VBAC: When to Push and When to Cut

Giving birth can be a complicated experience that may be overwhelming, exhausting and a miracle. The birthing process over the years has changed and more women are delivering via cesarean section. In 2009, 32.9% of births in the United States were accomplished by cesarean section (1). Once a woman has had one cesarean section the options for the next delivery are to have a repeat cesarean section or attempt a trial of labor that could result in a vaginal birth after cesarean (VBAC). There are risks and benefits associated with both options, but each should be presented to the patient in an educated manner.

Many factors go into choosing a method of delivery that is safe for the mother and baby. VBAC is successful approximately 70% of the time (2), but this is a very vague statistic. The chance of a successful VBAC depends on many factors that should be addressed early in the pregnancy and as labor progresses. The following studies address certain criteria that need to be considered when calculating individual probability of success for a VBAC. This information is to be used to inform both provider and mother of the best educated prediction on the unpredictable event of birth.

Flamm Admission Scoring

An admission scoring system was introduced by Flamm and colleagues (1997), through a prospective cohort study of women who had a previous cesarean section. The researchers calculated a predictive score of having a successful VBAC based on the data gathered from the females at admission to the hospital through a multivariate logistic regression model. This model allowed for five significant variables (Table 1) to be identified at time of labor that can be calculated into a point system to determine the probability of attempti...

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...the different circumstances of labor (grobman). The second model Grobman created had 12 factors that could be applied during active labor (grobman), but others have labeled the model complicated as it is difficult to assess that many factors in the short time period available (Eden, Metz). Research is still being conducted to find a model that providers and mothers can use effortlessly with high specificity and sensitivity.

A refined predication model for VBAC still needs to be created, but at this time, the current models can assist clinicians and patients in making a more informed decision between an elective repeat cesarean or to attempt a trial of labor to accomplish a VBAC. The scores that are calculated can give a woman more insight into her choice of delivery and possibly give her peace of mind as to the choice she is making for her and her unborn child.