Extracorporeal shock wave lithotripsy of lower calyx calculi: how much is treatment outcome influenced by the anatomy of the collecting system?

OBJECTIVES: Extracorporeal shock wave lithotripsy (ESWL) of lower calyx stones has been criticized because of the high incidence of residual fragments. Controversial results have been reported regarding the stone-free rate after ESWL depending on the influence of the collecting system anatomy on stone clearance. Therefore we evaluated our stone-free rate after ESWL of lower calyx stones and searched for correlations to various anatomic parameters of the collecting system.
METHODS: Ninety-six patients with isolated lower calyx stones treated exclusively with ESWL (Dornier HM3) were evaluated 3 mo postoperatively. The results were correlated with the following anatomic parameters of the collecting system as determined from the pretreatment intravenous urography: (1) lower infundibulum width, (2) lower infundibulum length, (3) infundibulopelvic angle, (4) volume of the collecting system. Follow-ups were performed 24 h after ESWL with an abdominal plain film and 3 mo postoperatively with a urography or abdominal plain X-ray together with renal ultrasound.
RESULTS: Three months postoperatively, 68% of all patients were stone free, including 69% of the patients with stones initially < or =1 cm, and 67% of the patients with stones >1 cm. Stone-free patients compared with patients having residual fragments had no significant differences in infundibulum width, infundibulum length, infundibulopelvic angle, or collecting system volume.
CONCLUSIONS: A stone-free rate 3 mo after ESWL of 68% overall justifies ESWL as a possible treatment option for lower calyx stones. Influence of the collecting system anatomy on disintegrate clearance from the lower calyx could not be demonstrated.