Results
During the study period, 420 patients were recruited, 210 from each center. (Figure 1. Study Enrolment flowchart.)
In the DBC group, 3 women were excluded because of age criteria and deviation from study protocol. One patient was excluded because of prelabour rupture of membranes after randomisation and before the DBC was inserted and 4 patients had incomplete data. During labour, 5 patients had malpresentation and had to undergo a caesarean section, these patients were excluded from the analysis. In the prostaglandin group, 4 patients were excluded because of age criteria and deviation from study protocol, 4 patients were dilated to more than 3 cm after the randomisation and before the insertion of the vaginal prostaglandin and excluded. One patient was not induced as she declined induction of labour after the randomisation. During labour, 3 patients had malpresentation and had to undergo a caesarean section, they were also excluded from the analysis. The demographics and baseline characteristics were similar in both groups (Table 1). Indications for induction of labour was not significant in both groups (Table S1).
The use of entonox is significantly more in the prostaglandin group than the DBC group, while the use of intramuscular pethidine and epidural was similar in both groups. The average induction to pain relief needed interval was 6.57 (± 2.83) hours in the prostaglandin group and 7.6 (± 2.72) hours in the DBC group. In the double balloon catheter group, 141 patients (71.9%) did not need pain relief during the first 12 hours of induction (Table 2).
Adverse events during the first 12 hours of induction were recorded (Table 3). All patients who had hyperstimulation had intrauterine resuscitation with a change to left lateral position and intravenous hydration. Three patients needed tocolysis with intravenous terbutaline, none required delivery due to persistent non-reassuring fetal status. There were two cases of hyperstimulation occurred in the DBC arm, but none had an impact on the fetal status. There were no incidences of intrauterine deaths in both groups.
Although there was no difference in the time to delivery in both groups, the time for dilation to 4 cm was significantly less in the DBC group than the vaginal prostaglandin group (p<0.0001) (Figure 2.). Oxytocin use for augmentation of labour was significantly higher in the DBC group. 52 patients in the prostaglandin group, underwent spontaneous rupture of membranes (p<0.0001). There were no significant differences in the mode of delivery in both groups (Table 4). In the prostaglandin group, a significant number of women had a cesarean section because of failed IOL (p=0.0369), while a significant number of patients who had the DBC allocation had a caesarean for failure to progress in the first stage of labour.
Neonatal outcomes were similar in both study groups (Table S2).