Aim: The present study aimed to assess the diagnostic efficacy of contrast-enhanced voiding urosonography (ceVUS) using SonoVue for evaluating duplex kidneys, and to compare it with fluoroscopic voiding cystourethrography (VCUG). Material and methods: Forty-six children with duplex kidneys confirmed by surgical intervention or cystoscopy were included in the study, resulting in a total of 46 duplex kidneys and 46 normal kidneys (138 pyeloureteral units). Results: The overall sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of RBUS for diagnosing duplex kidney disease were 73.91%, 80.43%, 79.07%, and 75.51%, respectively. The diagnostic performance of RBUS and ceVUS in detecting duplex kidney yielded an overall sensitivity, specificity, PPV, and NPV of 89.13%, 84.78%, 85.42%, and 88.64%, respectively. The sensitivity, specificity, PPV, and NPV of VCUG in diagnosing duplex kidney disease were 17.31%, 86.96%, 57.14%, and 51.23%, respectively. For the 42 pyeloureteral units with VUR, Cohen’s weighted kappa value for the agreement between ceVUS and VCUG in grading VUR was 0.702 (95% CI, 0.551 ~ 0.854; p <0.05). Conclusions: RBUS effectively diagnoses duplex kidneys with renal pelvic dilation, while ceVUS can further elucidate whether reflux occurs in the upper or lower moiety in cases of duplex kidneys with VUR. Compared to VCUG, both RBUS and ceVUS provide more intuitive diagnoses for duplex kidneys with VUR and ureterocele. Additionally, there is good consistency between ceVUS and VCUG in grading VUR. CeVUS is recommended as an initial evaluation method for patients suspected of having duplex kidneys associated with urinary tract infections.

duplex kidney; vesicoureteral reflux (VUR); contrast-enhanced voiding urosonography (ceVUS); voiding cystourethrography (VCUG); ureterocele