EVALUATION OF LAMELLAR BODY NUMBER DENSITY AS THE INITIAL ASSESSMENT IN A FETAL LUNG MATURITY TEST CASCADE

The objective of this study was to assess the sensitivity and specific ity of lamellar body number density in the prenatal prediction of the respiratory distress syndrome. Seventy consecutive amniotic fluid spec imens obtained by amniocentesis within 72 hours of delivery were asses sed for lamellar body number density, optical absorbance at 650 nm, le cithin/sphingomyelin ratio and phosphatidylglycerol. A maturity criter ion of greater than or equal to 46,000/ mu L for lamellar body number density yielded values for diagnostic sensitivity of 100% (7/7), speci ficity of 89% (49/55), positive predictive value of 54% (7/13) and neg ative predictive value of 100% (49/49). These values were also determi ned for the other analytes, with results similar to those reported els ewhere. Lamellar body number density is an effective and inexpensive f irst test for the rapid identification of the fetus at high risk for t he respiratory distress syndrome. A cascade approach, using lamellar b ody number density as the first test and optical absorbance at 650 nm as the second test, improves the predictive value as compared to any s ingle test of fetal lung maturity.