Pyelorenal backflow during retrograde pyelography in adult patients.

In a consecutive series of 103 retrograde pyelographies in adult patients suspect of disease in the upper urinary tract, the overall incidence of pyelorenal backflow was 18%. Pyelosinous backflow--seen in 11%--was much more frequent in kidneys with obstructed ureter (20%) than in non-obstructed kidneys (3%). Intrarenal backflow, so far regarded as a rare form of backflow, was almost as frequent as pyelosinous backflow. It occurred in 13% of kidneys with obstructed ureter as opposed to 7% in non-obstructed kidneys. Intrarenal backflow mostly involved only a section of the kidney, in 75% of cases in the upper pole. It occurred both in diseased and in apparently normal kidneys. Pyelosinous and intrarenal backflow in the same kidney was seen in 2% of cases.