Inconsistent evidence: analysis of six national guidelines for vaginal birth after cesarean section

Guidelines are increasingly used to direct clinical practice, with the expectation that they improve clinical outcomes and minimize health care expenditure. Several national guidelines for vaginal birth after cesarean section (VBAC) have been released or updated recently, and their range has created dilemmas for clinicians and women. The purpose of this study was to summarize the recommendations of existing guidelines and assess their quality using a standardized and validated instrument to determine which guidelines, if any, are best able to guide clinical practice.

English language guidelines on VBAC were purposively selected from national and professional organizations in the United Kingdom, United States, Canada, New Zealand, and Australia. The Appraisal of Guidelines for Research and Evaluation (AGREE) instrument was applied to each guideline, and each was analyzed to determine the range and level of evidence on which it was based and the recommendations made.

Six guidelines published or updated between 2004 and 2007 were examined. Only two of the six guidelines scored well overall using the AGREE instrument, and the evidence used demonstrated great variety. Most guidelines cited expert opinion and consensus as evidence for some recommendations. Reported success rates for VBAC ranged from 30 to 85 percent, and reported rates of uterine rupture ranged from 0 to 2.8 percent.

VBAC guidelines are characterized by quasi-experimental evidence and consensus-based recommendations, which lead to wide variability in recommendations and undermine their usefulness in clinical practice.