[Local treatment of obstructive uric acid calculi]

Dissolution of uric acid calculi could be obtained by oral or parenteral urinary alcalinization, but this method cannot apply to the case of obstructive calculi. Nineteen obstructive calculi in 18 patients were treated by in situ alcalinization through a percutaneous nephrostomy catheter (PCN). Eight patients were initially anuric, 7 of whom from an obstructed solitary kidney and 1 from a bilateral obstructive lithiasis. Fifteen calculi were located in the ureter, 3 in the uretero-pelvic junction and 1 in the pelvis. After 48 h of urinary diversion through PCN, an isotonic sodium bicarbonate solution (14 g %) was continuously infused at an average flow rate of 2.8 l/24 h, through either an unique PCN, or a 2 PCN-irrigation circuit in the 7 cases with permanently obstructive calculus. Fifteen calculi (80%) were completely dissolved after 3 to 13 days of alcalinization (average 5.8 days). One large calculus was reduced by 3/4 and further removed by percutaneous lithotripsy. Three patients underwent ureterotomy after 9 to 11 days of uneffective treatment. Local alcalinization is an effective and non invasive treatment for obstructive uric acid calculi, and is logically associated with the necessary urinary diversion.