Amniotomy for shortening spontaneous labour

Smyth RMD, Alldred SK, Markham C

Summary

Amniotomy for shortening spontaneous labour

Evidence does not support the routine breaking the waters for women in spontaneous labour.

The aim of breaking the waters (also known as artificial rupture of the membranes, ARM, or amniotomy), is to speed up and strengthen contractions, and thus shorten the length of labour. The membranes are punctured with a crochet-like long-handled hook during a vaginal examination, and the amniotic fluid floods out. Rupturing the membranes is thought to release chemicals and hormones that stimulate contractions. Amniotomy has been standard practice in recent years in many countries around the world. In some centres it is advocated and performed routinely in all women, and in many centres it is used for women whose labours have become prolonged. However, there is little evidence that a shorter labour has benefits for the mother or the baby. There are a number of potential important but rare risks associated with amniotomy, including problems with the umbilical cord or the baby's heart rate.

The review of studies assessed the use of amniotomy routinely in all labours that started spontaneously. It also assessed the use of amniotomy in labours that started spontaneously but had become prolonged. There were 14 studies identified, involving 4893 women, none of which assessed whether amniotomy increased women's pain in labour. The evidence showed no shortening of the length of first stage of labour and a possible increase in caesarean section. Routine amniotomy is not recommended for normally progressing labours or in labours which have become prolonged.