A COMPARATIVE CLINICAL EVALUATION OF THE FOAM TEST AND PHOSPHOLIPID ASSAY OF AMNIOTIC FLUID

Summary

Amniotic fluid taken by amniocentesis from patients at varying stages of gestation was analyzed for surfactant by the foam test, total phospholipid phosphorus concentration, and alkali labile phospholipid phosphorus concentration. The total and alkali labile phospholipid concentrations increased, and the ratio of alkali labile to total phospholipid concentration fell slightly as gestational age increased. The mean total and alkali labile phospholipid phosphorus concentrations increased with the foam test score, but there was considerable overlap in the phospholipid concentrations between the different groups of foam test results. In our experience only when the foam test is negative does hyaline membrane disease occur, and even then not invariably. Only when the foam test is negative, therefore, is further analysis of amniotic fluid for surfactant indicated. The simplest procedure is then to measure the amniotic fluid total phospholipid concentration. This will resolve the doubt as to whether the newborn is liable to hyaline membrane disease in about one half of the cases. The suggestions by other workers that the ratio between alkali labile phospholipid and total phospholipid would resolve this doubt has not been confirmed by our study.