Fetal Renal Volume and Fetal Doppler in Normal and Growth Restricted Fetuses: Is there a Correlation?

Manal Mohamed El Behery,Moustafa A Ibrahiem

doi:10.4172/2161-0932.1000118

Abstract

Objective: To evaluate if umbilical, middle cerebral and fetal renal artery Doppler could affect fetal kidney volume in healthy and growth restricted fetuses after 26 weeks of gestation. Design: A prospective cross sectional study. Setting: Obstetrics& Gynecology department, Zagazig University, Egypt. Sample: One hundred ten pregnant women, 77 with normal fetal growth parameter, and 43 with IUGR fetuses. Methods: Fetal renal volume, combined and relative kidney volume were measured using 2-dimensional ultrasound. Umbilical, middle cerebral artery and fetal renal artery Doppler indices were examined. Main outcome measures: Correlation of Doppler parameter to fetal kidney volume, and association of fetal biometric indices to combined fetal kidney volume. Results: Combined and relative fetal kidney volume was significantly reduced in growth restricted fetuses than in normally grown fetuses 29% (95% CI, 18%-37%), for the former and 18% (95% CI, 3%-22) for the latter. All fetal biometric indices were positively associated with combined kidney volume. The largest effects were found for estimated fetal weight and abdominal circumference after adjustment for gestational age. No correlation exists between umbilical or middle cerebral artery Doppler and fetal renal volume. A significant negative correlation was found between fetal renal artery pulsatility index and fetal renal volume after adjustment for abdominal circumference. Conclusion: Increased fetal renal artery pulsatility index in growth restricted fetuses is negatively correlated with fetal kidney volume with resultant decreased renal perfusion and impaired nephrogensis.

Highlights

Human fetal kidney development passes through a series of continuous and dependent changes to reach both morphological and functional maturity
Combined and relative fetal kidney volume was significantly reduced in growth restricted fetuses than in normally grown fetuses 29%, for the former and 18% for the latter
The largest effects were found for estimated fetal weight and abdominal circumference after adjustment for gestational age

Summary

Introduction

Human fetal kidney development passes through a series of continuous and dependent changes to reach both morphological and functional maturity. The final number of nephron, on average 1 million per kidney, is defined at birth, in term newborn. Several factors can modulate nephrogensis including maternal malnutrition, maternal hyperglycemia, Intrauterine Growth Restriction (IUGR), vitamin A deficiency, and fetal exposure to drugs [1]. Human studies showed a lower kidney weight with a reduced number of nephrons in low birth weight infants and growth restricted fetuses at birth [2,3]. In vivo studies of kidney size in human fetuses of known gestational age have shown that intrauterine growth restriction is accompanied by decreased kidney volume compared to fetuses with appropriate weight for gestational age [4,5]. As fetal kidney weight cannot be measured in utero. Renal volume measured by ultrasound is a valid substitute [6]

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Results

Conclusion