Simplified method using kidney/ureter/bladder x-ray to determine the appropriate length of ureteral stents

Purpose: To investigate a method to determine the appropriate length of ureteral stents, given that the stent length may lead to exacerbation of urinary symptoms if the stent crosses the bladder midline. Materials and Methods: We retrospectively reviewed the position of the distal curl of the ureteral stent using kidney/ureter/bladder (KUB) radiographs after ureteroscopic lithotripsy in 165 patients who underwent placement of 24- or 26-cm ureteral stents. According to the KUB findings, we categorized the position of the distal curl of the ureteral stent into two groups. In Group 1, the stents did not cross the midline (appropriate length); in Group 2, the stents crossed the midline (inappropriate length). We assessed several patient parameters (sex, height, body mass index, and stone side) and the index of ureteral length using KUB radiographs ("C-P") and computed tomography (CT, "PV"). Multivariate analysis was performed to identify the most significant factors affecting the position of ureteral stents. We also calculated the cutoff points of the receiver operating characteristic (ROC) curve of C-P and P-V for the position of ureteral stents. Results: The multivariate analysis showed that C-P was the most significant factor affecting the position of ureteral stents (p < 0.001) in patients with 24- and 26-cm ureteral stents. Comparison of the ROC curves of C-P and P-V showed that C-P was superior to P-V (p < 0.01) in patients with 24- and 26-cm stents. Conclusion: The use of KUB radiographs was effective and simple in determining the appropriate length of ureteral stents.