM without providing any evidence that the instrumentation was not a source of imprecision (9). Our objective was therefore to compare LBC concordance from the following four hematology analyzers: Coulter Gen-S (Beckman Coulter), Sysmex XE-2100 (Sysmex), Cell-dyn 3500 (Abbott Laboratories), and ADVIA 120 (Bayer Corporation). Leftover amniotic fluid samples sent to the Barnes-Jewish …