Validity of Amniotic Fluid Lamellar Body Count as a Screening Test for Fetal Lung Maturity

This prospective clinical outcome study was undertaken in Government Kasturba Ghandhi Hospital, Chennai during the period of 2005-2006 among the 100 pregnant women between 28 and 40 weeks of gestation, with the risk factors for RDS, to prove the efficacy of amniotic fluid lamellar body count as a screening test for fetal lung maturity. The various observations are: 1. The demographic factors studied were age, booking status, socio economic status, and gravidity. They showed no statistically significant difference in homogeneity between the LBC 50,000/μl. 2. Mode of delivery did not significantly affect the occurrence of RDS. 3. In this study the incidence of RDS was 18%. In all cases of severe RDS the count was below 50,000/μl. Case fatality rate was 28%. Death due to RDS had occurred only in group of patients who had LBC below 50,000/μl. 4. In this study LBC ranged from 5,000/μl to 2,88,000/μl. LBC correlates well with the gestational age, as the gestational age increase the LBC also increases. 5. In predicting fetal lung maturity, the LBC showed 90% sensitivity, 83% specificity, 96% positive predictive value and 65% negative predictive values which are comparable to many other studies. 6. The sample size and the duration of gestation were inadequate in this study to analyze the effect of LBC in diabetic patients. CONCLUSION: Management of pregnancies at risk for the development of neonatal RDS would be enhanced by a rapid, accurate, and objective test for fetal lung maturity. In most clinical settings, the most important function of a fetal lung maturity test is to predict accurately the absence of RDS. In many studies lamellar body count compares favorably with traditional phospholipids testing and L/S ratio in the prediction of fetal lung maturity. Our data indicates that using a LBC cut off of 50,000/μl to predict fetal lung maturity, the lamellar body count showed 90% sensitivity, 83% specificity, 96% positive predictive value and 65% negative predictive value. The LBC has many advantages over gold standard L/S ratio. LBC is faster, more precise, more objective, inexpensive, requires smaller sample volume and it is not invalidated by the presence of lysed blood or meconium. In addition the instrumentation required for the test is almost universally available, allowing it to be performed in laboratories where L/S ratio or traditional phospholipid analysis is not available. Since LBC is cost effective, can be performed quickly and the efficacy is also acceptable high, LBC may be used as the test of choice in the assessment of fetal lung maturity