Limitations of extracorporeal shockwave lithotripsy for lower caliceal stones: anatomic insight.

In addition to gravity-dependent position, we suppose that other particular anatomic features may be important in the retention of stone debris in lower calices after extracorporeal shockwave lithotripsy (SWL). We analyzed the inferior-pole collecting system anatomy in 146 three-dimensional polyester resin corrosion endocasts of the pelviocaliceal system. In 74% of the cases, there was an angle of greater than 90 degrees formed between the lower infundibulum and the renal pelvis, and in 26%, the angle was 90 degrees or less. In 60%, there was a lower infundibulum 4 mm or larger in diameter. The inferior pole was drained by multiple calices disposed in two rows in 57% of the cases and by one midline caliceal infundibulum in 43%. We believe that the physician must appreciate these anatomic features when considering SWL to treat calculi located in lower calices.