[Urinary tract duplication]. / Duplicaciones del tracto urinario.

OBJECTIVES: Review the clinical and radiological characteristics of the different kinds of urinary tract duplications, assessing the outcome of the cases and the incidence of renal parenchymal injury. MATERIAL AND METHODS: A retrospective study was performed including 301 children diagnosed of renal duplication by urological ultrasound, voiding cystourethrogram (VCUG) and 99-technetium renal scintigraphy (DMSA). RESULTS: They were classified in four groups. The first consisted of 166 (55.1%) cases that had complete ureteral duplication without an obstructive component (CD). The cases that had an upper system obstruction due to an ectopic ureter (EU), 19 (6.3%), or an ureterocele (UTC), 35 (11.6%), were divided into two different groups. The fourth group 81 (26.9%) had incomplete ureteral duplication. The nephro-urological study was performed in 181/301 after a urinary tract infection; in 100/301 after a prenatal finding of hydronephrosis. It was a casual diagnosis in 20/301. The percentage upper kidney dilation in the diagnostic ultrasound was significantly higher in those with EU 16/19 (84%) and in those with UTC 33/35 (94%), compared with the upper pole dilations found in the CD 35/166 (21%) and ID 21/81 (25%). Surgery was performed in 96/166 (41%) of the CD, 7/81 of the ID, 16/19 (84%) of the EU, and 34/35 (97%) of the UTC. Three cases with EU and 8 with UTC needed a second surgery, and 3 a third one. No scintigraphy changes were observed in 58% of the patients in the CD group, 87% in the ID group, 29% in the EU group, and 5% in the UTC group. As regards the renal duplications who did not have surgery, it was found that there were 98 refluxing units in the CD, and 74 in the ID. The spontaneous resolution of the vesicoureteral reflux (VUR) was 80% in the CD, and 90% in the ID (McNemar test P<.001). The average healing time ranged from 1 year to 5 years (Mean: 3 years and 3 months). CONCLUSION: The patients with higher risk of having renal injury are those who presented with a duplication with upper kidney obstruction due to ectopic insertion of the ureter, particularly due to an ureterocele.