Amniotomy for induction of labour
A network meta-analysis 2 assessed the relative effectiveness, safety and cost-effectiveness of labour induction methods. 611 trials were included. The interventions most likely to achieve vaginal delivery within 24 hours were intravenous oxytocin with amniotomy (posterior rank 2; 95% credible intervals (CI) 1 to 9) and higher-dose (≥ 50 µg) vaginal misoprostol (rank 3; 95% CI 1 to 6) (table T1). Compared with placebo, several treatments reduced the odds of caesarean section, but there were considerable uncertainty in treatment rankings. For uterine hyperstimulation, double-balloon catheter had the highest probability of being among the best 3 treatments, whereas vaginal misoprostol (≥ 50 µg) was most likely to increase the odds of excessive uterine activity.
Table 1. Interventions for failure to achieve vaginal delivery within 24 hours
|Active intervention vs placebo||Odds ratio||95% CI|
|i.v. oxytocin with amniotomy||0.05||0.07 to 0.32|
|Vaginal misoprostol ≥ 50 μg||0.09||0.06 to 0.24|
|Titrated (low-dose) oral misoprostol solution||0.10||0.07 to 0.29|
|Vaginal misoprostol < 50 μg||0.11||0.09 to 0.32|
|Buccal/sublingual misoprostol||0.11||0.05 to 0.19|
|Vaginal PGE2 pessary (normal release)||0.11||0.04 to 0.16|
|Oral misoprostol tablet ≥ 50 μg||0.16||0.05 to 0.20|
|Double-balloon or Cook’s catheter||0.18||0.01 to 0.16|
|Foley catheter||0.19||0.09 to 0.46|
|Oral misoprostol tablet < 50 μg||0.22||0.07 to 0.39|
A Cochrane review 1 included 2 studies with a total of 310 subjects. No conclusions could be drawn from comparisons of amniotomy alone versus no intervention, or amniotomy alone versus oxytocin alone. One trial compared amniotomy alone with a single dose of vaginal prostaglandins for women with a favourable cervix, and found a significant increase in he need for oxytocin augmentation in the amniotomy alone group (44% versus 15%, RR 2.85, 95% CI 1.82 to 4.46).
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