Capillary method for assessment of pulmonary maturity in utero with the use of amniotic fluid.

Eighty-one human amniotic fluid samples of assessment of pulmonary maturity in utero have been studied by means of the capillary method, a simple and rapid test that correlates with the shake test and L/S ratio. With the advancement of gestational age the flow rate of amniotic fluid decreases on cellulose filter paper (Whatman) in the capillary pasteur pipette. Retention time for 20 microliter amniotic fluid of 74 +/- seconds correlates well with the positive shake test and with L/S ratio of 2.0 or greater in normal human pregnancies.