Studies on the influence of the flow field in the pelvi-calyceal system (PCS) on the formation of urinary calculi.

Following a morphological analysis of pelvi-calyceal systems (PCS) of healthy persons and urolithiasis patients, rheological studies from glass and rubber PCS-models are presented. In the PCS of urolithiasis patients morphological and geometrical differences were found, causing a flow pattern which favours calculus formation. In urolithiasis, the PCS is characterized by cavities with significantly reduced flow rates and stagnation of urine. The formation of urinary calculi is often promoted by a hypomotility of the muscles of the PCS, common in urolithiasis patients. Possible therapeutic and diagnostic consequences are discussed.