Comparison of echo-enhanced ultrasound with fluoroscopic MCU for the detection of vesicoureteral reflux in neonates

BACKGROUND: Fluoroscopic micturating cystourethrography (MCU) is used for screening and grading of vesicoureteral reflux (VUR). It involves ionizing radiation. This study was designed to assess the efficacy of contrast-enhanced sonography in predicting the presence or absence of VUR. OBJECTIVE: To compare an ultrasound contrast agent for detection of VUR in at-risk infants, and to compare these findings with fluoroscopic MCU with the aim of determining whether echo-enhanced sonography could be used instead of fluoroscopic MCU to identify neonates who do not have VUR, thus avoiding the use of radiation in this group. MATERIALS AND METHODS: From August 1999 to August 2000, 97 neonates (69 male, 31 female), aged 28-90 days (mean 48 days), referred for MCU and renal ultrasonography for investigation of VUR were recruited consecutively. Echo-enhanced sonography using stabilized microbubbles was followed immediately by fluoroscopic MCU. VUR was diagnosed if transient hyperechogenicity appeared within the pelvicalyceal system or ureter. The mean number of micturitions was 2.7 (range 1-6). RESULTS: Reflux was detected in 19 kidneys (14 babies) by one or other technique. The findings were concordant in 181 kidneys (94.2%). Echo-enhanced sonography had a sensitivity of 64% (95% CI 35-87%), a specificity of 100% (95-100%), a positive predictive value of 100% (66-100%), and a negative predictive value of 94% (87-98%). CONCLUSIONS: The role of echo-enhanced sonography is limited at present in our neonatal population as a screening examination. Its ability to detect cases of high-grade reflux may make it an attractive alternative in follow-up of known cases of VUR, and may help to reduce radiation exposure in this group.