ULTRASOUND-DETECTED FREE-FLOATING PARTICLES IN AMNIOTIC-FLUID - CORRELATION WITH MATERNAL SERUM ALPHA-FETOPROTEIN

The objective of this study was to determine the rate of ultrasound-de tected free-floating particles in amniotic fluid during the early seco nd trimester and their relationship with maternal serum alpha-fetoprot ein (MSAFP) in patients with normal amniotic fluid alpha-fetoprotein ( AFAFP). Ninety-eight consecutive patients undergoing second-trimester amniocentesis for various indications were prospectively studied. Befo re undergoing amniocentesis, each patient had a level II ultrasound ex amination and evaluation of the presence of free-floating particles. A subjective estimate of the particle amount and measurement of the siz e of the largest particle seen were made. Patients were stratified int o three groups according to their MSAFP level (low, normal, high). Sta tistical significance of results was assessed by analysis of variance and multiple comparison procedure, and by nonparametric procedures, as appropriate. MSAFPs (mean +/- 1 SD) were 0. 41 +/- 0.18 and 4.88 +/- 2.22 multiples of the median for the low and the high groups, respecti vely. All AFAFPs were within normal limits. Ninety-four percent of pat ients with high MSAFP had free-floating particles in amniotic fluid as compared to 43% in the low and normal groups (p < 0. 0 1). Patients w ith high MSAFP had significantly greater density and size of particles . The presence of ultrasound-detected free-floating particles in amnio tic fluid of normal patients during the early second trimester may pre clude its use as a reliable indicator for fetal lung maturity, or sugg est that the source of these particles may differ by trimester. High M SAFP is significantly correlated with the ultrasonographic appearance of free-floating particles, as well as with larger size and higher amo unt.