Risk factors for steinstrasse formation after extracorporeal shock wave lithotripsy for renal pelvic stones

This study aimed to identify predictive factors for the formation of steinstrasse following extracorporeal shock wave lithotripsy (SWL) in patients with medium-sized (10-20 mm) renal pelvic stones.

This retrospective cohort study, data of 718 patients who underwent SWL for urinary tract stones were analyzed and single, unilateral, radio-opaque renal pelvic stones were included in the study. Patient age, sex, stone side, shape (round/non-round), size, surface area (SA), and presence of hydronephrosis were recorded. Patients were divided into two groups depending on the presence of steinstrasse: Group 1 (with steinstrasse) and Group 2 (without). Demographic, clinical, and radiological parameters were compared between the groups.

The mean age of the patients was 50.8 ± 11.2 years. The average number of SWL sessions was 2 (range 1-4). Group 1 included 12 patients (23.1%), while Group 2 comprised 40 patients (76.9%). The mean SA in Group 1 was significantly higher than in Group 2 (145.43 vs. 111.69 mm²; p = 0.044). Round stones were more frequently observed in Group 1, whereas non-round stones predominated in Group 2 (83.3% vs. 62.5%, respectively; p = 0.008). The overall SWL success rate was determined as 76.9%. Logistic regression analysis revealed that round stones increased the risk of steinstrasse by 8.333 times (OR = 8.333, 95% CI = 1.604-43.288, p = 0.012).

SA was higher in patients who developed steinstrasse. Since the likelihood of steinstrasse formation is elevated in medium-sized round renal pelvic stones, pre-stenting may be appropriate.