Lamellar body counts: A consensus on protocol

Lamellar bodies, concentrically layered "packages" of phospholipid that rep resent the storage form of surfactant, can be counted in the platelet chann el of most electronic cell counters. The lamellar body count has been used for more than a decade and performs as well as traditional phospholipid ana lysis as an assay for evaluating fetal lung maturity. It is preferable to p hospholipid analysis because it is rapid, objective, and inexpensive and ca n be performed in any hospital laboratory. The current methodologies for sp ecimen preparation vary widely among laboratories, most notably with respec t to centrifugation, resulting in differences in maturity cutoffs used. Our goal was to establish a consensus regarding a standardized methodology for the lamellar body count. Institutions that previously had published their results with lamellar body counts were invited to contribute. The consensus of the four participating institutions includes the following: centrifugat ion is not a necessary step and should be abandoned, maturity is suggested by a count of 50,000/muL or greater, and immaturity is suggested by a count of 15,000/muL or lower. As the lamellar body count gains wider acceptance as a primary assay for assessing fetal lung maturity, the test must be perf ormed uniformly and accurately, given the implications of acting on a false ly negative test resulting from improper methodology. (Obstet Gynecol 2001; 97:318-20. (C) 2001 by The American College of Obstetricians and Gynecologi sts.).