Continuous infusion urography in unilateral hydronephrosis.

In cases of unilateral hydronephrosis the urine concentration of contrast medium, for example diatrizoate, depends on the remaining renal function, the rate of turnover in the obstructed renal pelvis and the function of the contralateral kidney. Contrast medium for a single injection or a short infusion time is rapidly excreted by the normal contraleteral kidney, without allowing high enough plasma levels long enough for sufficient urine concentrations in the hydronephrotic kidney. This excretion rate can be compensated for by continuous infusion urography for several hours with large doses of contrast medium (up to 1,250 ml. 30 per cent diatrizoate). This method was theoretically computerized, tested in animals experiments and clinically used in 11 patients. It can improve the diagnostic possibilites of excretory urography, especially in cases of unilateral obstruction, and can minimize the need for retrograde pyelography with its known complications.