Coelomic fluid chorionic gonadotrophin and protein concentrations in normal and complicated first trimester human...

Coelomic fluid and maternal serum samples were collected from 43 normal pregnancies and 18 missed abortions between 7 and 12 weeks of gestation. The samples were analysed for the concentrations of intact human chorionic gonadotrophin (HCG), free alpha HCG, free beta HCG and total protein. The relationships between the biological findings and the ultrasound and pathological features were assessed by regression analysis. In normal pregnancies, intact HCG, free alpha HCG and free beta HCG concentrations were respectively 1.3, 185 and 33 times higher in coelomic fluid than in maternal serum. The coelomic concentrations of intact HCG and free alpha HCG decreased significantly with advancing gestation. No relationship was found between coelomic fluid and maternal serum concentrations of the different variables. These findings suggest that in normal pregnancies, the concentration of HCG in the coelomic fluid, as in maternal serum, is mainly influenced by cytotrophoblastic differentiation and that the metabolic clearance of HCG molecules is slower in the coelomic cavity than in maternal serum. In missed abortions, the serum concentrations of intact HCG, alpha HCG and free beta HCG and the coelomic concentration of total protein were significantly lower than in normal pregnancies. In three out of nine anembryonic pregnancies diagnosed by ultrasound, embryonic remnants were present at histological examination. The coelomic concentration of total protein was extremely low in all missed abortions with advanced trophoblastic necrosis whereas the HCG concentration was low when embryonic remnants were absent. These findings support the concept that embryonic and placental development are closely related in the first trimester of human pregnancy, placental biological functions persisting only for a limited period of time after embryonic demise.