We determined whether the gravity effect of radiographic anatomic features on the preoperative urography (IVP) are enough to predict fragments clearance after shock wave lithotripsy (SWL). A Total of 282 patients with mean age 45.8 ± 13.2 years (189 male, 93 female), who underwent SWL due to renal calculi between October 2005 and August 2009 were enrolled. The mean calculi load was 155.72 ± 127.66 mm². The patients were stratified into three groups: patients with pelvis calculi (group 1); patients with upper or middle pole calculi (group 2) and patients with lower pole calculi (group 3). Three angles on the pretreatment IVP were measured: the inner angle between the axis of the lower pole infundibular and ureteropelvic axis (angle I); the inner angle between the lower pole infundibular axis and main axis of pelvis-ureteropelvic (UP) junction point (angle II) and the inner angle between the lower pole infundibular axis and perpendicular line (angle III). Multivariate analysis was used to define the significant predictors of stone clearance. The overall success rate was 85.81%. All angles, sessions number, shock waves number and stone burden were significant predictors of success in patients in group 1. However, in group 2 only angle II and in group 3 angles I and II had significant effect on stone clearance. Radiographic anatomic features have significant role in determining the stone-free rate following satisfactory fragmentation of renal stones with SWL. The measurement of infundibulopelvic angle in different manner helps to predict the stone-free status in patients with renal calculi located not only in lower pole, but also in renal pelvis and upper or middle pole. Gravity effect is not enough to justify the significant influence of the radiographic anatomic features on the stone clearance and fragments retention after SWL.
Objective: To assess the effect of the gravity-related
radiographic features on the success rate of extracorporeal shock wave
lithotripsy (SWL) in renal stones.
Materials and methods: A total of 79 patients (mean
age 47.34±12.9 year) who underwent SWL due to renal pelvis stones (mean
area 162.58±130.31 mm²) between 2005 and 2008 were enrolled. Three
angles on the pretreatment excretory urography were measured; the inner
angle between the axis of the lower pole infundibular and ureteropelvic
axis (angle 1), lower pole infundibular axis and main axis of
pelvis-ureteropelvic junction point (angle 2), and lower pole
infundibular axis and perpendicular line (angle 3). Age, number of
session, stone burden, numbers of shock waves, and presence of
hydronephrosis were defined for all patients. The significant predictors
of stone-free rate after the application of SWL was defined.
Results: The success rate was 53.2%. All angles,
number of sessions, stones burden, and number of shock waves were
significant predictors of stone free rate. However, age, sex and the
presence of hydronephrosis did not show similar effects.
Conclusions: Gravity-related factors have significant
role on the stone-free rate in patients treated with SWL for renal
pelvis stones. These radiographic parameters may be used to determine
the patients who will benefit from SWL.