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151: Assessing vaginal amniotic fluid (AF) for lamellar bodies (LB) as a predictor of fetal lung maturity after preterm rupture of membranes (PPROM)

      Objective

      PPROM is a risk factor for cord accident and chorioamnionitis. It is accepted that delivery is justified beyond 34w of gestation. Before 34w, amniocentesis is offered for assessing fetal lung maturity. Aniocentesis is an invasive procedure which harbors a risk of iatrogenic infection and may be difficult in cases of oligohydramnios. The purpose of this study was to validate an alternative non-invasive measurement of LB drawn from a vaginal pool for predicting fetal lung maturity and to set a cutoff for LB concentration above which fetal lung maturity is likely.

      Study Design

      A prospective study was held in which AF specimens were collected from a vaginal pool from pregnant women with PPROM 26-36.6w of gestation. The specimen was processed through a platelet channel of the cellular counter for an LB count. All specimens included were collected within 2d from delivery. The relationship between respiratory distress syndrome (RDS) and LB count was estimated with logistic regression analysis. The ROC curve and the calculation of the area under the curve were determined with intervals of confidence of 95% to establish a threshold value for LB count. Test performance was calculated for sensitivity and specificity.

      Results

      75 adequate specimens were collected. The mean gestational age at delivery was 34w (+/−2.5). 13 neonates (17%) developed RDS. The incidence of RDS was decreased significantly with increasing gestational age (p = 0.02). RDS was less common in neonates delivered vaginally compared with cesarean delivery (p = 0.03). The cutoff for LB/ml of which the specificity was 100% was 28,000 with a sensitivity of 42% (figure 1). A count of 8,000 LB/ml or less predicts RDS with a sensitivity of 98%.

      Conclusion

      Assessing AF from a vaginal pool for LB count can be used to rule out neonatal RDS without the need for invasive tests.