Detection of low-grade vesicoureteral reflux in children by color Doppler imaging mode

Abstract

Vesicoureteral reflux (VUR) is common in children with urinary tract infections (UTI) and may result in renal scarring or reflux nephropathy. To date, the primary diagnostic tool has been voiding cystourethrography (VCUG). A new technique for evaluation of grade 1 and 2 VUR is described using color Doppler imaging-mode cystography (CDIMC): 77 children, aged 7 months to 14 years, were examined for VUR by CDIMC and standard VCUG. According to the established reflux sonography (US) using a real-time mode, all patients selected for this study had a normal urinary tract on conventional gray-scale US. We studied 154 ureters, and a total of 31 were found to be refluxing on CDIMC and 30 on VCUG. A positive sonogram was defined as visualization of Doppler signals from the bladder to the ureter during the course of bladder filling. Taking VCUG as the gold standard, we had ten false-positive findings. The false-positive rate of 18.5% may have been due to the shorter observation time of fluoroscopy. Comparison of the two methods shows CDIMC to be 70% sensitive with a specificity of 92% in the detection of VUR grade 1 and 2. To evaluate the incidence of asymptomatic low-grade VUR in a non-infected population, a second series of 38 children (19 males, 19 females) aged 3 to 15 years (mean 8.8 years) with normal urologic status and urine cultures were studied by color Doppler imaging mode (CDIM) for detection of asymptomatic low-grade VUR. Four children were found to have a unilateral refluxing ureter. The incidence of VUR in children with a normal urinary tract and no prior UTI was 10.5%. In conclusion, CDIMC can be used as a possible alternative to standard VCUG for the screening and follow-up of low-grade VUR. In addition, our study indicates that asymptomatic grade 1 and 2 reflux might be a physiological condition.