Voiding urosonography and voiding cystourethrography in primary vesicoureteral reflux associated with mild prenatal hydronephrosis: a comparative study

Background Contrast-enhanced harmonic voiding urosonography has been introduced as a sensitive, radiation-free imaging method for the diagnosis of vesicoureteric reflux. Objective To evaluate the occurrence/severity of vesicoureteric reflux in infants with mild prenatal hydronephrosis comparing voiding cystourethrography and voiding urosonography. Materials and methods Sixty infants with prenatal hydronephrosis were studied (anteri omicron posterior pelvic diameter 5-9 mm on ultrasound [US] at gestational weeks 21-30). Postnatal US was performed within the first month of life, as well as voiding cystourethrography and contrast-enhanced voiding urosonography at 1.5-2.5 months at the same session. Results Vesicoureteric reflux was diagnosed on at least one modality in 19/60 (32%) infants, and more often on contrast-enhanced voiding urosonography (18/60, 30%) than on voiding cystourethrography (8/60, 13%),P=0.046. Among girls, reflux was more often seen on contrast-enhanced voiding urosonography (6/16, 38%) than on voiding cystourethrography (1/16, 6%),P=0.03. Vesicoureteric reflux missed by voiding cystourethrography was more severe (Grades I, II and III in one, nine and four kidney-ureter-units, respectively), compared with a single case missed by contrast-enhanced voiding urosonography (Grade I in one kidney-ureter-unit). Conclusion In the absence of a reference standard, our results imply that voiding cystourethrography might underdiagnose reflux, and/or contrast-enhanced voiding urosonography may overdiagnose reflux.