[Characteristics of ureteral stone position and dilatation of ureter in patients before treated with endourologic lithotripsy].

OBJECTIVE: To investigate the position and the size of ureteral stone in patients before treated with ureteroscopic lithotripsy or percutaneous nephrolithotomy (PCNL), as well as the dilatation of ureter caused by stone, which may be helpful for better understanding of pathogenesis of ureteral stone and improvement of the diagnosis and treatment in clinic.

METHODS: A total of 129 cases with ureteral stone for endourologic lithotripsy in Peking University People's Hospital from Aug. 2016 to Mar. 2017 were included for the retrospective review. The CT data of the ureteral stones and the ureteral dilatation were collected, including the position of stone, the transverse and longitudinal diameter of stone, and the transverse diameter of dilated upper ureter and ureteropelvic junction (UPJ). The distribution of ureteral stones and dilatation in different parts of ureter were compared and analyzed.

RESULTS: All of the 129 cases of ureteral stone, stones were located at UPJ in 9 cases (7.0%), proximal ureter in 75 (58.0%), ureter crossing external iliac vessel (UEIV) in 6 (4.7%), distal ureter in 26 (20.2%), and ureterovesical junction (UVJ) in 13 (10.1%). The mean transverse diameter of proximal ureteral stones was greater than that of distal ureteral stones [(8.47±2.36) mm vs. (6.74±1.99) mm, P<0.001], as the same as the mean longitudinal diameter [(11.00±4.41) mm vs. (7.50±4.28) mm, P<0.001]. In 114 cases of dilated ureter for stone, the UPJ had a greater transverse diameter compared with the upper ureter [(14.39±6.09) mm vs. (11.45±3.85) mm, P<0.001].

CONCLUSION: The most common location of stone is the proximal ureter in patients for endourologic lithotripsy, as the location in UEIV is rare. Both transverse and longitudinal diameters of stone in proximal ureter are greater than those in distal ureter. For dilated ureter, it is more severe in UPJ than in upper ureter. Traditionally, it is accepted that the stones lodge at 3 sites of natural narrowing in ureter, which may be questioned.