One of the oldest mechanical methods of artificially starting labour in overdue pregnancies, the Foley catheter*, is as successful (giving similar vaginal delivery rates) as the current treatment of choice in the UK and USA, a hormone-like gel containing prostaglandin E2, but with fewer side effects.
The findings of the PROBAAT trial, published Online First in The Lancet, suggest that a mechanical approach to labour induction could reduce complications, and challenge the current belief that mechanical methods increase the risk of infection for mothers and babies.
"These data should prompt a revision of the recommendation that 'mechanical procedures (balloon catheters and laminaria tents) should not be used routinely for induction of labour'", urge Jane Norman and Sarah Stock from the University of Edinburgh, Edinburgh, UK, in an accompanying Comment.
Labour is induced in around 20-30% of pregnancies worldwide, making it one of the most commonly performed obstetric procedures. Both mechanical and pharmacological methods are used to artificially start labour in women with an unripe cervix in whom the risk of caesarean section is high. Currently, labour is most often induced with prostaglandins, but the optimum method is not known.
"In view of the frequency at which the intervention is done, the variation in clinical practice, and the varying prevalence of adverse outcomes in mostly underpowered trials we did this trial to compare the safety and effectiveness of induction of labour with a Foley catheter with induction with vaginal prostaglandin E2 gel", explains Kitty Bloemenkamp from Leiden University Medical Centre, Leiden, Netherlands, one of the lead authors of the PROBAAT trial.
The study was conducted within the Dutch Obstetric Consortium, at 12 hospitals in the Netherlands, and involved 824 women with an unripe cervix who were randomly assigned to either induction with a Foley catheter (412 women) or prostaglandin E2 (412 women).
Rates of caesarean section were similar in both groups (23% for Foley catheter vs 20% for prostaglandins).
Induction using a Foley catheter reduced the number of operative deliveries for fetal distress, and resulted in significantly fewer babies being admitted to the neonatal ward (12% vs 20%). Additionally, women in the Foley catheter group had lower rates of infection during labour.
Results of a meta-analysis conducted by the researchers (including this new data), confirmed that Foley catheter induction and prostaglandin E2 gel resulted in similar natural delivery rates, but found that Foley catheter induction significantly reduced rates of uterine hyperstimulation (a contraction lasting 3 minutes or more with fetal heart rate abnormalities) and postpartum haemorrhage (severe bleeding after delivery).
The authors conclude: "We think that a Foley catheter should at least be considered for induction of labour in women with an unfavourable cervix at term."
They add: "Because of low cost and easy storage of the Foley catheter, its use could be suitable for developing countries and low-resource settings."
Dr Kitty Bloemenkamp, Leiden University Medical Centre(LUMC), Leiden, Netherlands. Via Communications Department LUMC. T) +31 71 536 8005 E) informatie@lumc.nl
Professor Jane Norman, MRC Centre for Reproductive Health, University of Edinburgh, Edinburgh, UK. Via Tara Womersley, University of Edinburgh Press Office. T) +44 (0)131 650 9836 or +44 (0)7791 355 804 E) Tara.Womersley@ed.ac.uk
Notes to Editors: *A Foley catheter is used to ripen the cervix by inserting a balloon behind the cervical wall where it is inflated. The inflated balloon works by applying pressure to the cervix, similar to a baby's head prior to labour, causing it to dilate.
Journal
The Lancet