Introduction
The European Association Urology (EAU) guidelines recommend extracorporeal shock wave lithotripsy (SWL) or ureterorenoscopy (URS) as the first choice of treatment in proximal ureteral stones of less than 10 mm while for those larger than 10 mm, the first option is URS and the second option is SWL treatment. [1] SWL is the most minimally invasive and anesthesia-free option in stone treatment. Most patients can be treated in outpatient settings. Many factors affect the results of SWL treatment. Proper patient selection increases the success rate, and stone size is inversely proportional to treatment success. [2] In addition, it has been stated that the ability of stone targeting affects the success rate. [3]
In the disease process, if the impacted stones remain in the same location for a long time, the contact of the stone with the ureteral mucosa can cause local inflammation and edema [4,5], leading to an increase in the ureteral wall thickness (UWT). In a previous study, SWL success was reported to decrease as the UWT increased in patients with impacted proximal ureter stones. In that study, an impacted stone was defined as a ureteral stone remaining in the same position (and/or presence of symptoms) for at least one month, accompanied by the failure of visualization of the distal segment of the ureter beneath the segment of the stone on intravenous urography or computed tomography (CT) urography. [6] However, there is insufficient data in the literature regarding the definition of impacted ureteral stones. Most definitions provided are subjective and aim to improve the success of SWL treatment. When the literature studies are analyzed, a discrepancy is also observed in relation to the predictive factors affecting success in the SWL treatment of proximal ureteral stones. [7,8] Therefore, it is still difficult to choose the appropriate treatment for proximal ureteral stones.
Innovations in SWL technology have increased the success rate and made it a favorable choice of treatment. In this study, we aimed to determine the predictors that might affect the stone-free status. For this purpose, we investigated the effect of UWT and other variables on the treatment results in patients who received SWL as the primary treatment of ureteral stones above the iliac crest level.