CLINICAL FACTORS ASSOCIATED WITH SPONTANEOUS PASSAGE OF URETER STONES IN CONSERVATIVE MANAGEMENT: 6 mm IN MAXIMAL STONE SIZE MEASURED BY ULTRASONOGRAPHY CAN BE A PREDICTIVE BORDER.

Abstract

(Purpose) To date there was no consensus regarding expectant size of stone and time to expulsion in the conservative treatment of ureter stones. The aim of this study was to find the clinical factors associated with stone passage by evaluating the outcome of ureter stones with expectant management in Japanese. (Materials and methods) A total of 679 ureter stone cases who visited our hospital with acute real colic and/or hematuria between 2009 and 2013, and who had decided to be treated by expectant management with or without medical expulsive therapy were enrolled in this study. All cases were examined size, location and presence of stone, and degree of hydronephrosis with ultrasonography. The examined data plus clinical data such as gender, age, side and body mass index were analyzed to find the factors related to spontaneous passage of ureter stones. Statistical analysis was performed to predict whether the factors were associated with the ureteral stone expulsion or not. (Results) Accumulated residual stone curve using Kaplan-Meier method showed time to 50%-expulsion as 15.7 days in cases with stone size no more than 6.0 mm and that as 21.8 days in those with greater than 6.0 mm, and time to 50%-expulsion as 28.8 days in cases with upper ureter stone whereas 15.6 days in those with middle or distal ureter stone. Analysis in groups with 1 mm-interval in stone size showed statistical significance only when compared 5-6 mm group with 6-7 mm group in size. Multivariate analysis showed stone size and location as statistically significant and independent factors to predict time to expulsion within 30 days. (Conclusion) Stone size and location was statistically reconfirmed to be associated with spontaneous passage in expectant management of ureter stones. This study statistically demonstrated the possibility that 6 mm in maximal stone size measured by ultrasonography can be a predictive border. 75% of ureter stones within 6 mm in maximal size measured by ultrasonography may expect to be expelled within 30 days.