SUBURETERAL POLYDIMETHYLSILOXANE INJECTION VERSUS EXTRAVESICAL REIMPLANTATION FOR PRIMARY LOW GRADE VESICOURETERAL REFLUX IN CHILDREN: A COMPARATIVE STUDY HAMDY ABOUTALEB, STE ´ PHANE BOLDUC, JYOTI UPADHYAY, WALID FARHAT, DARIUS J. BA ¨ GLI AND ANTOINE E. KHOURY From the Division of Urology, The Hospital for Sick Children, Toronto, Ontario, Canada ABSTRACT Purpose: We compare the outcome of extravesical ureteral reimplantation to endoscopic poly- dimethylsiloxane (Macroplastique, Uroplasty, Inc., Minneapolis, Minnesota) subureteral injec- tion for primary low grade vesicoureteral reflux in children. Materials and Methods: Between 1997 and 2000, 180 patients underwent polydimethylsilox- ane injection (74, 108 ureters) or extravesical ureteral reimplantation (106, 166 ureters) for low grade vesicoureteral reflux. Low grade reflux was defined as grades I to III. Outcome analysis included success rates, de novo hydronephrosis, voiding efficiency, urinary tract infections and complications. Results: Mean patient age at surgery for the injection and surgery groups was 60 and 77 months, and mean followup was 12 and 15 months, respectively. Of the patients who underwent single injection 80.6% were cured of reflux at 3 months and 91.6% were cured at last followup. Success rate after reimplantation was 95.8% at 3 months which improved to 98.8% 1 year later. The success rate was significantly different between the injection and reimplantation groups at 3 and 12 months (p 0.01). Postoperative complications in the reimplantation group included transient urinary retention after bilateral surgery in 2 patients (3.3%), suprapubic fluid collec- tions in 2 and wound seroma in 1. No complications occurred in the polydimethylsiloxane group. Conclusions: Extravesical ureteral reimplantation has near perfect success with a low but definite complication rate. Polydimethylsiloxane offers high success rates for reflux in an ambu- latory setting with no short-term complications. Currently, endoscopic polydimethylsiloxane injection is our preferred mode of therapy for low grade vesicoureteral reflux in children when surgical correction is indicated. KEY WORDS: vesico-ureteral reflux, dimethylpolysiloxanes, injections, reimplantation, ureter The indications for surgical correction of low grade vesi- coureteral reflux are becoming exceedingly limited. 1, 2 Extravesical reimplantation, with its low morbidity and high success rate, has recently gained wider acceptance, with 99% reported success rate for low grade (I to III) reflux. 3, 4 On the other hand, endoscopic techniques have been reported as an alternative to standard surgical techniques and, although endoscopic subureteral injection has been reported as a min- imally invasive and efficient treatment for vesicoureteral reflux in children, 5 there remain concerns regarding the ideal material for injection. 6 The subureteral injection of polytet- rafluoroethylene was first reported in 1981 with success rates of 80% to 90%. 5 However, there are concerns regarding its safety and long-term efficacy. 7 Other injectable agents have been introduced including cross-linked collagen, polyvi- nyl alcohol and detachable balloons with many concerns re- garding efficacy or stability. 8 Polydimethylsiloxane is a solid silicone elastomer soft tis- sue bulking agent that has been suspended in a bio- excretable carrier gel. The carrier gel is water-soluble, low molecular weight polyvinylpyrrolidone hydrogel. The hydro- gel is later removed by the reticuloendothelial system and excreted unmetabolized. Upon injection, a local reaction to the substance occurs. Fibroblasts aid in collagen deposition between polydimethylsiloxane particles. 9 At our institution we have been using polydimethylsiloxane since 1997. In this study we compare the success rate of polydimethylsiloxane injection, a new injectable material, to extravesical reimplan- tation for primary low grade vesicoureteral reflux. MATERIALS AND METHODS Between 1997 and 2000, 10 boys and 64 girls (108 ureters) underwent subureteral endoscopic polydimethylsiloxane in- jection, and 30 boys and 76 girls (166 ureters) underwent extravesical reimplantation for low grade primary vesi- coureteral reflux at our institution. The surgery was per- formed depending on parental preference. Both options of intervention, with associated morbidities were explained to the family by a pediatric urologist. Low grade reflux was defined as grades I to III according to the International Reflux Study Classification. Patients with concomitant uni- lateral high grade reflux (grades IV and V) were excluded from the study. To account for the learning curve in mastering the poly- dimethylsiloxane technique, which was already acquired for the open surgery, we elected to exclude the first 6 months of our experience with the new injectable material. Initially, all children diagnosed with vesicoureteral reflux were assessed for dysfunctional voiding, defined as frequency, urgency, in- continence, constipation and dysuria. In addition, flow rate and post-void residual urinary volume assessment were ob- tained in select patients. To normalize bladder dynamics and decrease the severity of voiding dysfunction this evaluation was repeated semiannually in each case. Observational ther- apy with prophylactic antibiotics (trimethoprim plus or mi- Accepted for publication August 16, 2002. 0022-5347/03/1691-0313/0 Vol. 169, 313–316, January 2003 THE JOURNAL OF UROLOGY ® Printed in U.S.A. Copyright © 2003 by AMERICAN UROLOGICAL ASSOCIATION DOI: 10.1097/01.ju.0000040412.83051.90 313