To evaluate the impact of placental anastomoses on the intrauterine growth of monochorionic (MC) twins.
A prospective study was conducted in a group of 53 MC twins. Intrapartally umbilical cords were clamped to identify placental sides corresponding to each twin. The postnatal dye injection technique was administered to evaluate vascular anastomoses, their number and type and visualize placental territory sharing patterns. Data from digital analysis were correlated with obstetrical follow-up.
Vascular anastomoses were revealed in 88.7% of cases. Arteriovenous (AV) anastomoses occurred in 75.4% and arterioarterial (AA) in 71.1% while venovenous (VV) in 26.4%. In the subgroup of MC twins without placental anastomoses, significantly higher birthweight difference and discordance were revealed when compared to MC twins without anastomoses (382.0 vs. 22 g; P = 0.03 and 49.14% vs. 16.02%; P = 0.03). On the other hand, in subgroups of MC twins with at least one AA anastomosis, twins’ birthweights were similar (p = ns) despite significantly higher placental territory sharing discordance (30.44% vs. 15.81%; P = 0.31).
Vascular anastomoses have a major impact on the intrauterine growth of MC twins. In certain cases, they may cause specific complications; however, in general, they regulate intertwin blood exchange and may compensate unequal placental territory.
Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.
Research funding: None declared.
Competing interests: Authors state no conflict of interest.
Informed consent: Informed consent was obtained from all individuals included in this study.
Ethical approval: This study was approved by the Bioethical Committee of the Medical University of Warsaw (consent number: KB/170/2017).
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