Clinical Research
Z-scores analysis of kidney volume in normal fetuses in second and third trimester
Jin Ying, Xu Ran, Zhou Qichang, Deng Yan, Zhou Jiawei, Zeng Shi
Published 2020-06-25
Cite as Chin J Ultrasonogr, 2020, 29(6): 483-488. DOI: 10.3760/cma.j.cn131148-20200109-00019
Abstract
ObjectiveTo explore the variation of renal volume with gestational age(GA), biparietal diameter(BPD), abdominal circumference(AC), femur length (FL) and the Z value calculation formula.
MethodsFive hundred and eighty singleton pregnancy women from 20th to 38th gestational weeks in Second Xiangya Hospital of Central South University were enrolled. Two dimensional ultrasound was performed to record fetal growth parameters and renal longitudinal, transverse, anteroposterior diameters. Renal volume was calculated using ellipsoid volume equation: Volume =6/π×length×width×thickness. Using GA, BPD, AC, FL as independent variables and renal volume as dependent variables, the regression analyses of the mean and the standard deviation(SD) for each parameter were calculated separately. The Z-scores were calculated by the formula: Z-scores=(actual measurements of renal volume-predictive value of renal volume)/SD of predictive value.
ResultsFive hundred and forty-three cases of normal singleton fetuses were involved.The left and right renal volume were increased along with GA, BPD, AC, FL. Quadratic polynomial regression equations were each fitted to the models(r=0.775, 0.771, 0.811, 0.738, P<0.001;r=0.747, 0.735, 0.754, 0.745, P<0.001, respectively). The SD increased with the increases of independent variables and could be modeled with a simple linear regression(r=0.146, 0.225, 0.071, 0.155, P<0.001;r=0.091, 0.157, 0.091, 0.123, P<0.001, respectively). Z-scores were calculated and proved normally distributed after Shapiro-Wilk test(P>0.05).
ConclusionsThe normal Z-score reference range of fetal renal volume is established to help assess the normal renal growth and identify fetal renal abnormalities.
Key words:
Ultrasonography; Fetus; Renal volume; Z-score
Contributor Information
Jin Ying
Department of Ultrasound, Second Xiangya Hospital, Central South University, Changsha 410011, China
Xu Ran
Department of Urology, Second Xiangya Hospital, Central South University, Changsha 410011, China
Zhou Qichang
Department of Ultrasound, Second Xiangya Hospital, Central South University, Changsha 410011, China
Deng Yan
Department of Ultrasound, Second Xiangya Hospital, Central South University, Changsha 410011, China
Zhou Jiawei
Department of Ultrasound, Second Xiangya Hospital, Central South University, Changsha 410011, China
Zeng Shi
Department of Ultrasound, Second Xiangya Hospital, Central South University, Changsha 410011, China
