Plasma prostaglandin metabolite levels after use of prostaglandin E2 gel for cervical ripening.

An ideal agent for cervical ripening should produce an increase in cervical scores without stimulating myometrial contractions. Currently used methods of preinduction ripening with prostaglandin E2 are frequently associated with contractions, limiting their use in high-risk patients. To discriminate between a direct effect of absorbed prostaglandin E2 and a triggering of the intrinsic mechanisms of labor, we measured circulating levels of stable metabolites of prostaglandin E2 and prostaglandin F2 alpha. Prostaglandin E2 gel insertion followed by a rise in prostaglandin E2 metabolite but not prostaglandin F2 alpha metabolite implies that contractions are secondary to absorbed prostaglandin E2.