A new test-combination for the enzymatic determination of fetal lung maturity

Based on the enzymatic method for the determination of lecithins, clinical tested by DIEDRICH and coworkers [1], there is a test-combination available now which is soon to be brought onto the market by the film Boehringer, Mannheim, Germany. Full working instructions are given with the test. The biochemical basis of the method is the decomposition of the lecithins in amniotic fluid--which originate from the fetal lungs--by means of a phospholipase C. In an enzymatic chain reaction the split phosphorylcholine as a parameter of lecithins is determined quantitatively photometrically by consumption of NADH. Measurements are made against a reagents blank and Precilip EL (BOEHRINGER, Mannheim) as a quality control. The test set can be used for some months with a maximum of 30 single determinations. In a double-blind study the enzymatic method was tested against the densitometric determination of lecithins by KYNAST and SALING [2]. The examination of 39 amniotic fluid samples which were won by amniocentesis at about the 30th to 42nd week of gestation showed a highly significant relationship (p less than 0.001) between both methods. Meconium and blood raised the lecithin level so that these contamination can lead to false positive values. As a result the examined test-combination is a usable method for determining fetal lung maturity from uncontaminated amniotic fluid samples. Because of its specificity and small apparative costs, it further is suited as a standard comparison method to those other existing methods and may lead to standardisation of lung maturity diagnosis.