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

The authors studied the preoperative Technetium 99m-dimercaptosuccinic acid renal scan (DMSA) of patients undergoing unilateral vesicoureteral antireflux surgery to compare the amount of renal scarring between the refluxing and the contralateral renal units. They sought to determine whether postoperative contralateral vesicoureteral reflux was preexistent or new onset.

Sixty-eight patients who underwent unilateral vesicoureteral antireflux surgery and had preoperative DMSA and postoperative voiding cystourethrography (VCUG) examinations were studied. Preoperative DMSA results were analyzed to determine the amount of renal scarring in each kidney.

Sixty-four (94.1%) ipsilateral refluxing renal units had renal scars. Of the 68 contralateral renal units, scars were noted in 28 (41.2%). The rate of nonscar was 4 of 68 (5.9%) in reflux kidneys, which was significantly lower than 40 of 64 (62.5%, excluding 4 with a history of resolved reflux) 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 contralateral reflux, and 1 of them had a history of resolved reflux. Of the 6 contralateral kidneys with severe scarring involving 3 poles or contracted, 4 of 6 (66.7%) had subsequent reflux.

Scar in the contralateral kidney seen on DMSA scan seems to predict contralateral reflux after unilateral antireflux surgery. The contralateral reflux may be preexistent. Postoperative VCUG should be performed routinely for patients who have contralateral renal scars. In patients with a history of contralateral reflux or severe contralateral renal scar, simultaneous contralateral ureteral reimplantation should be considered.