Appearance of Dextranomer/Hyaluronic Acid Copolymer Implants on Computerized Tomography After Endoscopic Treatment of Vesicoureteral Reflux in Children

Purpose: With the increasing popularity of endoscopic treatment for vesicoureteral reflux in children, dextranomer/hyaluronic acid copolymer implants are more frequently detected on computerized tomography, which may lead to misinterpretation and unnecessary intervention. The objective of this study was to characterize the long-term appearance of dextranomer/hyaluronic acid copolymer implants on computerized tomography. Materials and Methods: We evaluated the hospital charts of 893 patients who had undergone dextranomer/hyaluronic acid copolymer injection for vesicoureteral reflux between July 2001 and November 2007 to identify those who underwent subsequent computerized tomography of the abdomen and pelvis. A total of 30 patients with ureterovesical junction stones served as the control group. Seven patients who proceeded to extravesical reimplantation after failed endoscopic treatment had dextranomer/hyaluronic acid copolymer implants explanted and microscopically evaluated. Results: Of 893 patients who had undergone endoscopic treatment for vesicoureteral reflux 17 (1.9%) underwent subsequent computerized tomography. A total of 33 dextranomer/hyaluronic acid copolymer implants were detected on computerized tomography, and were classified as low density (21) or high density (12). Median density was 22 HU (range 15 to 27) for low density implants and 193 HU (126 to 367) for high density implants. Radiograph of the kidneys, ureters and bladder, and fluoroscopy did not visualize high density implants. Neither gender, age at endoscopic treatment, vesicoureteral reflux grade, hydrodistention grade, injection volume, success nor second injection was associated with a high density implant. Only elapsed time between surgery and computerized tomography was associated with increased implant density (p = 0.02). Conclusions: Dextranomer/hyaluronic acid copolymer implants may be encountered on computerized tomography as low or high density lesions. History of vesicoureteral reflux and absence of hydronephrosis as well as hematuria should provide reassurance and prevent inappropriate intervention for misdiagnosed ureteral stones.