[Topographic anatomy of the caliceal stem: the colonic risk]

Body-section roentgenograms were taken of seventy five patients examined for non-urological complaints. These were studied and the axes of the ventral and dorsal calices were measure. The axis of the ventral calix passes through the left or right colon. The axis of the dorsal calix follows the avascular line and passes to the lateral border of the paravertebral muscles, avoiding the left and right colon. These anatomical data confirm that the dorsal calix is the route of choice in the percutaneous approach to the kidney.