Preoperative embolization of Wilms' tumors.

In two patients with Wilms' tumors, the ipsilateral kidney was nonfunctional. To facilitate initial surgical removal of the tumors, a preoperative transcatheter embolization was performed following diagnostic arteriography. Preoperative embolization of a renal tumor reduces the vascularity of the lesion prior to surgery, and a patient in whom primary surgical removal of the tumor would carry unacceptable risk may be converted into one in whom primary surgical removal is safe.