Microradiographic demonstration of pyelolymphatic backflow in the porcine kidney.

Pyelolymphatic backflow occurs when intrapelvic pressure rises acutely. Although peripelvic and hilar lymphatics have occasionally been demonstrated during intravenous urography and retrograde pyelography, the patterns of intrarenal microlymphatic filling have not previously been studied radiographically in multipapillary kidneys. Microradiography was performed after retrograde ureteral injections of barium sulfate suspension in recently excised pig kidneys. Contrast filled the ducts of Bellini and extended in a retrograde fashion as far as the distal convoluted tubules. Intrarenal cortical and corticomedullary microlymphatics, as well as veins, filled following forniceal rupture and interstitial extravasation. These anatomic studies suggest that the renal lymphatics may function as an alternate pathway of drainage of an acutely obstructed kidney.