Stone Free Rate of SWL in Renal Calyceal Stone according to Its Location

Yoon, Cheol Yong; Kim, Dong Sun; Lee, Jeong Gu

Abstract

PURPOSE: Intrarenal location of calculus significantly affects efficacy of SWL. In lower calyceal stone, its antigravitic location has been known to decrease success rate of SWL. In this study, renal calyceal stone is categorized according to its location and especially lower calyceal stone is further divided either with infundibulo-pelvic angle (IPA) greater than 90degreesor that with less than 90degrees. Difference of the treatment results were compared according to the location of stones.
MATERIALS AND METHODS
142 stones(upper calyx: 52, mid calyx: 11, lower calyx: 79) of 117 patients which had been treated by SWL since 1995 were retrospectively studied. The SWL machine used for treatment was EDAP-LT 01 Plus(piezoelectric mechanism with 3.5 MHz ultrasonic imaging system). Complete stone delivery was defined as state with no residual stone on KUB film.
RESULTS
The mean stone size was 0.97+/-0.3cm and mean number of treatment session was 5.0+/-3.2. The complete stone delivery rate was 83%. There was no significant difference in number of session according to stone location(upper calyx: 4.4+/-1.9, mid calyx: 3.18+/-1.5, lower calyx: 4.8+/-2.4, p>0.05). The stone sizes of each calyx were 1.1+/-0.33cm, 0.8+/-1.5cm and 0.91+/-0.24 cm respectively. There were no siginificant differences in stone size among calyceal location(p>0.05). The complete stone delivery rate of each calyx were 88.5%(46/52), 90.9%(10/11), 74.7%(59/79) respectivey(p>0.05). Of the 79 lower calyceal stones, of which IPA was greater than 90degreesin 27 stones and less than 90degrees in 52 stones. There was no siginificant difference in size between two groups(0.86+/-0.16cm vs 0.9+/-0.25cm, p>0.05). The stone with greater infundibulo-pelvic angle had more session than that with lesser infundibulo-pelvic angle(4.9+/-2.2 vs 4.3+/-3.3, p=0.039). There was significant difference in complete stone delivery rate according to infundibulo-pelvic angle(96.3% - 26/27 vs 63.4% - 33/52, p=0.034). Also stone with less infundibulo-pelvic angle had inferior stone delivery rate compared with that of upper and mid calyceal stone.
CONCLUSIONS
The lower calyceal stones with infundibulo-pelvic angle lesser than 90degreeshad significantly lower stone delivery rate compared with those with greater infundibulo-pelvic angle and upper and mid calyceal stone. In case of lower calyceal stone with infundibulo-pelvic angle less than 90degrees, other treatment such as PNL, pyelolithotomy must be considered as primary treatment modality.