Follow the '1% Rule' for VBACs.

We treat labor in patients undergoing vaginal birth after cesarean section too much like normal labor.

Induction takes place in 20%-40% of labors, and that probably goes for VBAC labors as well.

The American College of Obstetricians and Gynecologists' 1999 practice bulletin on VBAC tells us only that one of the criteria for attempting VBAC is that a physician who is capable of monitoring labor and performing an emergency cesarean section should be "immediately available." Nowhere, however, does it define "immediately." Is that in the house? Down the street? Or 30 minutes away by car?

We treat VBAC this way because we do not have a direct answer to the central question: What is the risk of catastrophic fetal injury in VBAC?

Although we cannot find in the literature any single study to answer that question, relatively recent data, if combined and considered together, can help guide us.

When a uterine rupture occurs, the estimated risk of death or serious neurologic injury to the fetus is 20%. We cannot say when it is permissible for the physician to be in his office next door to the hospital during VBAC labor, but we can begin to define higher-risk circumstances that would suggest that the physician be in the hospital.

Those data suggest that misoprostol induction is contraindicated in VBAC and cervical ripening with prostaglandin gel may be unwise. The rate of uterine rupture during VBAC with misoprostol appears to be 5% or greater. The literature regarding prostaglandin gel in VBAC is somewhat confusing. Some studies have not found a higher rupture rate with prostaglandin gel, but other studies have shown a rupture rate ranging from a little more than 1% up to almost 4%.