Standards of Laboratory Practice: Evaluation of Fetal Lung Maturity (Nacb Symposium‪)‬

This document provides guidelines to laboratories involved in evaluating fetal lung maturity (FLM) for the prevention of respiratory distress syndrome (RDS). [1] Patient populations can vary significantly across differing healthcare centers. This variation affects the requirements for turnaround time and test predictability, and therefore the selection of the "best" method is dependent on the healthcare setting. Methods that work well in low-risk full-term pregnancies often perform poorly when used in high-risk preterm pregnancies. The guidelines include preanalytical considerations (sample collection, condition, and handling), analytical approaches (techniques, turn around time, sample requirements, effect of contamination), and interpretation of results (reference intervals, prediction of fetal lung status, effect of differing patient populations). I review lecithin/ sphingomyelin (L/S) ratio [1, 2], fluorescence polarization (FP) [3-6], phosphatidyl-glycerol (PG) [7], foam stability index (FSI) [8], and lamellar body counts (LBC) [9-11]. I have purposefully avoided tests that do not measure pulmonary surfactant (e.g., creatinine, lipid-staining cells) and those novel tests that, while promising, do not have a broad enough acceptance or enough prospective studies to yet justify their recommendation (e.g., refractive index-matched anomalous diffraction [12], nuclear magnetic resonance spectroscopy [13]). Preanalytical Considerations