External cephalic version in nonvertex second twin-Success rate, mode of delivery, and safety: A systematic review

One of the key challenges regarding the management of twins involves choosing the optimal mode of delivery, which is strongly influenced by the final presentation of both fetuses. In cases of vertex-nonvertex pregnancies attempting the trial of vaginal delivery, external cephalic version (ECV) is one of possible management options. The main objective of this review was to collect and summarize available data in terms of the application of ECV in the population of nonvertex second twins.

Using the PRISMA guidelines, we searched for original, English-language studies investigating ECV in nonvertex second twins. The PubMed/MEDLINE, SCOPUS, and COCHRANE databases were searched until May 2024. Reviews, case reports, editorials, and conference papers were excluded from further analysis. Out of 260 papers retrieved, 10 were subjected to the final analysis in terms of success rates, modes of delivery, and adverse outcomes.

The total number of ECVs was 289, with an overall success rate of 64.4%. In the group of successful versions, vertex vaginal delivery was achieved in 171 cases (91.9%). The incidence of adverse maternal and neonatal outcomes was low.

The purpose of this review was to consolidate and update the current knowledge regarding ECV in nonvertex second twins. Based on the results of this series of studies, ECV appears to be a reasonable management option. However, it is important to highlight several significant limitations. The primary concern is the lack of recent research in this field over the past three decades, with the most recent study in our review being published in 1998. Furthermore, the actual number of studies addressing this topic is relatively low, characterized by a retrospective nature and questionable methodologies. These limitations make it challenging to draw definitive conclusions for clinical practice. This is an important message for our community, emphasizing the need for further studies in this area, particularly randomized controlled trials, to evaluate the safety and success rate of vaginal twin delivery after ECV when the second twin presents in a nonvertex position.