Renal Arterial Doppler Resistive Index in Differentiating Obstructive and Non-Obstructive Hydronephrosis in Children in TASH, Ethiopia, October, 2018.

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Addis Ababa University


Background: Most congenital anomalies of the urinary tract present with hydronephrosis due to several reasons. Some are physiological and others were pathological which persists for more than a year. Ultrasound, maturating cystourethrography, dynamic renal scintigraphy and intravenous urography , Dynamic and static MRU were used for examination. Currently renal arterial Doppler resistance index is not established as a clinically important diagnostic modality to differentiate obstructive and non obstructive hydronephrosis as observed in many conflicting research results. Objective: To assess the usefulness of Doppler ultrasound measurement of resistive index (RI) in differentiating obstructive from non-obstructive hydronephrosis in children. Methods: Forty two infants and children (<14 years) who were referred for the evaluation of hydronephrosis who fulfill inclusion criteria’s from November 1, 2017 to July 2018 were enrolled using consecutive sampling. Ultrasonography for the assessment of the degree of hydronephrosis and a voiding cystourethrogram were used for the diagnosis of the vesicoureteral reflux and posterior urethral valve .Intravenous urogram and surgery were used to confirm causes for obstructive hydronephrosis. Then Doppler ultrasonography was done for both kidneys of each patient to determine mean resistive index for both obstructive and nonobstructive hydronephrosis as well as non-obstructive kidneys. Their medical chart was removed. Independent t test was used for analysis and p< 0.005 was used to declare significance. Results were presented with text, tables and charts. Results: The study has included total of 42 children and 61 hydronephrotic kidneys. The major cause for obstructive hydronephrosis was PUJ obstruction accounting about 47.6% followed by posterior urethral valve 16.7%. For no obstructive hydronephrosis vesicoureteral reflux was main cause followed by prune belly syndrome. The mean resistive index of non -hydronephrotic kidneys was 0.6654 with SD of 0.053 non obstructive hydronephrotic kidneys 0.6825 ,SD 0.06668 and obstructive kidneys have mean RI of 0.7791 ,SD 0.11977. The mean resistive index difference between the obstructive and non-obstructive hydronephrosis was 0.09661 with standard error of difference 0.02443 .The statistical significance was tested with students independent t-test with P-<0.001 and 95% CI ( 0.0474 ,0.1457) .Using the cut-off iv point of 0.7 mean RI ROC curve was constructed and showed sensitivity ,specificity and accuracy of 71.1%,81.2% ,75.4% respectively (p=0.003). Conclusion and Recommendation: This study has showed mean renal arterial resistive index is significantly higher in obstructive hydronephrotic kidney than non-obstructive hydronephrotic kidney and can be potential valuable tool in resource limited countries to differentiate these conditions and as follow up tool after corrective surgeries .



hydronephrosis , Resistive index, Black Lion Specialized and referral hospital,children.