Estimation of renal pelvic volume in free urinary flow and in ureteral stasis. An experimental study in the rabbit.

At urography the radiopacity of the pelvis increases with the product of iodine concentration of the urine and its layer thickness. The layer thickness is proportional to the third root of the volume. Using this knowledge, we estimated the volume of the renal pelvis in rabbits and found it to be proportional to the diuresis up to a level of approximately 0.8 ml per min, after which a maximal dilatation seemed to be reached. By this means, the estimated density of the renal pelvis can be calculated. This model of evaluating urographic contrast agents is thought to be more appropriate than and complementary to the mere determination of urinary iodine concentration.