Human chorionic gonadotrophin and alpha-fetoprotein levels in matched samples of amniotic fluid, extraembryonic coelomic fluid, and maternal serum in the first trimester of pregnancy.

Separately identified samples of amniotic fluid and extraembryonic coelomic fluid obtained by high resolution transvaginal ultrasound-guided amniocentesis from 32 women between 7 and 12 weeks of pregnancy were analysed for human chorionic gonadotrophin (hCG) and alpha-fetoprotein (AFP). There was a highly significant difference between the hCG levels in amniotic fluid (median level 6.3 U/ml; range 1.6-310.0 U/ml) and those in extraembryonic coelomic fluid (median level 400.0 U/ml; range 135.0-2250.0 U/ml) (p less than 0.001; Mann-Whitney U-test). The levels of AFP were very similar in amniotic fluid (median 26.0 kU/ml; range 10.0-116.5 kU/ml) and extraembryonic coelomic fluid (median level 24.1 kU/ml; range 12.4-94.4 kU/ml).