Purpose: Delayed drainage on isotopic diuretic renography (IDR) is an accepted sign of obstruction of upper urinary tract in adults and adolescents and remains the basic diagnostic tool despite some pitfalls. Some few reports have demonstrated the clinical usefulness of the analyze of ureteric jets by color Doppler ultrasonography (CDUS) in this situation.The object of this study was to determine the diagnostic accuracy of Color Doppler sonography in distinguishing obstructive and nonobstructive hydronephrosis by evaluation of ureteric jets(UJ).
Methods and Materials: We prospectively studied 42 adults and adolescents patients with hydronephrosis with grade II dilatation or bigger. All patients underwent diuretic renography and evaluation of ureteric jets under transverse CDUS of the bladder. The UJ evaluation were performed immediately after conventional sonography within 2 weeks of IDR. Obstruction was defined as a unilateral absence of the ureteric jet on CDUS and, in IDR as a half-time excretion greater than 20 minutes. We assumed that the contralateral UJ and pattern of drainage would be a good control since none of the patients had bilateral hydronephrosis. The results were compared, obtaining 2 x 2 tables to analyze specificity, sensibility, accuracy and the coefficient of agreement.
Results: There were 22 females and 20 males with ages between 17-64 years (mean 28.2). Ureteric jets were observed in all investigations. According to the findings of diuretic renography, 13 hydroneprotic kidneys were considered obstructed. In this group, 12 units presented as obstructive pattern without jets on CDUS. In hidronephrotic kidneys considered nonobstructed and contralateral units the UJ were observed in all cases. The presence of UJ differed significantly between obstructed and nonobstructed kidneys. (p< 0.001). Comparing both tests and considering the IDR as a gold-standard the analyze of UJ by CDUS has a 92.3% of sensibility, 100% of specificity, 97.6% of accuracy and the Kappa Index was 0.942. The strength of agreement is considered very good.
Conclusion: CDUS evaluation of ureteric jets is accurate in the differentiation of obstructed from nonobstructed kidneys and appears to be an effective parameter for evaluation and follow-up of unilateral hydronephrosis in this population.
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