Predicting a failed induction.

BACKGROUND

A failed induction usually refers to failure to progress to the active phase of labour; however, there is no consensus regarding when an induction has failed.

AIMS: To investigate the factors (particularly length of latent phase) that may influence mode of birth for women undergoing Syntocinon induction of labour.

METHODS

A retrospective analysis of 978 nulliparous women undergoing Syntocinon induction of labour following artificial or spontaneous rupture of membranes was performed.

RESULTS

As the length of the latent phase increased, the likelihood of birth by caesarean section increased significantly (P < 0.001). After ten hours of Syntocinon administration, the 8% of women not in the active phase of labour had approximately a 75% chance of being delivered by emergency caesarean section and after 12 h the chance was almost 90%. Multivariate analysis also suggested an association between birth by caesarean section and use of prostaglandin gel (P < 0.001) or mechanical methods of cervical priming (P = 0.004), maternal height < 155 cm (P = 0.020) and cervical dilation prior to commencement of Syntocinon (P = 0.018).

CONCLUSIONS

It would seem reasonable to continue a Syntocinon infusion for at least ten hours in women undergoing induction who have yet to reach the active phase of labour ( 4 cm), and unclear benefit in continuing an induction beyond 12 h. The duration of latent phase is a helpful predictor of subsequent mode of birth.