Abstract: This paper investigated the predictive value of conventional ultrasound indices combined with HD live technique in monochorionic (MC) twin pregnancy. Both conventional ultrasound examinations were performed in early pregnancy to obtain fetal conventional ultrasound indices[nuchal translucency layer (NT) thickness, crown-rump length (CRL)], and HD live technique to obtain ductus venosus (DV) spectral abnormalities and fetal cord abnormalities. The results showed that among 208 cases (416 fetuses) MC twin pregnancies, the fetal abnormality rate was 33.67% in MC double amniotic sac twin pregnancies and 58.33% in MC single amniotic sac twin pregnancies. The fetal abnormal group had higher inter-twin NT difference, CRL difference, DV spectrum abnormality rate and fetal umbilical cord abnormality rate in early pregnancy than the fetal normal group (P<0.05). In the early pregnancy the differences of NT, CRL, DV spectrum abnormalities and fetal umbilical cord abnormalities between twins were significantly associated with the occurrence of fetal abnormalities in MC twin pregnancy (P<0.05). The area under the curve (AUC) of NT differences, CRL differences, DV spectrum abnormalities and fetal umbilical cord abnormalities between twins in early pregnancy predicted the occurrence of fetal abnormalities in MC twin pregnancy alone were greater than 0.7, and the combined predicted AUC was the largest (0.922). The anatomical relationship of the HD live technique for examining MC twin pregnancies showed stereoscopic visualization, and it has good application value for predicting fetal anomalies in MC twin pregnancies when combined with conventional ultrasound indices.

Key words: monochorionic twin pregnancy, ultrasound, HD live technology, fetal abnormalities, prediction