Maternal Complications with Vaginal Birth After Cesarean Delivery: A Multicenter Study
Maternal Complications with Vaginal Birth After Cesarean Delivery: A Multicenter Study
Abstract & Commentary
By John C. Hobbins, MD, Professor and Chief of Obstetrics, University of Colorado Health Sciences Center, Denver, is Associate Editor for OB/GYN Clinical Alert.
Synopsis: Women with a prior cesarean should be offered VBAC, and women with a prior cesarean and prior vaginal delivery should be encouraged to VBAC. Although other studies have suggested that prostaglandins should be avoided, we suggest that inductions requiring sequential agents be avoided
Source: Macones GA, et al. Maternal complications with vaginal birth after cesarean delivery: A multicenter study. Am J Obstet Gynecol. 2005;193:1656-1662.
There are many factors responsible for the plummeting rate of vaginal birth after cesarean sections (VBACs). However, the major reason for the downward swing is the concern about uterine rupture and its maternal and fetal ramifications.1-3
Perhaps the largest study to address the true rate of rupture in VBACs surfaced this November in the American Journal of Obstetrics and Gynecology by Macones and colleagues. The lead author is a well-known expert on decision-making analysis.
Macones et al sifted through delivery data from 17 centers during 1996 through 2000. In this study, 25,005 patients were identified who had had previous cesarean sections—11,299 (44%) were sectioned outright and 13,706 (56%) chose to attempt a VBAC. Of the 12,535 patients having had only one prior cesarean section, 9,462 had a successful vaginal delivery (75.5%), while those with two or more prior sections had a similar success rate (878 of 1,171 or 75.0%). The group then assessed the risk of uterine rupture, which was strictly defined as separation of the scar noted at the time of laparotomy in the face of evidence of maternal bleeding or non-reassuring fetal heart tones. Asymptomatic dehiscence was not included as an end point and vertical or unknown scars were excluded.
In a separate spoke of the study, the group analyzed data from the 134 patients with uterine ruptures in comparison with 655 randomly selected non-ruptured controls regarding a variety of clinical and historical factors.
The results were extremely enlightening. First, the overall rupture rate was 9.8/1000, with a rate of 8.7/1000 in those with a single previous cesarean section and 20/1000 in those with 2 or more prior sections. Factors increasing the risk for rupture included the need for induction and/or augmentation, use of prostaglandin and pitocin together, and, as indicated above, more than 1 previous cesarean section. In this study, as opposed to another earlier study, prostaglandin alone did not increase the rate of rupture (but misoprostol was not used in this study). Maternal age, race, or where the patient delivered (tertiary or primary care hospital) had little effect on the results. However, the one factor that had a major decrease in the chances of uterine rupture was a previous successful vaginal delivery. This reduced the risk by 60%, giving an overall theoretical risk of 5.8/1000.
Commentary
The very latest data from the CDC from 2004 indicates a cesarean section rate in the United States of 29.1%, up from 20.7% in 1996, the year the above authors began including data in their study. Interestingly, the VBAC rate in the United States in 1996 was 28.3%, but in 2004 it was only 9.2%. Although concern for uterine rupture was the primary reason for this drop, other spin-offs have had a major effect on the trend such as litigious factors, patient inconvenience, fear of labor, and provider inconvenience based on ACOG’s admonition that he/she be "immediately available" for all VBAC labors.4,5
This large study speaks for itself. The risk of uterine rupture in those having had one previous section is about 1% and, the risk is about 2% in those having had two or more prior sections. Most importantly, those with one prior section and a previous vaginal delivery run a 99.5% chance of no rupture, a risk I would guess almost every woman committed to a vaginal delivery would take—if we would let her.
References
- Lydon-Rochelle M, et al. Risk of uterine rupture during labor among women with a prior cesarean delivery. N Engl J Med. 2001;345:3-8.
- Caughey AB, et al. Rate of uterine rupture during a trial of labor in women with one or two prior cesarean deliveries. Am J Obstet Gynecol. 1999;181:872-876.
- Landon MB, et al. Maternal and perinatal outcomes associated with a trial of labor after prior cesarean delivery. N Engl J Med. 2004;351:2581-2589.
- American College of Obstetricians and Gynecologists (ACOG). Vaginal birth after previous cesarean delivery. Washington (DC): American College of Obstetricians and Gynecologists (ACOG); 2004 Jul. 10 p. (ACOG practice bulletin; no. 54).
- ACOG Committee on Obstetric Practice. Committee opinion. Induction of labor for vaginal birth after cesarean delivery. Obstet Gynecol. 2002;99:679-680.
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