Late obstruction after subureteral collagen injection

We present a case with distal ureteral obstruction after a single subureteral collagen injection. Postnatally, the girl presented with bilateral vesicoureteral reflux (VUR). At one year of age, a bilateral subureteral collagen injection was carried out. Postoperatively, the girl was followed up regularly and showed no pathological findings. But three years later, hydronephrosis with a distal ureteral obstruction on the right side was found. An ureteral reimplantation was performed on that side and the histological finding was a ureteral stenosis, consisting of collagen with a knotty sclerosis and a histiocytic and granulomatous reaction. This is the first case with a late obstruction at the ureteral orifice three years after a single collagen injection. We found an inflammatory reaction against the collagen, which led to a sclerosis of the implant. Further surveillance of patients after subureteral injections should focus on this kind of complication.