Abstract
Objective To compare the conversion rate of non-cephalic to cephalic
presentation in external cephalic version (ECV) with and without nitrous
oxide Design Retrospective cohort study Setting Single, tertiary care
institution between January 2016 an June 2017 Population Women with
singleton, term gestation ECVs identified via International
Classification of Diseases Clinical Modification diagnosis code with
breech or malpresentation. Pregnancies with preterm, multi-fetal
gestation, abnormal placentation, and rupture of membranes were excluded
Methods Logistic regression was performed to test whether nitrous oxide
was associated with successful conversion to cephalic presentation. Main
Outcomes The primary outcome was successful rate of conversion to
cephalic presentation. The secondary outcome was the rate of vaginal
delivery. Results During the study period, 167 women underwent ECV: 77
with nitrous oxide and 90 without nitrous oxide. Of the 77 women who
used nitrous oxide, 25 (32.5%) were successful and 17 of these women
delivered vaginally (68%). Of the women who underwent ECV without
nitrous oxide, 29 (32.2%) successfully converted and 21 of these
delivered vaginally (72%). After controlling for confounders, the use
of nitrous oxide had no clinically or statistically significant
difference on ECV success rates (OR 1.08, 95% CI 0.52-2.23). Conclusion
Nitrous oxide does not seem to affect conversion rate to cephalic
presentation in ECV. Further studies are needed to determine the impact
of nitrous oxide on women’s decision to undergo ECV and on patient
satisfaction and tolerability. Funding The authors received no financial
support for the research, authorship, or publication of this data.