- Design
- systematic review and meta-analysis of 18 non-randomised studies and two randomised trials, GRADE certainty very low
- Population
- 28,035 observations in trial of labour after previous low-transverse caesarean, including 5,516 balloon exposures
- Primary outcome
- complete uterine rupture, reported separately from dehiscence
- Effect
- vs prostaglandins OR 0.43 (95% CI 0.26-0.72); vs spontaneous labour OR 1.29 (0.90-1.84); dehiscence OR 1.86 (1.06-3.29)
Twenty studies — 18 non-randomised and two randomised — contributed 28,035 observations, including 5,516 exposures to a Foley, single-balloon or double-balloon catheter during trial of labour after a previous low-transverse caesarean. Comparator-specific odds ratios were estimated by Mantel-Haenszel methods, with risk of bias judged on ROBINS-I, Newcastle-Ottawa and RoB 2, and certainty on GRADE.
Against prostaglandin induction, balloon ripening was associated with lower odds of complete uterine rupture (OR 0.43, 95% CI 0.26-0.72), a risk difference of about 19 fewer ruptures per 1,000. Against spontaneous labour no difference was detected (OR 1.29, 95% CI 0.90-1.84, falling to 1.09 when the most influential cohort was excluded), nor against oxytocin alone. Pooled across all pharmacological comparators the odds ratio was 0.40 (0.25-0.66).
The counterweight sits in the same analysis: dehiscence was reported more often after balloon-based induction (OR 1.86, 1.06-3.29) across five studies, with the same direction against every comparator. Certainty was rated very low throughout, and in nearly every protocol the catheter was followed by amniotomy, oxytocin or both — so what was measured is a balloon-based strategy, not a mechanical device in isolation.
For a unit that already offers trial of labour, this supports keeping mechanical ripening as the method of choice where induction is indicated and the cervix is unfavourable, with continuous monitoring and immediate theatre access unchanged. It is not a reason to widen who is offered induction after caesarean.
- Where induction is indicated in a woman planning trial of labour after caesarean, mechanical ripening remains a reasonable choice over prostaglandins
- Continuous fetal monitoring and immediate access to emergency caesarean are prerequisites, not optional additions
- Document that amniotomy or oxytocin, or both, will usually follow catheter placement — the risk estimate belongs to the whole sequence
- Counsel that dehiscence was reported more often with a balloon-based strategy, even where complete rupture was not
- Check the previous operation note for a low-transverse incision before offering trial of labour at all
Why it matters
The fear that a catheter mechanically provokes rupture is what keeps some units from inducing after caesarean at all.
Don't overread it
These were almost all observational comparisons at very low certainty, and cannot show that the catheter itself is what made the difference.
The statistics, in plain English
An odds ratio of 0.43 with an interval of 0.26 to 0.72 excludes 1.0, so the comparison with prostaglandins is unlikely to be chance. The comparison with spontaneous labour, 1.29 with an interval from 0.90 to 1.84, crosses 1.0 in both directions — it is consistent with a small increase or a small decrease, and cannot exclude either. The dehiscence interval, 1.06 to 3.29, only just clears 1.0, so that signal is real but imprecise. GRADE certainty was very low because almost all the data are observational, which means the point estimates could shift with better studies.
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