Fetal Renal Volume and Fetal Renal Artery Doppler in Normal and Intrauterine Growth Restricted Fetuses

Abstract

Intrauterine growth restriction (IUGR), which is defined as less than 10 percent of predicted fetal weight for gestational age, may result in significant fetal morbidity and mortality. It is associated with a perinatal mortality rate that is 6 to 10 times higher than that for normally grown fetuses. The cause of IUGR is multifactorial and complex, including intrinsic fetal conditions as well as maternal and environmental factors. Placental insufficiency is the most common cause and it is associated with raised placental blood flow resistance. Only recently, researchers have focused on the long term morbidity that is associated with this condition. Provocative epidemiologic studies have suggested that IUGR is a risk factor for the development of essential hypertension and hyperlipidemina in later life. The actual pathways by which IUGR could lead to hypertension in adult life are unknown but several plausible theories have been put forward. Among the various theories, that of congenital oligonephropathy proposed by Brenner et al. is the premise of this study. In 1993, Brenner and Chertow postulated that  Summary   127  IUGR may cause congenital oligonephropathy. In essence, this theory proposes that IUGR may lead to impaired renal growth and development, with a subsequent decrease in nephron number and glomerular filtration surface area. Ultimately, this may result in both systemic and glomerular hypertension and acquired glomerular sclerosis with further increase in systemic blood pressure. As fetal kidney weight cannot be measured in-utero, renal volume measured by ultrasound is a valid substitute. With the latest new developments in the field of three– dimensional ultrasonography, accurate assessment of the fetal organ volume has become feasible and this technique has gained widespread application in different medical fields. Numerous investigators have demonstrated that three-dimensional ultrasonography is superior to twodimensional ultrasonography in fetal organ measurement. In this study we aimed to compare between fetal renal volume using 3D ultrasound (VOCAL) and fetal renal artery Doppler in intra-uterine growth restricted fetuses and fetuses who have normal growth in order to detect the accuracy of fetal renal volume as a diagnostic test for intrauterine growth restriction.  Summary   128  Our study was performed on two groups, group B: women within normal range fetal biometry i.e. control group (group B, n=21) and group A: women with intrauterine growth restricted fetus (group A, n=21), the mean renal volume was significantly lower in group B compared to group A (8.8± 1.6 in group A vs 5.7± 1.4 in group B, p< 0.05). There was statistically significant strong positive correlation between efwt and renal volume in all groups, in the IUGR group (p value <0.0001) (correlation coefficient: 0.96), while in the non IUGR group (p value <0.0001) (correlation coefficient 0.94). There was highly significant difference between UA RI and UA PI between the two groups (p<0.0001), there was no significance between RA RI and RA PI between the two groups