Correlation of human chorionic gonadotropin secretion in early pregnancy failure with size of gestational sac and placental histology.

The relationships between maternal plasma human chorionic gonadotropin (hCG) levels, the gestational sac diameter, and histopathologic findings in the placenta were studied in 99 cases of bleeding during the sixth to 15th weeks of pregnancy. In cases of threatened abortion with a successful outcome of pregnancy, the maternal hCG levels and gestational sac diameter were normal, the correlation being significant during weeks seven to ten. In cases of blighted ovum and missed abortion, both the hCG concentration and gestational sac diameter were usually normal during the sixth to eighth weeks of pregnancy. After the ninth week nearly all gestational sac diameters were under the normal range, whereas normal plasma hCG levels were detected occasionally until the 14th week in these doomed pregnancies. Villous structures were histologically normal in ten of the 31 cases of blighted ovum and missed abortion. However, only two of these ten cases showed normal hCG levels and only one had a normal gestational sac diameter immediately before abortion. The results suggest a correlation between the hCG secretion of the trophoblast and gestational sac diameter in cases of bleeding during the early weeks of pregnancy, both in successful and unsuccessful outcome. Normal hCG levels in maternal plasma and nonpathologic histologic findings in the placental tissue often appear to be present in cases of blighted ovum and missed abortion until the second trimester without any mutual correlation.