OP10.02: The CHOP cardiovascular score: a method for quantification of cardiovascular abnormality in the twin–twin transfusion syndrome

Abstract

Objectives: Umbilical vein volume flow (UVVF), calculated as velocity (cm/s) times transversal section area at the straight portion of the intra-abdominal umbilical vein (cm2), is an interesting parameter to study in twin–twin transfusion syndrome (TTTS). Recipients were found to have 2 to 3 times higher UVVF than donors, but this parameter was not studied in normal monochorionic pregnancies. Methods: Comparison of recipient to donor (rec/don) UVVF ratio and bigger-to-smaller UVVF ratio in non-TTTS monochorionic twin pregnancies (control group). The method of dividing the same parameter from each pair of twins aimed to emulate other factors such as gestational age and maternal condition, which change between pregnancies. The control group consisted of monochorionic twin pregnancies with normal umbilical artery Doppler and normal amniotic fluid (2 to 8 cm of MVP), between 18 and 26 weeks. Results: Eight-four TTTS and 24 normal monochorionic twin pregnancies were compared. The median weight discordance was 1.3 (rec/don) and 1.2 respectively (big/small, Wilcoxon P < 0.7). The UVVF ratio between recipients and donors (UVVF R/D) was greater than that of the bigger to smaller UVVF ratio from normal monochorionic twins (medians 2.2 and 1.3, Wilcoxon P < 0.001). Conclusions: This study shows that UVVF R/D imbalance occurs in cases with the polyhydramnios and oligohydramnios sequence found in TTTS, and that normal monchorionic pregnancies lack this imbalance. The difference is not due to fetal weight discordance as it was shown that normal monochorionic twins had similar discordance. The parameter has still not proven to be useful in screening for early diagnosis by this methodology, but it describes that UVVF imbalance between twins does not exist in normal monochorionic pregnancies. OP10.02 The CHOP cardiovascular score: a method for quantification of cardiovascular abnormality in the twin–twin transfusion syndrome