Cardiotocographic abnormalities associated with dinoprostone and misoprostol cervical ripening

To characterize the frequency and timing of cardiotocographic abnormalities associated with the use of 3 commercially available prostaglandin analogues, misoprostol, dinoprostone gel, and dinoprostone pessary, as labor preinduction agents.

One-hundred and eleven women undergoing induction of labor with an unfavorable cervix were randomized to receive either misoprostol 50 microg every 6 hours x 2 doses, dinoprostone gel 0.5 mg every 6 hours x 2 doses, or dinoprostone pessary 10 mg x 1 dose for 12 hours intravaginally. Oxytocin induction was initiated per standardized protocol. Cardiotocographic tracings were blindly reviewed, with abnormalities coded using established definitions.

Fifty-five percent of women treated with misoprostol demonstrated an abnormal tracing event within the initial 24 hours of induction, compared with 21.1% with dinoprostone pessary and 31.4% with the dinoprostone gel. The mean (+/- standard deviation) number of abnormal events was significantly greater in women treated with misoprostol (5.0 +/- 5.9) versus the dinoprostone pessary (1.6 +/- 2.5) and gel (2.2 +/- 3.1) (P < .05). In addition, these events occurred earlier after initial misoprostol dosing (5.0 +/- 4.0 hours), compared with the dinoprostone pessary (9.4 +/- 5.6 hours) and gel (7.7 +/- 6.6). Thirty-nine percent of the misoprostol-treated women had abnormal patterns within 6 hours of initial dosing, compared with those treated with the dinoprostone pessary (7.9%) and gel (17.1%).

Cardiotocographic abnormalities are more frequent after misoprostol administration compared with the dinoprostone analogues. The early onset and frequent nature of the tracing abnormalities associated with misoprostol raises concern for the potential use of misoprostol for outpatient cervical ripening.