The ultrasonic changes in the maturing placenta and their relation to fetal pulmonic maturity.

A practical classification of placental maturity changes has been developed based on a review of multiple ultrasound evaluations of placental texture over a 4 year period. This classification grades placentas from 0 to 3 according to specific ultrasonic findings at the basal and chorionic plates as well as within the substance of the organ itself. The placentas of 129 patients were graded according to this system at the time of ultrasound evaluation. Eighty-six patients had placentas classified as Grade 1 or greater and all of these had lecithin-sphingomyelin (L/S) ratio determinations performed. Mature L/S ratios (2.0) were found in 68% of Grade I (21/31), 88% of Grade II (28/32), and 100% of Grade III placentas (23/23). These results suggest a correlation between maturational changes of the placenta as seen by ultrasound and fetal pulmonic maturity as indicated by L/S ratio.