In this study, the success rate of ECV was 71.7% and 84% of those mothers who had successful ECV had spontaneous vertex vaginal delivery. The variables that were significantly associated with the success of ECV were multiparty, thin abdominal wall, unengaged breech, posterior placenta, absence of pain during procedure, and soft uterine tone.
External cephalic version provides a means of reducing cesarean births, but an estimated 20–30% of eligible women are not being offered ECV (10, 11). The goal of ECV is to increase the proportion of vertex presentations among fetuses that were formerly in the breech position near term (12). According to the updated ACOG practice guidelines for ECV and based on a recent meta-analysis, the success rate of this procedure is reported to be 58 %( 13, 14). Similarly, according to the SOGC guidelines, the procedure results in a cephalic presentation in approximately 60% of the time (15). The recent RCOG recommends that women undergoing ECV should be informed that the success rate of ECV is approximately 50 %( 16).
Overall, ECV is not widely practiced in East, Central, and Southern Africa, mainly owing to concerns related to safety and policy (17). Findings of our study have revolutionized this reality and one of the highest rates of success of ECV has been observed. From 152 ECV cases analyzed, 109(71.7%) had successful ECV. This rate of ECV success in our study is higher than reports from different studies across most parts of the world. In a study done in Netherlands in 2015, among 2318 women having ECV procedure, 1093 (47.2%) women had successful ECV, which is lower than the finding in our study (18). Similarly, one of the largest data on success of ECV, a cross-sectional analysis of 51,001 cases of ECVs in the USA (from 2010 to 2014) documented only a 58.5% success rate (19). Another large prospective data from UK, in which 2614 women who underwent ECV were analyzed, showed a 47 % ECV success rate (95% CI 47.0 -50.9%)( 20 ), which is smaller than the finding in our study, and comparable to a finding of 45.3% success rate from a retrospective cohort study of 287 cases of ECV in Israel(21) and a Malaysian report of 51.4 % success rate found in a recent retrospective review of 142 cases (22). A retrospective cohort study from Israel, done in 2019, in which 250 ECVs were analyzed showed a success rate of 64.8 %( 23), which is again lower than that found in our study but higher than reports from other studies. Another recent study from Saudi Arabia reported a low success rate of 53.9%(24). Although there is scarcity of data on success of ECV in African settings, a 71.6% success rate found in our study is higher than findings from a prospective study done in Nigeria in which 111 ECV cases were studied and 74 (66.7%) of these were successful (25).
A possible explanation for this unique finding of higher ECV success rate in our study, compared to the reports from the afro-mentioned studies from around the world, could be difference in patient body habitus. Although, obesity among reproductive age group in Ethiopia is variable, it is lower than that reported from developed world. For example, the prevalence of overweight and obesity among reproductive age group in Addis Ababa, the city where in this study was conducted, is only 20.6 %(26). Majority(56.8%) of the women who had successful ECV in our study had weight less than 65 KG, which indirectly corresponds to lower rate of obesity. Morbid obesity has been found consistently to be associated with low ECV success rate in different studies (27).
In the literature, a variety of factors have been mentioned as predictors of ECV success. Earlier, Newman et al. found that parity, estimated fetal weight, breech station and placental implantation site were the most useful predictors of ECV success (28). In the present study, multiparous women had a 1.4-times higher probability of success than nulliparous women (95% CI, 0.07-2.35); thin abdominal wall had 3.5 fold increased success rate ( 95% CI, 0.29-42.40) ; unengaged breech had a 1.1 higher probably of success than engaged(95% CI, 0.26-4.74); a posterior location of placenta increased the success rate by 1.14 times compared with an anterior placenta (95% CI, 1.03–2.60); the odds of successful ECV was 14.68((95% CI, 1.65–34.97) when cases experienced no pain during the procedure ; and tense uterine tone was significantly associated with lower success rate as compared to soft tone (AOR= 0.08 ,95% CI, 0.016—0.39).
Most of the predictors of ECV success found in our study are consistent with reports from previous studies. For instance, P. A. Feyi-Waboso et al. found multiparty, flexed breech, unengaged breech, normal Amniotic fluid volume, and posterior placenta as favorable factors for successful ECV (25). Similarly, J. Burgos et al. from Spain found that the variables significantly associated with ECV success were parity, placental location, amount of amniotic fluid, and type of breech (29). Likewise, Melo et al and colleagues in their cohort study of 18 years’ experience, demonstrated that multiparty, low uterine tone and high liquor volume were predictor s of ECV success (20). Another recent Canadian study demonstrated that non-engagement of the presenting part and an easily palpable fetal head were independently associated with success of ECV (30).
Women with a cephalic-presenting fetus at birth as a result of successful ECV are not at greater risk of obstetrical interventions at birth when compared with women with fetuses who spontaneously turn to a cephalic presentation in the third trimester (31). In this study, 84% of those mothers who had successful ECV had spontaneous vertex vaginal delivery, which is comparable to the finding of 85.7% vaginal delivery rate in a previous similar study from UK(20).
Strengths of this study include; prospective data and Sub-Saharan Africa study setting, where there is scarcity of data on experience and the finding of a higher ECV success rate. As discussed above, majority of ECV practice guidelines recommend to inform women that ECV has a success rate of 50-60 %. If substantiated with results from future studies, the finding of ECV success rate above this percentage in our study could challenge existing recommendations regarding ECV success rate and improve quality of ECV counselling for pregnant women complicated with breech presentation.