Induction of labour using cervical double-balloon (Cook catheter) in outpatient versus inpatient setting (COOK...

Labor is induced in 20-30% of pregnancies. Mechanical induction, using a single or double cervical balloon, has shown comparable effectiveness to pharmacological methods while reducing foetal distress due to hyperstimulation. Therefore, mechanical labour induction is a promising option for outpatient management. We aim to compare clinical outcomes and maternal satisfaction following induction of labour (IOL) using a cervical double-balloon in an outpatient versus inpatient setting.

Randomised controlled trial.

Four Maternity Hospitals in Belgium.

Women with an uncomplicated singleton pregnancy undergoing IOL for low-risk indications including post-term gestational age, macrosomia and patient's request (≥38 0/7 of gestational age).

Participants were randomly allocated by an online randomisation system (1:1 ratio). Because of the nature of the intervention, the study was not blinded. The primary outcome was suboptimal CTG rate after insertion and after removal of the balloon (12 h after insertion or earlier). Secondary outcomes were mode of delivery, C-section rates, time from balloon insertion to birth and from removal to birth, need for additional medications for labour induction and optimisation of labour, pain management and maternal satisfaction. Analysis was performed on an intention-to-treat basis.

Between May 2017 and November 2023, 178 women were randomised to a balloon outpatient group and 180 to a balloon inpatient group. Due to slow recruitment and low event rates in the primary endpoint, enrolment was stopped at 358 patients in November 2023 and secondary endpoints were prioritized. No statistically significant difference was observed in terms of suboptimal CTG rates at balloon insertion (0.6 % vs 1.2 %, P = 1) and balloon removal in the outpatient versus inpatient group (0.6 % vs 3 %; P = 0.21). There were no statistically significant differences in delivery methods (P = 0.22), time from balloon placement to delivery (21.4 ± 6.4 vs 21.8 ± 7.4 h, P = 0.31) and time from balloon removal to delivery (10.1 ± 5.9 vs 10.6 ± 6.9 h, P = 0.64). Maternal satisfaction rates were significantly different and in favour of the outpatient group, in terms of perceived duration of labour (P = 0.039), perceived length of stay in the delivery room (P = 0.037), preference for the same method and setting of induction for future pregnancies (P = 0.034) and as advice to others (P = 0.026).

Our findings suggest that balloon catheters are generally safe and effective for induction of labor in both inpatient and outpatient settings, although this study did not reach the planned sample size. Patients' satisfaction with induction and labour is higher when cervical ripening is performed in outpatient setting.