A comparison of HPLC and TLC in the assessment of amniotic fluid lecithin/sphingomyelin ratio.

One hundred amniotic fluid (AF) specimens of women at 28 to 37 weeks gestation were obtained during labor for lecithin/sphingomyelin ratio (L/S ratio) study by using high performance liquid chromatography (HPLC) and thin layer chromatography (TLC). The results are divided into two groups: one with L/S ratio at or more than 2, and the other with L/S ratio of less than 2. Of the 80 measured by HPLC with the ratio of above 2 or 1.3%, one suffered respiratory distress syndrome (RDS); of the 65 measured by TLC also with the ratio of above 2 or 3.1%, two developed RDS. The result bears no great significance here. However, in the groups with L/S ratio of less than two, the results were very significant: 17 of 20 estimated by HPLC happened to have RDS for an incidence of false positive rate of 15% compared with a 54.3% in 16 of the 35 women evaluated by TLC.