The Medstone fixed, mobile, and modular configurations: Impact on efficacy

Purpose: To evaluate the efficacy of three lithotripter configurations that utilize the Medstone STS treatment head. Patients and Methods: From 1999 through 2002, 13,131 patients were treated with the Medstone STS fixed-site unit (STS-FIX; 52%), the mobile coach-transportable unit ( STS-MOB; 26%), or the modular operating-room unit ( STS-T; 22%). All units were staffed by a rotating schedule of the same ten SWL-certified radiological technicians. The treating urologists reported follow-up that included plain abdominal radiography to document stone-free rate ( no residual fragments) and the need for auxiliary procedures or re-treatment. An efficiency quotient (EQ) was calculated for each unit. Results: The overall stone-free rate for the STS-FIX, STS-MOB, and the STS-T was 59%, 62%, and 65%, respectively. The STS-FIX had the lowest stone-free rate for lower-pole stones (48%) and stones 21 mm to 30 mm (30%) compared with the STS-MOB (57% and 62%, respectively) and the STS-T ( 59% and 54%, respectively). However, the STS-FIX had a higher stone-free rate in the middle ureter ( 86%) than the STS-T (67%) and STS-MOB ( 65%). The STS-FIX required more post-SWL procedures overall (12%) than the STS-MOB ( 4%) and STS-T (5%). The re-treatment rates for the STS-FIX, STS-MOB, and STS-T were 7%, 6%, and 6%, respectively. The STS-T had the highest overall EQ ( 59) followed by the STS-MOB ( 56) and the STS-FIX ( 50). Conclusions: New configurations of the STS lithotripter have a significant positive impact on efficacy compared with the original fixed machine. Availability of real-time fluoroscopy with the STS-T may impact the higher EQ of this machine.