The foam stability test on gastric aspirate in the prediction of respiratory distress syndrome.

To evaluate the usefulness of the foam stability test (FST) on gastric aspirate for predicting respiratory distress syndrome (RDS) in premature infants, samples were collected at delivery or within 30 min from 194 infants less than or equal to 36 weeks gestation. Of 123 samples adequate for complete testing, 44 were positive at 1 : 2 dilution, 43 were positive only at dilutions less than 1 : 2 and 36 were negative at all dilutions. RDS was found in 2%, 21% and 25% of each group respectively. The FST on gastric aspirate at birth gives useful information only if positive at 1 : 2 when a very low incidence of RDS may be expected. However, a large proportion of infants with FST negative at 1 : 1 do not develop RDS, and hence the test is of limited value in screening for those with highest risk.