Application Of Ductus Venosus Pulsatility Index For Veins And Nuchal Translucency During The First Trimester Of Pregnancy To Predict Twin-to-twin Transfusion Syndrome

Objective: To explore the possibility of ductus venosus pulsatility index for veins(DV-PI)inconsistencies between monochorionic twins in early pregnancy to predict twins transfusion syndrome(TTTS).To explore the significance of DV-PI inconsistencies between twins and nuchal translucency(NT)inconsistencies in early prediction of TTTS.Methods: The monochorionic twins were collected from the ultrasound department of Shengjing hospital of China medical university from January 2017 to June 2019 for routine examination of fetuses in early pregnancy at 10-13+6 weeks.The TTTS criteria for prenatal ultrasound diagnosis in the guidelines of the International Society of Ultrasound in Obstetrics and Gynecology(ISUOG)were used as the grouping criteria,the monochorionic twins were divided into the normal group and the TTTS group,among which the normal group had no other fetal structural deformities.Nuchal translucency(NT)and venous catheter flow spectrum were measured and recorded in all the enrolled twin cases of monochorionic twins during early pregnancy according to the requirements of ultrasound scanning specification for fetuses in early pregnancy,and the collected data were retrospectively analyzed.DV-PI is obtained through the automatic measurement function of the instrument.According to the numerical value,NT is divided into larger NT(nt-large)and smaller NT(nt-small),while DV-PI is divided into DV-PI(DV-PI large)and smaller DV-PI(DV-PI small).The value of NT difference between twins was calculated as NT large-NT small,and the value of DV-PI difference between twins was calculated as DV-PI large-DV-PI small.Between twins,NT and DV-PI were not expressed as percentages,respectively(NT large-NT small)/NT large ×100%,(DV-PI large-DV-PI small)/ DV-PI large ×100%.The non-normal distribution measurement data were represented by the median,and the Mann Whitney U test was used to compare the differences between groups,P < 0.05 was considered statistically significant.The inconsistencies of NT and DV-PI were analyzed by using the receiver operating characteristic curve(ROC)which can predict the optimal prediction threshold of TTTS and its corresponding sensitivity and specificity.The Z test was used to compare the predictive value of AUC between the two predictors.Results: Of the final 60 single chorionic twins,48 were normal(80%)and 12 were TTTS(20%).The difference of DV-PI and NT between the normal group and the TTTS group was statistically significant(p < 0.05).ROC curve analysis showed that the AUC obtained by predicting TTTS by DV-PI difference ratio was 0.730(95% confidence interval 0.548-0.912),while the AUC obtained by predicting TTTS by NT difference ratio was 0.733(95% confidence interval 0.573-0.892).Z test showed no significant difference between the two aucs.The optimal prediction bound of DV-PI difference ratio is 15%,the sensitivity is 67%,and the specificity is 85%.The optimal prediction bound of NT difference ratio was 20%,the sensitivity was 58%,and the specificity was 87%.Conclusion: DV-PI and nuchal translucency of monochorionic diamniotic twins in early pregnancy have the application value of early prediction of TTTS.The difference ratio of dv-pi ? 15% and NT difference ratio ? 20% between twins in early pregnancy can be used as an index to predict the occurrence of TTTS in early pregnancy.The measurement of DV-PI of monochorionic diamniotic twins in early pregnancy is simple and easy to operate and allows quantitative evaluation of the venous catheter spectrum in monochorionic diamniotic twins during early pregnancy.