In Situ Extracorporeal Shock Wave Lithotripsy for Ureteral Calculi: Investigation of the Factors Influencing on Stone Fragmentation and the Appropriate Session for Changing Treatment Modality

Kim, Hyeon Hoe; Lee, Jin Haeng; Park, Eun Chan; Byeon, Seok Soo; Oh, Seung Joon; Paick, Jai Seung; Choi, Hwang; Kim, Si Whang

Abstract

To determine the factors influencing on stone fragmentation and the appropriate session for changing treatment modality of ureteral calculi refractory to in situ ESWL, we analyzed 369 patients with ureteral calculi primarily treated by second-generation lithotripter, Siemens Lithostar from March,1989 to December, 1993. The results obtained were as follows: 1.Three hundred and forty two(92.7%) of the total 369 patients were ultimately free of stones by repetitive performance of in situ ESWL ranging from the first session to the tenth session. 2. The cumulative stone-free rates of the first, second and third session were 64%, 81% and 88%, respectively, and the increment of cumulative stone-free rate thereafter with further repeated in situ ESWL was minimal(p<0.01). 3. According to the location of stone, the cumulative stone-free rate at third session was 89%, 87% and 86% in proximal, middle and lower ureter stones, respectively(p>0.05). 4. According to the size of stone, the cumulative stone-free rate at third session was 100%, 90%, 87%, 70%, 67%, 50% in stones less than 5 mm, 6-10 mm, 11-15 mm, 16-20 mm, 21-25 mm and above 25 mm, respectively(p<0.001). 5. According to the radio-opacity of stone, the cumulative stone-free rate at third session was 96% in stones with minimal opacity, 94% with moderate opacity and 70% in highly opaque stones(p<0.001). 6. According to the degree of ureteral obstruction due to stone, the cumulative stone-free rate at third session was l00% without ureteral obstruction, 80% with mild, 57% with moderate, 67% with severe ureteral obstruction, and it was 50% in patients with non-visualization of the kidney(p<0.05). From these observations, it could be concluded that the factors influencing on stone fragmentation were the size of calculi, radio-opacity and the degree of ureteral obstruction, whereas the location of the ureteral calculi did not influence on the cumulative success rate of repetitive in situ ESWL. Also, it is preferable to restrict the repetitive sessions of in situ ESWL within third session in patients with the ureteral calculi refractory to in situ ESWL, and early change of surgery would be retreatment modality either to ureteroscopic manipulation or to open commended if there are risk factors listed above.