Impact of power index, hydroureteronephrosis, stone size, and composition on the efficacy of in situ boosted ESWL for primary proximal ureteral calculi

Objectives. The efficacy, safety, feasibility, and outcome of in situ treat ment applied to select proximal ureteral calculi was assessed and analyzed with a view to avoiding auxiliary interventions and providing high clearanc e rates in the shortest possible time. We studied the impact of several cli nically important variables, including power index, degree of hydroureteron ephrosis (HDUN), stone size, and composition on the efficacy of sequential in situ boosted extracorporeal shock wave lithotripsy (ESWL) in a select gr oup. The power index requirement for the in situ boosted protocol and the i mpact of the stone size/composition, degree of HDUN, and clearance rates we re also analyzed. Methods. An in situ (no instrumentation) boosted protocol was applied to 13 0 primary unimpacted proximal ureteral calculi with no prior intervention. A typical session with the Siemens Lithostar Plus comprised 3000 shock wave s, in installments of 500, deployed at a power setting of 1 to 4 kV with a gradual stepwise escalation. Sequential boosted additional sessions of ESWL were administered on days 2, 7, and 14, tailored to the degree of fragment ation, clearance status, and amount of residual stone bulk. Several paramet ers (shock waves, kilovolts used, fluoroscopy time, number of sessions, sto ne size, composition, fragmentation, clearance, and HDUN) were recorded and the results analyzed statistically. Results. The results were excellent in 83.8%, with a mean duration to compl ete clearance of 11.3 days. In situ ESWL failed in 7.69%, and the auxiliary intervention rate was 10.7%. Pre-ESWL HDUN was present in 78.3%, the mean power index was 184.6/session/case, and the average stone burden was 8.9 mm (2). Calcium oxalate monohydrate was the most common stone (56%). Renal col ic was the most common side effect observed. The power index, fragmentation at the first session, and stone size were found to be the most favorable s ignificant variables affecting stone clearance. The degree of HDUN, number of sessions, and stone composition did not significantly impact the clearan ce rates. Conclusions. In situ boosted ESWL should be the first-line therapeutic moda lity in select unimpacted primary proximal ureteral stones. UROLOGY 58: 16- 22, 2001. (C) 2001, Elsevier Science Inc.