Contrast-enhanced voiding urosonography as an alternate means of assessing vesicoureteral reflux in pediatric renal transplant patients
Julie W. Cheng, MD, MAE, Lauren N. Nicassio, BS, Helen HR Kim, MD, Nicolas Fernandez, MD, PhD, Elizabeth Tang, MD, Mark Ferguson, MD, Mark P. Cain, MD.
Seattle Children's Hospital, Seattle, WA, USA.
BACKGROUND: Vesicoureteral reflux (VUR) occurs in up to 58% of the pediatric renal transplant population and can risk urinary tract infections and graft dysfunction. Voiding cystourethrogram (VCUG) is currently the gold standard exam used to diagnose VUR. However, fluoroscopic imaging results in radiation exposure that can be cumulative in pediatric renal transplant patients that can require lifelong repeat imaging. Contrast-enhanced voiding urosonography (CEVUS) has been previously reported to be a safe means of evaluating VUR in children as well as the renal transplant population but has yet to be compared against VCUG in pediatric renal transplant patients in the United States. The purpose of this study was to compare the use of CEVUS and VCUG in evaluating and aiding in the management of VUR in pediatric renal transplant patients.
METHODS: This study has been approved by the Institutional Review Board at our institution. Pediatric renal transplant patients age 18 years and younger were included. Retrospective review was conducted for patients that underwent VCUG or CEVUS to assess for transplant VUR from July 2019 through June 2021. Patients undergoing VCUG or CEVUS for other urologic conditions were excluded. Demographic information, reason for VUR evaluation, fluoroscopy time, and post-imaging complications.
RESULTS: There were 4 transplant patients that underwent VCUG and 5 transplant patients that underwent CEVUS during the study period. One patient from the VCUG group was excluded as his imaging study was completed to evaluate for posterior urethral valves. Median age was 7 years [5-18] for the VCUG group and 9 years [5-12] for the CEVUS group. Time from renal transplant to VUR evaluation was 0.5 years [0.5-2.5] VCUG vs. 1.25 years [1-8.5] CEVUS. Patients in both groups underwent VUR evaluation for urinary tract infections or irregular renal biopsy findings. Transplant VUR was identified in 100% of VCUG patients with median reflux grade 3 [1-5] compared to 80% of CEVUS patients with median reflux grade 4 [3-4]. Median fluoroscopy time was 18 seconds [18-48] with median dose area product 18.7 [4.4-606.5] uGy*m2 for VCUG compared to no fluoroscopy or radiation exposure for CEVUS. There were no post-imaging complications with infections or adverse reactions to instilled agents in either group.
CONCLUSIONS: Contrast-enhanced voiding urosonography can safely evaluate VUR in renal transplant patients while also reducing radiation exposure without affecting management and patient outcomes.
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