Doppler sonography in congenital ureteropelvic junction obstruction and multicystic dysplastic kidneys

The accurate diagnosis of severe congenital ureteropelvic junction obstruction (UPJO) and the indications for surgical intervention are a matter of debate. Differential diagnosis from, for example, congenital cystic kidney malformations is important. In the present study we analysed the value of Doppler sonography (DS) for assessment of obstruction in congenital UPJO and its usefulness for differential diagnosis. A total of 138 infants and children were examined. Forty-three healthy infants and 24 children who had had a pyeloplasty at least 1 year previously served as control groups. Seventy-one children with UPJO and cystic kidney malformations underwent DS in addition to the usual examinations of intravenous urography and scintigraphy. Resistive Index (RI) was measured in both kidneys. Twenty infants showed decompensated UPJO and had needed an operation. Preoperatively all showed significantly increased RI (RI = 74%), which returned to normal after operation (RI = 68.3%). Thirty-nine children with UPJO could be managed conservatively, showing compensated obstruction on diuretic renography. On DS they had normal and symmetrical RI values (RI = 67%). Eleven children had multicystic dysplastic kidneys; 4 underwent nephrectomy. On DS all showed either absence of perfusion signals or very low flow velocities with very high RI values (RI = 90-100%) in the renal vessels. One child was found to be suffering from a cystic nephroma. DS was able to reveal quite normal vessel distribution in renal parenchyma with slightly elevated RI values (RI = 80%). Our results indicate that DS a non-invasive, non-ionising method of investigation, may serve as an additional functional parameter for defining accurately the degree of obstruction in UPJO.