Clinical Value Of Ultrasound In Evaluating Renal Arterial Blood Flow And Renal Volume In The Second Trimester

Objective:Ultrasound was used to measure the parameters of renal volume（RV）and renal artery（RA）hemodynamics in the second trimester,and the normal reference value range of the two was established.To compare the differences in RV and RA blood flow between fetuses with abnormal kidneys and fetuses with normal kidneys of the corresponding gestational age.The correlation between RA hemodynamic parameters and RV and gestational age,RA hemodynamic parameters of antenatal hydronephrosis（AHN）and multicystic dysplastic kidney（MCDK）fetuses,RV and amniotic fluid volume were studied.To explore the clinical value of assessing fetal RV and RA blood flow in the second trimester.Methods:1.From October 1,2020 to October 1,2022,the data of 394 singleton pregnant women in the First Affiliated Hospital of Gannan Medical University were prospectively collected.The gestational age was 22-26⁺⁶ weeks,and the age of pregnant women was 20-45 years.Among them,the normal fetus was the normal group,a total of 323 cases;Those with fetal renal abnormalities were classified into the abnormal group（71 cases）.2.Using color Doppler ultrasound diagnostic instrument,standardized prenatal ultrasound system was performed on the fetus.The hemodynamic parameters of fetal RA and renal length（RL）,renal thickness（RT）,and renal width（RW）were measured by two-dimensional ultrasound.RV was estimated using the ellipsoid volume formula（ellipsoid calculation formula=RL×RT×RW×π/6）.Bilateral fetal RA blood flow was visualized by color Doppler ultrasound,and fetal RA hemodynamic parameters were measured:peak systolic velocity（PSV）,end diastolic velocity（EDV）,pulsation index（PI）PI),resistance index（RI）,and peak systolic to end diastolic flow velocity（S/D）.3.In order to obtain the reference ranges of RV and RA blood flow related parameters in normal fetuses at different gestational weeks in the second trimester,the normal fetuses were divided into two subgroups according to gestational weeks for data processing and comparative analysis,one group was 22-23⁺⁶ weeks,the other group was 24-26⁺⁶weeks.4.The data were statistically analyzed,and the measurement data were expressed as（x±s）.For data conforming to normal distribution,the 95%reference values were calculated using the normal distribution method.Paired t test was used to compare the renal parameters between the left and right kidneys of the same fetus.Independent sample t test was used to compare the renal parameters between normal fetuses and hydronephrosis fetuses at the corresponding gestational age.The correlation between RA hemodynamic parameters,RV and gestational age was analyzed by Pearson.Spearman correlation analysis was used to analyze the correlation between RA hemodynamic parameters,RV and amniotic fluid volume in AHN and MCDK fetuses in the abnormal group,and the test level wasα=0.05.5.Follow up was conducted for the fetuses with renal abnormalities.Detailed records were made for the cases of fetal renal abnormalities confirmed by delivery or induction of labor in our hospital.Results:1.Ultrasound detected 71 cases of fetal renal abnormalities,including AHN in 43 cases,MCDK in 13 cases,renal agenesis in 5 cases,ectopic kidney in 4 cases,simple renal cyst in 4cases,horseshoe kidney in 2 cases.In the abnormal kidney group,unilateral renal lesions were more common than bilateral renal lesions.All were confirmed by induction of labor or examination after delivery.2.There were no significant differences in the hemodynamic parameters of RV and RA between the left and right kidneys of the fetus in the normal group（P>0.05）.3.In this study,the reference ranges of RL,RT,RW and RV of normal renal fetuses at 22-23⁺⁶ weeks of gestation were（2.63±0.28）cm,（1.27±0.16）cm,（1.50±0.17）cm and（2.65±0.62）cm3,respectively.The reference ranges of RL,RT,RW and RV in normal renal fetuses at24-26⁺⁶ weeks of gestation were（2.85±0.29）cm,（1.38±0.18）cm,（1.54±0.17）cm and（3.19±0.76）cm3,respectively.The reference ranges of hemodynamic parameters of RA in renal normal fetuses at 22 to 23⁺⁶ weeks of gestation are:PSV was（37.89±8.06）cm/s,EDV was（5.31±1.35）cm/s,S/D was（7.90±2.21）,PI was（2.10±0.29）,RI was（0.86±0.04）.The reference ranges of hemodynamic parameters of RA in renal normal fetuses from 24 to 26⁺⁶ weeks of gestation are:PSV was（40.18±8.68）cm/s,EDV was（5.49±1.86）cm/s,S/D was（7.48±2.43）,PI was（2.04±0.36）,RI was（0.85±0.05）.4.Fetal RA hemodynamic parameters and RV were significantly correlated with gestational age（P<0.05）.The correlation coefficients of fetal RA hemodynamic parameters（PSV,EDV,S/D,PI,RI）,RV and gestational age were 0.507,0.602,-0.319,-0.273,-0.366 and 0.372,respectively.5.Compared with the fetal kidneys of the normal group of the corresponding gestational age:the RV of AHN and MCDK fetuses in the abnormal group was greater than that of the normal group,and the difference was statistically significant（P<0.05）.There was no significant difference in hemodynamic parameters of RA between AHN fetuses in the abnormal group and the normal group at the corresponding gestational age（P>0.05）.There were significant differences in RA hemodynamic parameters between MCDK fetuses with abnormal gestational age and those with normal gestational age（P<0.05）.6.In this study,there was no significant correlation between the hemodynamic parameters of RA in AHN fetuses and amniotic fluid volume,RV and amniotic fluid volume（P>0.05）.There was no obvious correlation between the hemodynamic parameters（PSV,EDV）,RV and amniotic fluid volume of MCDK fetal RA（P>0.05）,and the hemodynamic parameters S/D,PI and RI were negatively correlated with amniotic fluid volume,and the correlation coefficients were-0.975,-0.823 and-0.975,respectively.Conclusion:1.Ultrasound can measure the volume of fetal kidney and renal artery hemodynamic parameters,providing a more comprehensive imaging basis for evaluating fetal kidney growth and development.2.There is no significant difference in the volume of the left and right kidneys and the renal artery blood flow of the left and right kidneys during normal middle pregnancy.The hemodynamic parameters of RV and RA vary with gestational age.3.Fetal mild hydronephrosis has no obvious effect on fetal renal artery blood flow parameters,which can be followed up and observed without clinical treatment;In severe hydronephrosis,ultrasound measurement of RA parameters,combined with amniotic fluid volume,is meaningful for clinical assessment of pregnancy prognosis.4.The blood flow parameters of MCDK fetal RA are abnormal,and the greater the RA resistance index,the less amniotic fluid volume.The prognosis and prenatal intervention of MCDK fetal renal arterial blood flow parameters measured by clinical transport combined with ultrasound can be evaluated.