Clinical Review

Preserving the VBAC alternative: 8 pearls

OBG Manag. 2004 April;16(4):20-30

References

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We showed an increased risk for uterine rupture with an odds ratio of 3.0 (95% CI 1.2-7.2) for those with interdelivery intervals of up to 18 months compared with those who had interdelivery intervals of 19 months or longer.¹⁵ More recently, Bujold et al¹⁶ confirmed these findings: They found the odds ratio for uterine rupture to be 2.7 (95% CI 1.1- 6.5) for those with an interdelivery interval of up to 24 months.

In a smaller study, Huang et al¹⁷ suggested that the success of trial of labor after cesarean may also be lower for those with interdelivery intervals of up to 18 months.

Pearl 8A vaginal delivery before or after prior cesarean lowers risk of rupture

Patients with a prior vaginal delivery are at significantly lower risk for uterine rupture than those without.

We published a study evaluating women with 1 prior cesarean delivery and either a preceding vaginal delivery or a previous VBAC. Our data suggest that women with a prior vaginal delivery were 5 times less likely to experience uterine rupture than those with no prior vaginal deliveries, either before or after the prior cesarean (odds ratio 0.2; 95% CI 0.04-0.8).¹⁸

Summary and recommendations

To continue to use vaginal birth after cesarean as an obstetrical practice, we must be better able to identify patients at high and low risk for complications from this procedure, and those who have the greatest chance for success. Women with a nonrecurring indication for the prior cesarean (eg, breech) have the best chance for success. Those with recurring indications for the prior cesarean (eg, failure to progress, morbidly obese women, those with macrosomic fetuses, and those with short interdelivery intervals) may have lower success rates.

Patients contemplating a future trial of labor should consider avoiding pregnancy for at least 9 to 15 months after cesarean delivery.

How can we reduce the risk of uterine rupture in women who are considering a trial of labor after prior cesarean delivery?

We should not give these women prostaglandins for cervical ripening.
We must consider allowing a trial of labor for those in spontaneous labor, and be more hesitant about inducing the labor in these patients.
Women with multiple prior cesareans may also benefit from avoiding a trial of labor.
Having patients avoid pregnancy for at least 9 months, and maybe up to 15 months, after a cesarean delivery could also assist with decreasing our rate of uterine rupture.
Keep in mind that those with prior vaginal delivery have a much lower rate of uterine rupture.

These findings call for some type of scoring system to more precisely define the risk for an individual patient who is contemplating a trial of labor after prior cesarean delivery.

The authors report no financial relationships relevant to this article.