Contralateral reflux after unilateral ureteral reimplantation-preexistent rather than new-onset reflux

Purpose: The authors studied the preoperative Technetium 99m-dimercaptosucc inic acid renal scan (DMSA) of patients undergoing unilateral vesicouretera l antireflux surgery to compare the amount of renal scarring between the re fluxing and the contralateral renal units. They sought to determine whether postoperative contralateral vesicoureteral reflux was preexistent or new o nset. Methods: Sixty-eight patients who underwent unilateral vesicoureteral antir eflux surgery and had preoperative DMSA a nd postoperative voiding cystoure thrography (VCUG) examinations were studied. Preoperative DMSA results were analyzed to determine the amount of renal scarring in each kidney. Results: Sixty-four (94.1%) ipsilateral refluxing renal units had renal sca rs. Of the 68 contralateral renal units, scars were noted in 28 (41.2%). Th e rate of nonscar was 4 of 68 (5.9%) in reflux kidneys, which was significa ntly lower than 40 of 64 (62.5%, excluding 4 with a history of resolved ref lux) in nonreflux kidneys (P<.001). Of 40 contralateral nonscarred kidneys, 1 of 40 (2.5%) had subsequent reflux, which was significantly lower than 5 of 28 (17.9%) of scarred kidneys (P<.005). Six patients (8.8%) had contral ateral reflux, and 1 of them had a history of resolved reflux. Of the 6 con tralateral kidneys with severe scarring involving 3 poles or contracted, 4 of 6 (66.7%) had subsequent reflux. Conclusions: Scar in the contralateral kidney seen on DMSA scan seems to pr edict contralateral reflux after unilateral antireflux surgery. The contral ateral reflux may be preexistent. Postoperative VCUG should be performed ro utinely for patients who have contralateral renal scars. In patients with a history of contralateral reflux or severe contralateral renal scar, simult aneous contralateral ureteral reimplantation should be considered. Copyrigh t (C) 1999 by W.B. Saunders Company.