A semi-automated and standardized method of determining the lamellar body content of amniotic fluid

We have simplified and standardized the method of determining the lamellar bodies (LB) in amniotic fluid as a measure of fetal lung maturity. For this purpose we have first diluted the amniotic fluid and then concentrated its LB by low-speed centrifugation at the interface of a 10% Nycodenz solution. As a standard we use liposomes which consist of phospholipids enclosing a Nycodenz solution with a density similar to that of the LB. The phosphorus content of the LB and liposome standard is then determined by an automated fluorimetric method. There is an excellent correlation between the newly described procedure and the lecithin/sphingomyelin ratio. One technician can easily analyse 40 samples in a working day.