Local chemolysis of obstructive uric acid stone with 0.1 M THAM and 0.02% chlorhexidine.

We used a modified chemolytic solution by combining 0.1 M THAM (tris[hydroxymethyl] aminomethane) with 0.02% chlorhexidine to treat 10 obstructive uric acid stone patients. A total of 23 local chemolysis sessions were performed. Five patients received 13 sessions (average: 2.6) as an adjuvant chemolysis after extracorporeal shock wave lithotripsy 5 patients received 10 sessions (average: 2) as a primary treatment. The average time of local chemolysis was 2.3 days, ranging from 1 to 4 days. In the 23 local chemolysis sessions, only one patient developed two episodes of fever (8.7%), which were managed successfully by conservative treatment. The mean values of effective renal plasma flow of treated kidney was increased from 108.2 to 155.6 ml/min (p < 0.05). The stone-free rate assessed by IVP and ultrasonography at 3 months follow-up was 80%. Our results indicate that the combined use of 0.1 M THAM and 0.02% chlorhexidine is an effective and safe method to treat obstructive uric acid stones.