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Trials and tribulations of operative vaginal delivery

The notion that operative vaginal delivery has declined in the wake of escalating caesarean section rates is not evidence based. In England, despite a progressive increase in caesarean deliveries over the past 20 years, reaching 23% of births in 2004, the instrumental delivery rate has remained relatively stable at 10–11% of all births.1 Similar trends are evident throughout the UK and North America.2 In Australia, in 2004, more than 29% of women across the nation had their babies delivered by caesarean section; yet, the instrumental delivery rate has remained steady at 11% for the past 10 years.3 The increase in caesarean deliveries, therefore, cannot be explained by a shift from instrumental-assisted births. During the same period, operative vaginal delivery has undergone a dramatic change in practice manifested by a decline in the number of forceps deliveries and a concomitant increase in vacuum extractions. In most reports, the vacuum extractor has now become the preferred instrument for assisted delivery.1,3 The Royal College of Obstetricians and Gynaecologists (RCOG) has issued evidence-based guidelines to increase safety of operative vaginal delivery for mothers and babies and to reduce the likelihood of litigation for medical practitioners and health institutions.4 One of the key recommendations of the guideline (section 5.2) is that ‘operative vaginal births that have a higher rate of failure should be considered a trial and conducted in the operating theatre where immediate recourse to caesarean section can be undertaken’. The rationale behind this recommendation is that fetal injuries have been attributed to the time delay between failed operative vaginal delivery and caesarean section. The benefits should be obvious yet, as the guideline admits, evidence to support this practice is limited. Olagundoye and MacKenzie in this issue of the journal (pages 603–8) report the findings of their evaluation of the impact of a trial of instrumental delivery in the operating theatre in terms of the decision-to-delivery intervals (DDI), mode of delivery and neonatal condition at birth.5 They concluded that on average, the DDI for instrumental procedures in the operating theatre were some two to three times longer than for deliveries undertaken in the labour ward room. Either way, their data showed no significant differences in short-term neonatal or maternal outcomes and do not provide support for the recommendation in the RCOG guideline. The DDI have been studied extensively in relation to emergency caesarean section, where delivery within 30 minutes has generally been accepted as the benchmark. Nevertheless, this recommendation is not achieved in up to 50% of emergency caesarean sections and is therefore an unrealistic target for clinical practice.6 Furthermore, large national and multicentre studies have reported no differences in neonatal or maternal outcomes for emergency caesarean sections when the delivery interval was less than 30 minutes compared with the intervals of longer than 30 minutes and up to 75 minutes.7,8 For forceps delivery and vacuum extraction, the DDI and its effects on neonatal outcome are less clear. A prospective analysis of 90 forceps and 135 vacuum deliveries reported that in cases of fetal distress, the mean DDI for forceps delivery (23 minutes) was significantly shorter than that for vacuum extraction (29 minutes).9 In the Portsmouth study, the mean interval from time of application of the forceps to delivery was shorter than that for vacuum extraction, but the interval from the decision to delivery was the same for both instruments.10 This is plausible when considering the number of steps involved in performing an operative vaginal delivery prior to application of the device.11 The preoccupation with DDI has diverted the focus from problems related to instrumental delivery that need urgent attention. Of particular importance are the high failure rates reported for vacuum extraction and the potential for injury associated with a failed instrumental delivery.12 In the analysis by Olagundoye and MacKenzie, 30 (22%) of the vacuum extractions were unsuccessful at the initial attempt, whereas