Z-score Analysis Of Normal Fetal Umbilical Vein Diameter And Blood Flow In The Second And Third Trimester Of Pregnancy

Objective: To establish the linear regression equation,percentile reference ranges and z-scores reference ranges for normal fetal umbilical vein diameter and blood flow in different segments(D-PUV,D-FUV,D-FIUV,Q – PUV,Q-PUV,Q-FUV,Q-FIUV)during the second and third trimester of pregnancy,as a quantitative indicator for clinical assessment of fetal intrauterine growth situation.Methods: The study population was 668 normal fetuses of 18-38 weeks gestation at the second xiangya hospital of the central south university from 2016 to 2018.Color Doppler ultrasound was used to perform the fetus for structural abnormality and functional disease.Measuring fetal biometric parameters included Biparietal diameter(BPD)and femur length(FL),and calculated gestational age(GA)based on menstrual age,and the fetal weight was estimated automatically according to the ultrasonic instrument software.The different segments of umbilical vein,which included pedicel of umbilical vein(PUV)and free loop of umbilical vein(FUV)and fetal intra-abdominal umbilical vein(FIUV),the diameter was measured(When the umbilical vein cross-section is circular,the maximum value is measured using the inner edge to inner edge measurement method).The umbilical venous blood flow waveform was recorded in the same part,the mean velocity was measured and blood flow volume(Q)was calculated.Gestational age(GA),Biparietal diameter(BPD),femur length(FL)as the independent variable,D-PUV,D-FUV,D-FIUV,Q – PUV,Q – FUV,Q-FIUV as the dependent variable,and analyze the relationship between them with the regression analysis.Then,with the linear regression equation to calculate z-scores reference ranges.Paired sample t-test was used to compare the diameter and blood flow of umbilical veins(PUV,FUV,FIUV)in three differentgroups.P<0.05 was considered statistically significant.Reliability-related analysis was performed on the measured values among examiners and examiners.Results: Normal fetal umbilical venous diameter and blood flow(D-PUV,D-FUV,D-FIUV,Q – PUV,Q-PUV,Q-FUV,Q-FIUV)and independent variable(GA,BPD,FL)has a good linear relationship,P<0.05 was considered statistically significant.The Z-score range of normal fetal umbilical vein diameter and blood flow is between-2 and +2.The PUV,FUV and FIUV in the middle and late gestation period were compared between D-PUV>D-FUV>D-FIUV,P<0.05,the difference was statistically significant;Q-PUV>Q-FUV,Q-PUV >Q-FIUV,P<0.05,the difference was statistically significant;Q-FUV compared with Q-FIUV,P>0.05,the difference was not statistically significant.Fetal intra-abdominal umbilical vein as measure of umbilical vein blood flow better stability.Conclusion: Z-score reference for umbilical vein diameter and blood flow is a quantitative indicators for fetal intrauterine growth.The diameter and the blood flow volume in umbilical venous increased as pregnancy progressed.The fetal umbilical vein blood flow is a stable spectrum during normal and late pregnancy.The blood vessel diameter decreases from PUV to FIUV.PUV shows a higher umbilical vein blood flow than FUV and FIUV.There was no significant difference in flow,free loop of umbilical vein and fetal intra-abdominal umbilical vein.