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When is OVD indicated? When do the risks outweigh the potential advantages? What should your pre-op assessment include? To answer these and related questions, two experts take an in-depth look at the research data.
Times have changed. Of the more than 4 million livebirths in 2002 in the United States, 26.1% were cesarean deliveries. That's the highest rate ever. The vaginal birth after cesarean rate fell from its 1996 peak by half to 12.6%, while preterm and low birthweight levels rose. The rate of delivery by forceps or vacuum has continued to decline, with 5.9% of all births occurring as an operative vaginal delivery (OVD).1
Although experts continue to argue about when a C/S should be performed, few would question the wisdom of maintaining and sharpening one's skills in OVD. To accomplish that goal, we'll review both forceps and vacuum extraction, look at current trends in clinical practice, and present the evidence to support the use of each approach.
Looking back before we look forward Operative vaginal delivery has its origins in an era when fetal and maternal mortality and morbidity rates were quite high. Often, the death of the fetus was deliberately induced in an effort to save a pregnant woman who had experienced a prolonged obstructed labor. But over time and with the introduction of new tools, operative vaginal delivery emerged as a way to both minimize maternal risk and successfully deliver a live baby.
The rates of OVD, as well as the relative use of forceps in comparison to vacuum extraction, have varied considerably over time. There have been significant regional variations within the US and reduced rates of OVD overall and increased use of vacuum assisted devices as a percentage of OVDs. In the US, 5.9% of livebirths in 2002 were accomplished using an operative vaginal approach. That's a 61% decline in the rate of OVDs since the most recent peak in 1994 at 9.5%.1 Although the total rate of OVDs was the same in 1989 and 1997 (9%), the percentage of births delivered by forceps declined from 5.5% to 2.8% and the vacuum extraction rate increased from 3.5% to 6.2 %.2
We can attribute part of this shift in emphasis to concerns that mid-pelvic forceps deliveries harm the newborn. During the 1980s, for example, evidence was presented that operative mid-pelvic vaginal delivery and significant fetal rotation resulted in unbalanced harm to the fetus and should be abandoned.3 More recent evidence, however, suggests that the rate of neonatal compromise after delivery in current judicious practice may be related more to intrapartum events like labor dystocia than to the method of delivery.
The research indicates that an obstetrician can safely achieve vaginal delivery with either forceps or vacuum extractors.4 The real questions now center around the maternal consequences and our ability to predict who will have a successful OVD, and whether there is a difference in pelvic floor function if a woman has second-stage dysfunction and then delivers vaginally or abdominally.5,6
When is assisted delivery indicated-and contraindicated? As the maternal risks of cesarean delivery have diminished and the risks of OVD have become more clearly defined, there have been changes in the acceptable indications for an operative vaginal attempt. In June 2000, an ACOG Practice Bulletin outlined several indications for OVD, recognizing that no indication is absolute.7
When the fetal head is engaged and the cervix is fully dilated, ACOG recommends OVD for: