The fate of implant after endoscopic injection of dextranomer/hyaluronic acid in vesicoureteral reflux: time to partial reabsorption and stabilization

Abstract

Vesicoureteral reflux (VUR) potentially leads to renal damage, scarring, and eventually end-stage renal disease. Endoscopic treatment is well tolerated in children, it has reduced costs, and it effectively prevents urinary tract infections (UTIs), while avoiding long term antibiotics use. With the aim to investigate the time needed to reach the stabilization of the dextranomer/hyaluronic acid (Dx/HA) implants and to identify cut-off heights to ensure the success of the procedure, the authors analyzed ultrasonographic (US) intra-operative appearance of the mounds following endoscopic treatment for VUR and repeated the measurements during serial postoperative evaluations. The final clinical goal would be to obtain an alternative parameter that might reduce the need for postoperative voiding cystourethrogram (VCUG). The authors selected all children treated for moderate-high grade VUR with renal scarring or repeated UTI under antibiotic prophylaxis and followed with regular time points for at least 1 year (time points 1, 3, 6, and 9 months). Endoscopic injection performed with double-HIT/STING technique was combined with US to determine the intra-operative mound height and to calculate reabsorption rate. Mound height was measured as the maximal vertical diameter of the mound visualized at the ureteral orifice. Based on postoperative VCUG findings, patients were divided in group A (success of the endoscopic treatment) and group B (persistence of reflux). Thirty patients aged 1-7 years, counting for 47 ureters, completed the protocol and were included in the analysis. Mounds height had a significant difference between A and B at all time points (P<0.005). However, height did not differ between 6 and 9 months in both groups. Percentage of reduction in A was significant from 1 to 6 months (P<0.005) but not onward, while in B, it was never significant. Ultimately, both groups had a comparable trend of reabsorption, with a complete stabilization achieved in 6 months and an overall reduction of approximately 22%. Following the endoscopic injection of Dx/HA, US mounds height was found to strongly correlate with VCUG, both intra-operatively and for months following the procedure. Compared with the available literature, the authors firstreport a fixed reabsorption rate, consistent with the results in animal modelsand a timeframe to achieve stabilization. The possibility to measure those parameters with US renders this approach useful in the clinical setting, and it justifies the reduced use of VCUG in the follow-up of endoscopic injection for VUR.