Purpose: We compared the efficacy and safety of multiple session 99% ethanol sclerotherapy to single session OK-432 sclerotherapy for the treatment of simple renal cysts. Materials and Methods: Between September 2004 and November 2006, 41 patients (50 cysts, group 1) underwent sclerotherapy with 99% ethanol at least twice and 48 (61 cysts, group 2) underwent a single session of OK-432 sclerotherapy. Followup was performed with ultrasound or computerized tomography every 3 months for 1 year. Complete regression of the renal cyst or more than 70% reduction with no symptoms was considered successful treatment. Results: There was no significant difference in the mean size of renal cysts between the 2 treatment groups. The overall success rate was 84.0% in group 1 and 98.4% in group 2. For cysts smaller than 500 ml there was a similar complete regression rate between the 2 groups whereas in cysts 500 ml or larger the complete regression ratio of group 2 was higher than group 1. The symptom relief rate of group 2 was higher than group 1. In group 1 there were 2 patients with a recurrent cyst but in group 2 there was no enlargement of the aspirated cysts. For cysts smaller than 200 ml neither treatment group had complications whereas in cysts 200 ml or larger the frequency of complications was higher in group 1. Conclusions: Single session OK-432 sclerotherapy is simpler, safer and more effective than multiple session 99% ethanol sclerotherapy for the treatment of simple renal cysts, especially large cysts.
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