Effect of predilatation of the uterine cervix by laminaria tent on activity of the placenta.

Serum concentrations of hCG were determined in blood samples taken 18-20 h and immediately before vacuum aspiration in 45 women in gestational weeks 7-9, admitted for legal abortion. In 35 of the women, a laminaria tent was inserted for cervical dilatation immediately after the first blood sampling. Serum hCG values decreased significantly in the women pretreated with laminaria tent, but were unchanged in the untreated women. This finding may indicate that pretreatment with a laminaria tent induces a partial placental detachment.