Results
Of the 147 patients evaluated, 77 (52.4%) had right ureteral stones and
70 (47.6%) had left ureteral stones. The mean patient age was 42.4 ±
12.8 years (Table 1). The median transverse stone size was 7.5 mm (min
2.8 - max 15) and the median UWT was 4.2 mm (1 - 8.7). The median stone
density was 822 HU (275 - 1628), and the median stone volume was 277.4
mm³ (36 - 2134.8). The mean SSD was 124.8 ± 23.6 mm. Based on the data
collected over a three-month follow-up period after SWL, 136 (92.5%) of
the patients were identified as stone-free while treatment failure was
seen in 11 (7.5%). In the presence of multiple stones, the stone-free
rate was 50% (Table 2).
When stone-related parameters were analyzed statistically, UWT (p
< 0.001), presence of multiple stones (p < 0.001),
and increased diameter of the ureter in the proximal of the stone (p =
0.050) were found to increase the treatment failure rate. Transverse
stone size (p = 0.883), stone length (p = 0.365), stone volume (p =
0.594), HU (p = 0.819), side of the stone (p = 0.160), and SSD (p =
0.803) did not affect stone-free status (Table 2). In the receiver
operating characteristic (ROC) curve analysis, the optimal threshold
value for UWT and the diameter of the ureter in the proximal of the
stone were determined as 5.25 mm and 11.95 mm, respectively. The
treatment was successful in all 124 patients (100%) with a UWT of
<5.25 mm. Among the patients who had a UWT of ≥5.25 mm, the
treatment was successful in 12 (52.1%) and failed in 11 (47.9%). The
sensitivity of this threshold (UWT < 5.25 mm) for SWL
treatment success was 100%, specificity was 91.2%, positive predictive
value was 47.8%, and negative predictive value was 100%.
When the patient-related factors were analyzed, although treatment
failure increased in patients with comorbidities according to the
univariate analysis (p = 0.030), no relationship was found in the
multivariate analysis (p = 0.117). Age (p = 0.083), gender (p = 0.514),
and history of operation (p = 0.579) (Table 1) did not affect the
failure rate.
When the treatment modalities were examined, the median number of
sessions was 2 (1 - 7), the median number of shockwaves per session was
3000 (300 – 3800) and the mean amount of energy applied per session was
75.7 ± 22.7 joules. Treatment success increased as the number of
sessions decreased (p = 0.001). However, no relation was found in the
multivariate analysis (p = 0.535). No statistically significant
correlation was found between the failure rate and the number of median
shockwaves (p = 0.094) or the mean shockwave power applied (p = 0.054)
(Table 2). Treatment success decreased in those who had undergone
ancillary procedures (p = 0.048) before SWL, but no significant
relationship was found in the multivariate analysis (p = 0.989). The
multivariate analysis revealed UWT (p = 0.002) and multiple stone
presence (p = 0.027) as independent predictive factors of stone-free
status (Table 3).