The tap test: a rapid indicator of fetal pulmonary maturity.

We present here a new means to assess fetal pulmonary maturity called the tap test. It is rapid, inexpensive, and requires only 1 ml of amniotic fluid. The tap test was compared to the phospholipid profile in 88 fetuses, 70 of whom were delivered before term. All fetuses were born within 72 hours after the amniotic fluid specimen was obtained. The test results were correlated to the absence or presence of the neonatal respiratory distress syndrome. When the tap test was evaluated at 2, 5, and 10 minutes, the predictive values for a mature test result were 100%, 98%, and 98%; the predictive values for an immature test result were 43%, 52%, and 58%, respectively. For the phospholipid profile the predictive values for a mature and an immature test result were 98% and 37%. These findings indicate that the ability of the tap test to predict fetal pulmonary maturity is comparable, if not superior, to that of the phospholipid profile.