THE EFFECT OF MATERNAL BLOOD CONTAMINATION ON THE TDX-FLM-II ASSAY

The objective of this paper is to determine the effect of maternal blo od contamination on the TDx-FLM II assay for fetal lung maturation. Th irty-one samples of amnionic fluid (AF) collected from gestations >28 weeks were assayed for AF surfactant-to-albumin ratio using the TDx-FL M II assay. Maternal blood was added to the AF at increasing concentra tions from 1:10 to 1:1280 and the TDx-FLM II was assessed on each samp le. There were 7 mature (>55), 5 transitional (40-54) and 19 immature (<39)specimens. The addition of increasing amounts of maternal blood d ecreased the value of a mature and increased the value of an immature result, Six of the 7 mature values eventually became immature at high levels of contamination. No value below the mature cutoff was raised i nto the mature range by the addition of blood, Samples with values bet ween 21 and 45 had a variable response to maternal blood but none were increased into the mature range. Maternal blood contamination may res ult in a falsely immature or borderline value, but mature results are valid regardless of the degree of contamination.