Amniotic fluid volumes in pregnant diabetics during the last trimester. A comparative study using ultrasound and PAH dilution.

Amniotic fluid was measured by ultrasound and PAH dilution technique in 15 insulin-dependent diabetics during the last trimester of pregnancy. Total uterine volume and fetal volume were estimated by ultrasound. The amniotic fluid volume was obtained by subtracting fetal volume and approximated values for placental volume obtained from the literature from the total uterine volume. The mean amniotic fluid volume determined by ultrasound was 1261 ml (range 278-3563). The mean amniotic fluid volume determined by PAH dilution was 1264 ml (range 344-3852). The values for amniotic fluid determined by these two methods were closely correlated (r = 0.96).