ABSTRACT
Objective:To establish the normal reference range of the ratio of fetal umbilical venous flow rate to umbilical artery pulsatility index (VAI).Methods:A total of 816 normal fetuses underwent prenatal examination and delivery were randomly selected from October 2018 to December 2020 in Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region. Fetal weight was obtained by measuring fetal biparietal diameter, head circumference, abdominal circumference, and femoral length.Umbilical venous flow (Quv) was measured. Umbilical artery pulsatility index (UA-PI) was obtained in the free segment of amniotic fluid. Quv was standardized according to fetal size to calculate the umbilical venous flow rate (nQuv) and VAI. The association between Quv, nQuv, UA-PI, VAI and the fetal gestational week were analyzed using correlation analysis. VAI was presented as ± s, the upper limit of 95% reference value and the lower limit of 5% reference value were taken as the standards of VAI increase and decrease, respectively. Twenty-six fetuses whose VAI were lower than limit of 5% and 20 fetuse whose VAI were than limit of 95% were chosed as the case group. Results:①Fetal Quv was positively correlated with gestational week ( r=0.893, P<0.001), nQuv and UA-PI were negatively correlated with gestational week ( r=-0.552, -0.827; all P<0.001), and VAI had no significant correlation with gestational week ( r=0.000, P=0.758); ②The mean, standard deviation, lower 5% reference value, and upper 95% reference value of VAI were 195.81, 55.61, 105.95, and 293.33, respectively; ③In the cases with abnormal VAI, 26 fetuses with reduced VAI, of whom there were 16 cases of maternal hypertension, and 13 cases complicated by severe preeclampsia; 1 case with 40 turns of umbilical cord torsion, 3 cases of stillbirth, 16 cases of preterm delivery, 19 cases of low neonatal birth body weight, 4 cases of 1-min Apgar score ≤7, 6 cases of umbilical artery blood pH<7.2, and 1 case without abnormalities in fetus during pregnancy and follow-up newborn. Among the 20 fetuses with increased VAI, there were 10 cases of fetal severe thalassemia, 2 cases of thalassemia, 1 case of sacrococcygeal teratoma, 1 case of portal venous shunt, 3 cases of placental chorioangioma, and 3 cases without abnormalities in fetus during pregnancy and follow-up newborn. Conclusions:The measurement and calculation of fetal VAI is simple and easy to perform. As a comprehensive index, fetal VAI remains constant in mid and late pregnancy, facilitates the follow-up of abnormal fetuses, and has potential clinical application.
ABSTRACT
Objective:To construct Z-score ranges for normal fetal middle cerebral artery peak systolic velocity(MCA-PSV).Methods:From May 2017 to October 2019, 865 normal singleton fetuses of 10th to 40th gestational weeks underwent prenatal ultrasound in the Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region. Using fetal biometric parameters as independent variables, and measurement of MCA-PSV on standard section as dependent variables, the regression analyses of the mean(M) and the standard deviation(SD) for each parameter were calculated separately and then the best fitting equation was selected. A group of diseases which might cause the abnormal MCA-PSV were assessed using these standards.Results:①Strong correlations were found between MCA-PSV and fetal biometric parameters ( r=0.935-0.939, P<0.001). ②Quadratic or cubic regression equations were fitted to the models of the means of the MCA-PSV, whereas linear equations were fitted to the SDs. ③In these case groups, intrauterine growth restriction, severe preeclampsia, intrauterine infection and homozygous α-thalassemia-1 demonstrated Z-score>2 reflective of increased MCA-PSV with varying degrees, especially with the homozygous α-thalassemia-1 fetus being the most significant (17/20, 85%). Conclusions:The calculation of Z-score for MCA-PSV as a function of fetal biometric parameters is intuitive and simple, it can be used as an important indicator especially for homozygous α-thalassemia-1.