by Henci Goer
Commentary on: McMahon, M. J., et al. (1996). Comparison of a trial of labor with an elective second cesarean section. N Engl J Med 335(10): 689-95. [Abstract]
Study design and results: evaluation of outcomes in 6138 women with prior cesarean section (3249 planned vaginal birth; 2889 planned elective repeat cesarean) at 27 Nova Scotia hospitals. The study concluded that “major maternal complications” occur nearly twice as often with VBAC as with elective repeat cesarean section.
- major complications (hysterectomy, uterine rupture, operative injury):
- 1.6% planned VBAC
- 0.8% elective repeat cesarean
- odds ratio: 1.8; 95%
- confidence interval 1.1 to 3.0
- minor complications (fever, hemorrhage requiring transfusion, abdominal wound infection):
- 6.3% planned VBAC
- 7.6% elective repeat cesarean
- VBAC rate: 60%
- perinatal outcomes: Apgar scores, rates of admission to neonatal intensive care, and perinatal mortality rates were similar between the two groups.
Problems include but are not limited to the following:
- The investigators coded wound infection and hemorrhage requiring transfusion as “minor complications”: These would normally be considered major complications. Coding them as such would have wiped out the difference between groups.
- According to a recent systematic review, 75% is an achievable VBAC rate (1) whereas here it was only 60%: The more women who have cesareans in the planned vaginal birth group, the worse planned VBAC will look because cesarean delivery is much more likely to result in complications than vaginal birth.
Bibliography:
- Guise JM, Berlin M et al. Safety of vaginal birth after cesarean: a systematic review. Obstet Gynecol 2004;103:420-9.