Lamellar body count in amniotic fluid as a rapid screening test for fetal lung maturity.

We conducted a 2-year prospective clinical outcome study to evaluate the usefulness of amniotic fluid lamellar body count (LBC) as a screening test for fetal lung maturity. During the interval under study, outcomes of 170 neonates were used to evaluate the test; 14 neonates had respiratory distress syndrome (RDS). Both LBC and lecithin-sphingomyelin ratio (L/S ratio) test results were available in 129 cases. All the cases of RDS had LBC of 50,000/microliter or less and L/S ratio of 2.8 or less; 72.7% of cases with no RDS had LBC greater than 50,000/microliter, and 80.4% of normal cases had L/S ratio higher than 2.8. LBC test results showed good correlation with L/S ratio test results between 26 weeks and 33 weeks of gestation (r = 0.78, p < 0.0001). With the cutoff value of 50,000/microliter for LBC, the diagnostic sensitivity and specificity were 100% and 80%, respectively. Determining LBC by cell counter is justified as a useful rapid initial screening test for the assessment of fetal lung maturity.