TOLAC following ECV: turn with care
In this edition of the journal, Burgos et al. report on a 10–year experience with external cephalic version (ECV) in patients with a prior caesarean section. They compared the ECV success rate and perinatal outcome of 70 women at term with a singleton breech and with one prior low-segment caesarean section against ECV in 387 multiparous women at term with a singleton breech and without a prior caesarean section. The cases and controls were matched for parity, body mass index (BMI), placental location, breech variety, amniotic fluid volume, and estimated fetal weight. Standard consent, ECV protocol, and vaginal birth after caesarean (VBAC) protocol were in place and operative throughout the period of study. Their results demonstrate a success rate of ECV in women with a previous caesarean section of 67.1 versus 66.1% in multiparous control women (P = 0.87). Logistic regression analysis adjusted by the variables associated with the success of ECV confirmed this result (OR 0.93, 95% CI 0.52–1.68, P = 0.82). There were no complications in the previous caesarean section cohort, and no difference in any perinatal outcomes studied (there were seven complications in the multiparous control cohort, necessitating urgent caesarean section in three women, for a 0.77% urgent caesarean rate). The vaginal delivery rate in the previous caesarean section cohort was 52.8 versus 74.9% in the multiparous cohort (P < 0.01). There were no cases of uterine rupture. Based on their data and a review of earlier studies, the authors conclude that a prior uterine scar should not be considered a contraindication to ECV, and that the procedure should be offered to women with previous caesarean section with breech presentation at term.
As the authors note, this study represents the largest contribution so far to the literature on ECV and prior caesarean section. By extension, it is also the largest contribution so far to the literature on trial of labour after caesarean section (TOLAC) following ECV. Although tempting to see these risks and outcomes in a unified manner, ECV in women with a prior caesarean section and TOLAC following ECV are in fact two separate procedures, with related but also discrete risks and outcomes. The results of this study are in line with the generally reassuring outcomes previously reported. Nonetheless, the data is scant − 272 total cases, including this contribution – and pales in comparison with the vastly greater experience of both ECV in women without a prior caesarean section and TOLAC in women who have not had an ECV. If anything, the 0% rate of uterine rupture with TOLAC in these cases in the published literature so far, including this study, highlights the limitations of the available data. The 2000 (reaffirmed 2012) Practice Bulletin on ECV from the American College of Obstetricians and Gynecologists (ACOG) states that ‘previous cesarean delivery is not associated with a lower rate of success; however, the magnitude of the risk of uterine rupture is not known’ (External cephalic version. Practice Bulletin No. 13. American College of Obstetricians and Gynecologists. 2000). The bulletin rates this recommendation as level–B evidence (limited or inconsistent scientific evidence). Affirming the limited data available and the level–B evidence, the 2010 (reaffirmed 2013) ACOG Practice Bulletin on Vaginal Birth After Prior Cesarean Section, states that ‘external cephalic version for breech presentation is not contraindicated in women with a prior low transverse uterine incision who are at low risk for adverse maternal or neonatal outcomes from external cephalic version and TOLAC’ (Vaginal birth after previous cesarean delivery. Practice Bulletin No. 115. American College of Obstetricians and Gynecologists. Obstet Gynecol 2010;116:450–63).
Although adding in a thoughtful manner to the available literature, the results of this study, in isolation or in combination with earlier work, fall short of transforming the current limited state of our knowledge on this topic. Women with a prior caesarean section who are considering an ECV should be advised of these limitations.