[The tap test in the rapid evaluation of fetal lung maturity]

A new test for the evaluation of fetal lung maturity, called tap test, been recently developed. This rapid, inexpensive, and reliable test is easy to perform and can be used whenever testing for phospholipids are not available. We performed this test in 260 clear samples of amniotic fluid obtained by transabdominal amniocentesis and the results were compared with those of the "shake test". When the "shake test" was positive (n = 156), the tap test was consistent with fetal lung maturity in all cases. When the "shake test" was intermediate or negative (n = 61 and n = 43, respectively), the tap test was consistent with immaturity in only 19.2% of the cases. Fifty-four fetuses were born within 72 hours after the amniocentesis. The "shake test" was positive in 50, intermediate in 3, and negative in 1. In all but one of there cases the tap test was consistent with maturity. The only case of RDS in this series occurred in an infant with immature result. These findings indicate that the tap test is a reliable indicator of fetal pulmonary maturity and probably with a higher specificity than the "shake test".