Infundibulopelvic anatomy and clearance of inferior caliceal calculi with shock wave lithotripsy

Purpose: We evaluate the significance of inferior caliceal radiographic ana tomy and determine its influence on successful fragmentation and clearance of inferior caliceal calculi with extracorporeal shock wave lithotripsy (ES WL*). Materials and Methods: Between November 1996 and February 1998, 88 patients and 90 renal units with single or multiple inferior caliceal calculi of al l sizes and composition were treated with ESWL. The size, number and area o f calculi, length and width of the stone bearing inferior calix and infundi bulopelvic angle were determined on pretreatment excretory urography. The i nfundibulopelvic angle was measured by 2 methods using the angle between th e inferior caliceal infundibular and ureteral axes (angle 1), and between t he infundibular and ureteropelvic axes (angle 2). Cases with residual fragm ents not clearing within 6 months of satisfactory fragmentation after litho tripsy were considered failures. Results: Overall stone clearance at 6 months was achieved in about 72% of t he renal units. Infundibular length was 30 mm. or less in 77% of successful cases and in 64% of failures. Similarly, the smallest infundibular width o f 5 mm. or more was found in 75% of successful cases compared to 41% of fai lures. Angle 1 of 35 degrees or more was observed in 73% of cases with comp ared to 18% without clearance. Angle 2 of 45 degrees or more was seen in 71 % of successful cases compared to 9% of failures. The chances of a patient becoming stone-free with all favorable criteria of infundibular length 30 m m. or less, infundibular width 5 mm, or greater and infundibular ureteropel vic angle 45 degrees or greater was 100% (23 patients). Conclusions: Radiographic features of a stone bearing inferior calix and it s relation to the renal pelvis can be easily measured on standard excretory urography. An infundibular width of 5 mm. or more and infundibulopelvic an gle 1 of 35 degrees or more or angle 2 of 45 degrees or more were statistic ally significant factors of radiographic anatomy in stone clearance followi ng ESWL. Inferior caliceal length was not statistically significant, althou gh length of 30 mm. or less appeared to be more favorable for stone clearan ce. The ideal treatment of inferior caliceal calculi in patients with all 3 favorable criteria is ESWL.