A comparison of three preinduction cervical priming methods: prostaglandin E2 gel, Dilapan S rods and Estradiol gel

The aim of the study was to evaluate the efficacy of three cervical priming methods. From January 1, 1994 to December 31, 1996 247 patients presenting an indication for induction of labor with an unripe cervix were randomly assigned to one of the following preinduction protocols: 0.5 mg of Prostaglandin E2 gel administered intracervically (n = 83), four hygroscopic Dilapan S rods applied intracervically (n = 82), and 150 mg of Estradiol gel administered intravaginally (n = 82). The inclusion criteria were the patient's informed consent, singleton pregnancy of more than 36 weeks, cephalic presentation, Bishop score < 5 points and reactive non-stress test. If the cervical maturation (Bishop score > or = 5, and/or Bishop score augmentation by 2 points) did not occur after 14 hours of priming, the case was considered a failure. In the opposite case the patient was induced by means of extraamniotic PGE2 administration. The mean gain in the Bishop score was 3.7 points in the PGE2 group 3.9 points in the Dilapan S group, and 2.8 points in the Estradiol group. 71 patients (85.5%) were successfully preinduced in the PGE2 group, 73 (89.0%) in the Dilapan S group, and 63 (76.8%) in the Estradiol group. Labor was induced by preinduction only in 23 patients (31.3%) of the PGE2 group in 17 (20.7%) of the Dilapan S group, and in 14 (17.1%) of the Estradiol group. The mean induction to delivery interval was 7 h 27 min in PGE2 group, 7 h 49 min in the Dilapan S group and 9 h 15 min in the Estradiol group. The Caesarean section rate was 24.4% in the PGE2 group, 10.5% in the Dilapan S group, and 24.4% in the Estradiol group. PGE2 gel and Dilapan S rods proved higher efficacy than Estradiol gel. The highest frequency of labor induced by preinduction only was in the PGE2 group. There were shorter induction to delivery intervals in the PGE2, and Dilapan S groups. The lowest Caesarean section rate was in the Dilapan S group. Neither serious side effects nor negative neonatal outcome were noted in either group.