Renal Arterial Doppler Resistive Index in Differentiating Obstructive and Non-Obstructive Hydronephrosis in Children at Tikur Anbessa Specialized Hospital, Ethiopia, October, 2018

Abstract

BACKGROUND: Most congenital anomalies of the urinary tractpresent with hydronephrosis. Some are physiological while otherspathological. Ultrasound, micturating cyst urethrography, dynamic renalscintigraphy, intravenous urography, dynamic and static magneticresonance urography are used for examination. Currently, renal arterialDoppler resistance index is used as complimentary mechanism. This studyassesses our experience in resistive index measurement in differentiatingobstructive from non-obstructive hydronephrosis in children.METHODS: A cross-sectional study of forty-two infants and children(<14 years) with hydronephrosis were enrolled using consecutivesampling. Ultrasonography to assess the degree of hydronephrosis andavoiding cystourethrogram were used for the diagnosis of vesicoureteralreflux and posterior urethral valve. Intravenous urogram and surgerywere used to confirm causes for obstructive hydronephrosis. Dopplerultrasonography assessed both kidneys to determine mean resistive indexfor both obstructive and non-obstructive hydronephrosis as well as non-obstructive kidneys. Independent t test was used for analysis at p< 0.005.RESULTS: The major cause for obstructive hydronephrosis was pelvi-uretheric junction obstruction (47.6%) followed by posterior urethralvalve (16.7%). For non-obstructive hydronephrosis, vesicoureteral refluxwas the main cause followed by prune belly syndrome. The mean resistiveindex for non-hydronephrotic kidneys was 0.6654 ±0.053, for non-obstructive hydronephrotic ones was 0.6825 ± 0.06668 and obstructiveones was 0.7791 ± 0.11977. The mean resistive index difference betweenthe obstructive and non-obstructive hydronephrosis was 0.09661 withstandard error of difference 0.02443. The difference was statisticallysignificant (P-<0.001). A mean RI ROC curve showed sensitivity,specificity and accuracy of 71.1%, 81.2%, 75.4% respectively (p=0.003).CONCLUSION: This study has shown that the mean renal arterialresistive index was significantly higher in obstructive hydronephrotickidneys than non-obstructive hydronephrotic kidneys. This can be avaluable tool for diagnosis and follow-up after intervention.