Epidural bupivacaine/fentanyl infusions vs. intermittent top-ups: a retrospective study of the effects on mode of delivery in primiparous women.

This study was designed to determine whether the introduction of epidural infusions containing fentanyl and bupivacaine has affected the mode of delivery in primiparous women attending our maternity department. We reviewed retrospectively the computerized records of 4362 consecutive primiparous women in labour. All the women were admitted with the expectation of a vaginal delivery. The results were analysed using logistic regression analysis adjusted for age, weight, gestation, cervical dilatation at epidural insertion, use of oxytocin, the year of entry into the study and the type of epidural block received. In women receiving an epidural block at 3-6 cm cervical dilatation (n = 1534), those who received an infusion were significantly less likely to have an emergency Caesarean section than those having intermittent 'topups' (P = 0.0019). In the same subgroup of women, the Caesarean section rate specifically for failure to progress followed the same trend, but just failed to reach statistical significance (P = 0.058). This provides evidence to support the theory that epidural infusions containing a low dose bupivacaine/fentanyl combination may reduce the risk of Caesarean section in primiparous women.