Plasma concentration of 13,14-dihydro-15-keto-PGE2 (PGEM) after various ways of cervix ripening with PGE2

PGEM concentration was determined radioimmunologically in a non-pregnant woman, in whom PGE₂ was infused intravenously at increasing rates and in women, in whom labor was induced by various methods for local application of PGE₂. There was excellent correlation between the amount of PGE₂ infused intravenously and the levels of PGEM determined in the peripheral plasma. The following methods of local application of PGE₂ were included in the study: 0.4mg PGE₂ gel placed retroamnially by means of a balloon catheter, 0.4 and 0.5mg PGE₂ applied endocervically and 3mg PGE₂ placed intravaginally in form of a single vaginal tablet; also induced was a control-group, where only vaginal examination was performed. Bloods were drawn before, 30 minutes, 1, 2 and 3 hours after PGE₂ administration. Mean levels of PGEM in the maternal peripheral plasma did not change neither within nor between the various groups. It is concluded from the present study, that local application of doses currently used to soften the cervix and/or induce labor at term do not lead to the same PGEM-concentration in the maternal blood as after intravenous infusion of PGE₂ in doses normally used to induce labor.