Extracorporeal shockwave lithotripsy for stones in abnormal urinary tracts: analysis of results and comparison with normal urinary tracts.

PURPOSE

We reviewed our experience with SWL for stones in abnormal urinary tracts and compared the results with those in normal urinary tracts.

PATIENTS AND METHODS

The study group was composed of 2566 renal units (RU) treated on the Siemens Lithostar lithotripter at our SWL unit whose treatment and follow-up at 10 to 12 weeks were completed. Sixty-eight RUs (2.7%) belonged to 52 patients who had congenital upper urinary tract abnormalities. Logistic regression analysis was performed to analyze the impact of age, stone size, location, and the type of abnormality on the outcome of the SWL in the abnormal RU. The student t-, chi-square, and Fisher's exact tests were used for the comparison of stone load, number of treatment sessions, catheter placement, and success rates of the patients with normal and abnormal RU. Results of long-term follow-up for available patients (38 RU; 56%) were also evaluated.

RESULTS

Age, stone load, stone location, and the type of abnormality did not have a statistically significant impact on the outcome of SWL for abnormal RU. The average stone load was 2.1 +/- 2.8 cm2 in the abnormal and 1.4 +/- 1.3 cm2 in the normal RU. Thus, the stone load was significantly higher in the abnormal RU (P < 0.05). In the abnormal group, 56% of the RU became stone free, 37% had nonobstructive and noninfectious clinically insignificant residual fragments < or = 4 mm (CIRF), and SWL failed in 7%. In the normal group, 78% of the RU became stone-free, 18.5% had CIRF, and SWL failed in 4%. There was no significant difference in the success rates in the groups if success was defined as stone free and CIRF together (P > 0.05). However, there was significant a difference when stone-free, CIRF, and failure rates were evaluated separately (P < 0.05). Recurrence, regrowth, and retreatment rates in abnormal RU were 50%, 37%, and 34%, respectively.

CONCLUSIONS

Although the fragmentation rates were similar, clearance of the fragments was hampered in abnormal urinary tracts. Thus, especially for large stones, other endourologic treatment options should be considered. High recurrence and regrowth rates warrant careful monitoring and consideration for medical treatment during follow-up.