Functional and biochemical aspects of laminaria use in first-trimester pregnancy termination

The effect of laminaria-induced cervical dilatation of plasma levels of the prostaglandin metabolite 13, 14-dihydro- 15-keto prostaglandin (PGFM) was evaluated in women undergoing elective first-trimester pregnancy termination. Seventy-one women were randomly assigned to either a treatment (n = 45) or control (n = 26) group. Cervical dilatation measured at the time of insertion of the laminaria was 3.0 +/- 0.1 mm compared to 10.2 +/- 0.2 mm at the time of removal of the laminaria 14 to 16 hours later (p less than 0.001). Peripheral levels of PGFM rose from 28.3 +/- 2.4 pg/ml (mean +/- SEM) to 43.0 +/0 2.6 pg/ml at the time of removal of the laminaria (p less than 0.001). Peripheral concentrations of PGFM in controls remained unchanged. Peripheral concentrations of PGFM did not correlate with the patient's symptoms. Although the hydrophilic property of laminaria is considered to be the principal mechanism promoting cervical dilatation, laminaria may alter the elaboration, release, or degradation of uterine prostaglandin F2 alpha. Thus, biochemical as well as mechanical factors may enhance cervical dilatation in laminaria-treated women.