The hydrodynamics of pyelorenal reflux. II. The effect of chronic obstructive changes on papillary shape.

Pyelotubular backflow has been shown to occur in primates at a physiologic, although somewhat higher than usual, ureteral pressure. Surgery to produce either partial ureteral obstruction or gross ureteral reflux caused a decrease in the pressure needed for pyelotubular backflow. The papilla is compliant and its shape is changed by these obstructive disorders. These findings help to explain the increased pyelonephritis associated with these abnormalities in patients.