RCT design
A multi-center randomized controlled trial was undertaken across eight Australian maternity hospitals, between September 2015 and October 2018. The study compared the use of outpatient balloon catheter cervical priming IOL with inpatient PG (Dinoprostone) vaginal gel or tape. The methods are described in detail elsewhere (16). In summary, eligible women had a live singleton pregnancy, cephalic presentation, at or beyond 37+0 weeks gestation, and were undergoing IOL for low-risk indications. Women presented to hospital in the early evening. Those randomized to the inpatient-PG group were admitted to hospital, administered PG as 2mg Dinoprostone vaginal gel (Prostin) or 10mg Dinoprostone controlled-release vaginal tape (Cervidil), and then remained as an inpatient until birth. Women randomized to the outpatient-balloon group had a double-balloon catheter (Cervical Ripening Balloon plus stylet; Cook Medical, Bloomington, US) placed during a digital vaginal examination. Following 30 minutes of observation, the woman was given written information about the reasons to return earlier and how to call the hospital, and discharged home for approximately 12 hours. For women in both groups, early clinical review occurred if there was vaginal bleeding, fluid loss, painful contractions, expulsion of the balloon, or the woman needed pain relief. Otherwise, women were reviewed in birth suite the following morning, approximately 12 hours after commencement of her IOL. At this review, an amniotomy was attempted, and a Syntocinon infusion commenced as soon as possible. Women completed a written questionnaire postpartum (prior to hospital discharge), measuring their healthcare experience and this included an assessment of health-related quality of life. The primary outcome measure was a composite measure of neonatal outcomes. Healthcare cost was a secondary outcome measure.