[Pyelo-interstitial reflux]

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.

Pyelorenal backflow during retrograde pyelography after renal transplantation

Retrograde pyelography in 140 transplanted kidneys within 3 days of the operation showed a high frequency (29%) of pyelorenal backflow. Pyelotubular backflow, ordinarily a rare form of backflow, was seen in one-third of the patients whose transplants were removed within 60 days because of rejection, but in only 4% of the patients with surviving grafts. Pyelosinus backflow was found in 61% of the patients with signs of urinary obstruction, but in only 9% of the other patients. No relationship was found between pyelosinus backflow and graft rejection, or between pyelotubular backflow and urinary obstruction. Pyelotubular backflow may be an early radiographic sign of impending and serious rejection.