The most rare yet most serious risk of vaginal birth after caesarean (VBAC) is that the scar on the uterus may break open (rupture) during labour. Women who have a low transverse caesarean scar have a lower risk of rupturing than women who have a vertical incision scar. About 5 out of 1,000 women (0.5%) with a low transverse scar have a uterine rupture during a trial of labour.footnote 1
A woman's risk of uterine rupture increases with:
Each additional uterine surgical scar.
Any uterine scar that reaches above the lower, thinner part of the uterus, such as a vertical (classical) scar.
The use of medicine to start (induce) labour. Some doctors avoid the use of any medicine to start a VBAC trial of labour. Other doctors are comfortable with the careful use of certain medicines to start labour.
In the rare event that a uterine scar ruptures, it can be dangerous to both the mother and her infant.
Depending on severity, a rupture can:
Be mild and harmless.
Often be repaired. If it is not repairable, the uterus is removed (hysterectomy).
Cause severe maternal bleeding and a decrease in oxygen to the baby.
Guise JM, et al. (2010). Vaginal birth after cesarean: New insights. Evidence Report (Publication No. 10-E003). Rockville, MD: Agency for Healthcare Research and Quality.
Current as of:
June 16, 2021
Author: Healthwise Staff Medical Review: Sarah Marshall MD - Family Medicine Anne C. Poinier MD - Internal Medicine Adam Husney MD - Family Medicine Kathleen Romito MD - Family Medicine Femi Olatunbosun MB, FRCSC - Obstetrics and Gynecology Kirtly Jones MD - Obstetrics and Gynecology
Medical Review:Sarah Marshall MD - Family Medicine & Anne C. Poinier MD - Internal Medicine & Adam Husney MD - Family Medicine & Kathleen Romito MD - Family Medicine & Femi Olatunbosun MB, FRCSC - Obstetrics and Gynecology & Kirtly Jones MD - Obstetrics and Gynecology
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