Interpretation
Our findings are similar to Du et al. [12] who
also showed a 10 times lower risk of hyperstimulation in the
double-balloon catheter group to the prostaglandin group. However, the
time to first use of pain relief and the percentage not requiring pain
relief in the first 12 hours was still similar in both groups, likely an
inherent development in labour induction.
A recent systematic review [13] on the safety of
the balloon catheter used a random effects model. It included 26 studies
(8292 women) which estimated the prevalence of adverse events to be 0 to
0.26%, “pain and discomfort’ being most common. In this study, none of
the included studies used a double balloon catheter. Our study provides
more data to support the good safety profile of the double balloon
catheter. Solt et al. [14] compared the Bishop
score increment between a DBC and a single balloon catheter, he
concluded that the DBC was more effective that the single balloon
catheter with decreased time to delivery and decreased caesarean section
rates. The usage of a single balloon catheter in induction of labour is
off-licensed, and also requires traction.
Outpatient cervical ripening can be an attractive option because of the
potential for lower costs and patient satisfaction. This is only
possible if the method does not have an adverse effect on the fetus and
does not require medical interventions. Less fetal monitoring may be
required when DBC is used. In this regard, it may still be difficult for
the double catheter balloon to fulfil this role fully, even without
hyperstimulation, given the requirement for analgesia in the first 12
hours in 28.1% of the patients.
Wilkinson et al [9] ran a pilot randomised trial
comparing inpatient and outpatient balloon induction, they found that
patients in the outpatient arm felt less isolated and emotionally alone
while medical staff including midwives and doctors were more comfortable
with the use of a catheter as an option for outpatient ripening with
90% supporting outpatient ripening with the catheter. A local study[5] also showed that the use of DBC showed similar
satisfaction and acceptability in the Singapore population, with 71% of
patients recommending the DBC as the mode for IOL.
Du et al’s systemic review [12] of 9 randomized
controlled studies concluded similar efficacy profiles between the
double balloon catheter and the prostaglandin E2. Our study also showed
similar labour outcomes in both groups with regards to recourse to
caesarean deliveries, but identified the difference in reasons however.
Caesarean delivery for failed induction was more common in the
prostaglandin group and failure to progress in the first stage of labour
more common in the DBC group. Average time to eventual delivery in both
groups was similar. Our study, in particular, demonstrated a more
predictable course of induction and significantly shorter time required
with the DBC from the initiation of IOL to achieving a cervical dilation
of more than 4 cm (91.3% vs 67.6%, p=<0.0001), although
artificial rupture of membranes and augmentation are more frequently
required. We believe this could offer significant advantage to
obstetricians in planning inductions for their patients, as well as
better patient satisfaction. A cost-efficacy study may be useful in
evaluating a best method of induction.
Currently, there are 9 randomized controlled trials[6,15,16,17,18,19,20] involving a double balloon
catheter. The balloon-filling regime is not standardized. In this trial,
we used a standardized non-incremental balloon-filling regime prescribed
according to the manufacturer’s advice. This decreased delays in
achieving full inflation and decreased the time requiring intensive
monitoring of the fetus; hence, we would recommend this as the standard
balloon-filling regime for the double balloon catheter.