Cervical ripening and plasma prostaglandin levels. Comparison of endocervical and extra-amniotic PGE2.

Two modes of cervical application of a gel containing PGE2 have been compared in a total of 30 patients with indication for induction of labor and unripe cervix. Fifteen patients had gel injected endocervically; in 10 patients the gel contained 400 micrograms PGE2, in 5 controls the gel was inactive. Fifteen subjects had a 15 ml Foley catheter passed through the cervix and placed extra-amniotically; in 10 of them 3 ml gel with 400 or 800 micrograms PGE2 was injected, while 5 controls received inactive gel. Plasma levels of 13,14-dihydro-15-keto-PGE2 alpha (PGFM) were measured in blood samples drawn before and 1/2, 1, 2, 4, 6, and 8 hours after gel application. Neither the Foley catheter nor the application of inactive gel caused significant changes in the cervical scores or the PGFM levels. PGE2 in the endocervix increased cervical scores without altering plasma PGFM levels. Extra-amniotic PGE2 caused a more rapid increase of the cervical scores and a progressive rise in PGFM levels. The plasma (PGFM) levels were found to be related to the degree and to the rate of cervical dilatation. The correlation with cervical dilatation was highly significant. Labor began spontaneously or after artificial rupture of the membranes in 80% of the extra-amniotic, and 50% of the endocervical PGE2-group, but in none of the controls. These data indicate that increased uterine PGF2 alpha production is not necessary for the early stages of cervical ripening, whereas dilatation beyond 4 cm does not proceed without such increase.