Extracorporeal shock wave lithotripsy for large renal calculi: the role of ureteral stents. A randomized trial.

Ureteral stents reduce complications after extracorporeal shock wave lithotripsy (ESWL*) and contribute to successful stone passage. However, some reports note complications that are attributed to indwelling ureteral stents. We randomized 64 patients with large renal calculi (stone burden more than 200 mm.2) for in situ treatment or treatment with a prophylactically inserted stent. We used a 6Ch round stent with single-coiled ends or a triangular shaped stent with double-coiled ends. Patients were treated with a Siemens Lithostar lithotriptor. After 3 months we evaluated the results of treatment and post-ESWL morbidity. Of the in situ group (23 patients) treatment complications consisted of fever in 3, pyelonephritis in 1 and steinstrasse in 3. After 3 months 8 patients (35%) were free of stones. Of the stented population (41 patients) treatment complications consisted of fever in 7, pyelonephritis in 1, steinstrasse in 6 and bladder discomfort in almost half of the patients. Stent calcification and stent migration were also seen in 7 and 10 patients, respectively. Calcified stents had been in situ longer than noncalcified stents. The round stents migrated and calcified more often than the more rigid triangular stents. After 3 months 18 of the stented patients were stone-free (44%). We conclude that ureteral stents do not reduce post-ESWL complications. They are clearly associated with morbidity and do not improve stone passage markedly. Therefore, patients with a stone burden of more than 200 mm.2 should be treated in situ without auxiliary stenting.