Measuring individual ureteral length using computed tomography urography to determine the appropriate lengths of ureteral stents

Purpose: The purpose of the study was to describe and validate a method for calculating ureteral length using computed tomography (CT) images acquired before ureteral stent placement and to evaluate the appropriateness of fit based on this calculation. Materials and Methods: We analyzed 57 patients who underwent computed tomography urography (CTU). The axial ureteral length (AUL) and coronal ureteral length (CUL) were derived from measurements made on the CTU images, and the length of each patient-specific ureteral stent was chosen based on the calculated ureteral length. Results: Overall, 105 ureters were measured: 54 (51.4%) right side and 51 (48.6%) left side ureters. The mean CUL and AUL of right ureters were 22.5 ± 2.3 cm and 22.5 ± 2.3 cm, respectively, whereas the mean CUL and AUL of left ureters were 23.6 ± 2.2 cm and 23.4 ± 2.1 cm, respectively. Pearson correlation analysis showed that body height was significantly correlated with ureteric length (right CUL and patient height: r =0.441, P = 0.001; right AUL and patient height: R = 0.445, P = 0.001; left CUL: R = 0.341, P = 0.029; left AUL: R = 0.339, P = 0.015). Thirteen of 57 patients underwent ureteral stent insertion; none experienced stent migration (upward or downward) before the removal of the ureteral stent. Comparison of proposed stent size with actual stent size in the 13 patients shows the percentage of size appropriateness (as defined by concordance between proposed and actual stent length) to be 76.9% (10/13). Conclusion: The patient's height was found to correlate significantly with CT-derived measurements of ureteral length. Accordingly, the choice of ureteral stent length can be reliably decided from CT measurements.