A nick of time?

One of the most common practices in obstetrics is amniotomy, the artificial rupture of the amniotic membranes during labour. It is thought that this practice speeds up contractions and thus labour. But what is the evidence for this belief? Is this practice safe for both the baby and the mother? Potential risks include umbilical cord prolapse, abnormal fetal heart tracings, and necessity for cesarean section delivery.

The Cochrane Collaboration recently published a systematic review to assess the effectiveness and safety of amniotomy in normally progressing spontaneous labours and in spontaneous labours that had become prolonged.

The Cochrane Pregnancy and Childbirth’s Trials Register was searched for randomized controlled trials comparing amniotomy alone versus intention to preserve the membranes; 14 trials were eligible for assessment. Almost 5000 women were involved in these trials. There was no consistency among the trials as to the timing of amniotomy (eg, cervical dilatation).

The researchers found no statistical difference in the length of the first stage of labour between the amniotomy and the intention-to-preserve-the-membrane groups. Maternal satisfaction with the childbirth experience was similar in both groups. There was no difference in low Apgar scores (< 7 at 5 min) between the 2 groups. Amniotomy was associated with increased risk of delivery by cesarean section, but this difference was not statistically significant. None of the studies assessed the effect of amniotomy on women’s pain in labour.

The authors conclude that routine amniotomy is not recommended for normally progressing labours or in labours that have become prolonged.

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