OP12.04: Umbilical vein blood flow in monochorionic twin pregnancies affected by selective fetal growth restriction

Selective fetal growth restriction (sFGR) is one of the possible complications of monochorionic twin (MC) pregnancies. The severity of the clinical course is determined by the difference in the proportion of placental parts and by the presence and type of placental anastomoses. As the genetic potential for growth should be the same, the differences in nutrient supply should explain the disproportionate size of the fetuses. The intraabdominal portion of the umbilical vein is an anatomically well-defined location, where fetal blood flow can be measured. The aim of this study is to analyse the differences in the umbilical vein parameters during pregnancy in MC twins affected by selective growth restriction and healthy controls. We have prospectively collected data from MC diamniotic pregnancies examined in our tertiary perinatal centre from January 2017 to March 2019. Serial ultrasound measurements were taken every 14 days from registration till delivery, miscarriage or fetal intervention (cord occlusion or LASER). Estimated weight (EFW) and commonly used Doppler parameters were measured by every visit. The diameter of intraabdominal part of the umbilical vein and the maximum velocity (Vmax) were also evaluated. Blood flow (BF) was calculated from Vmax and the vein diameter. We included 216 pregnancies. SFGR was diagnosed in 64 cases. Percentile graphs were built from gathered data for umbilical vein parameters. Panel regression with random effects was used for evaluation of differences in the parameters. Significant differences of umbilical vein diameter (p < 0.001 and in the BF (p < 0.001) was observed in fetuses with and without sFGR. The BF normalised for estimated weight of the fetus shows also significant differences in both groups (p < 0.01). Umbilical vein parameters seem useful in evaluating MC affected by sFGR. Our percentile graphs implicate a possibility of sFGR prediction based on umbilical vein parameters. Further analysis of reached data will be done. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.