THE URETEROVESICAL JET AS A FUNCTIONAL DIAGNOSTIC-TOOL IN CHILDHOOD HYDRONEPHROSIS

Childhood hydronephrosis (HN) is accurately detected by ultrasound (US ), but its functional work-up remains a domain of scintigraphy, the Wh itaker-test. and clinical follow-up. We utilized color doppler US (CD- Jet) of uretero-vesical jets (UVJ) to visualize the postobstructive ur eteral flow in childhood HN. A total of 177 standardized CD-Jet were p erformed in 132 children aged 1 day to 14.9 years. Sixty-nine investig ations in 43 patients with unilateral HN were compared with a standard ized technetium 99m-mercaptotriacetylglycine nephrogram: in 10 infants both procedures were performed consecutively on the same day. UVJ wer e visible in 96% of all investigations. Ureteral obstruction resulted in absence of UVJ in 85% of examinations: in the remaining 15% the jet frequency was less than 10% observed in the contralateral control. Re sults are highly significant in both uretero-pelvic (P<0.00007) and ur etero-vesical lesions (P<0.00005, Wilcoxon test) and are reproducible in sequential investigations. In nonobstructive distal HN the jet freq uency averaged 70% of the unaffected side (P<0.05). In proximal lesion s it is equal. Jet evaluation in reflux nephropathy did not differ fro m controls. Compared with scintigraphy. CD-US identifies obstruction w ith a specificity of 94.2% and sensitivity of 94.8%. CD-US of UVJ ther efore may serve as a reliable screening parameter in unilateral childh ood HN.