Ureteral Obstruction After Endoscopic Treatment of Vesicoureteral Reflux: Does the Type of Injected Bulking Agent Matter?

Purpose of ReviewEndoscopic injection of bulking agents for the treatment of vesicoureteral reflux (VUR) has become a therapeutic alternative to antibiotic prophylaxis and ureteral reimplantation. Although considered as a safe and efficient procedure, several studies have reported cases of ureteral obstruction (UO) after endoscopic correction of VUR. This review article evaluates the present VUR literature to estimate the incidence of UO following endoscopic injection of different substances, while also discussing the impact of injection technique and implant volume.Recent FindingsTwenty-five publications were identified that provided detailed information on 64 females and 32 males (age range, 7months-48years) that developed UO after endoscopic treatment of VUR using dextranomer/hyaluronic acid (Dx/HA), polyacrylate polyalcohol (PP), polydimethylsiloxane (PDMS), calcium hydroxyapatite (CaHA), polytetrafluoroethylene (PTFE), or collagen. There was some variation in the reported incidence of UO among these materials: Dx/HA (0.5-6.1%), PP (1.1-1.6%), PDMS (2.5-10.0%), CaHA (1.0%), and PTFE (0.3%). Postoperative UO was described following subureteric transurethral injection (STING), intraureteric hydrodistension implantation technique (HIT), combined HIT/STING and double HIT. The injected volume ranged widely, also depending on the type of bulking agent: Dx/HA (0.3-3.0mL), PP (0.3-1.2mL), PDMS (1.0-2.2mL), CaHA (0.4-0.6mL), and PTFE (1.5-2.0mL). The timing of UO varied from immediately after the procedure to 63months. Over half of patients showed asymptomatic hydroureteronephrosis on follow-up imaging, whereas the remaining presented with symptoms of acute UO or fever.SummaryUO remains a rare complication after endoscopic correction of VUR, generally reported in less than 1% of treated cases, which appears to be independent of the injected substance, volume, and technique. However, long-term follow-up is recommended as asymptomatic or delayed UO can occur, potentially leading to deterioration of renal function.