Evaluation of the urea washout pyelogram and urography in the assessment of renovascular hypertension.

The urea washout (UWT) modification of the intravenous pyelogram was used to study 146 hypertensive patients in order to detect the presence of significant renovascular abnormalities. A positive result was obtained in 55 patients and direct confirmation of main renal artery stenoses by selective renal arteriography was obtained in 26. Bilateral abnormalities were confirmed in seven of the 26 patients. No false-negative results were encountered. The usefulness of this test as a comprehensive screening test is outlined. It demonstrated a high degree of accuracy in the diagnosis of significant unilateral or bilateral main renal artery stenosis in addition to the detection of diffuse intrarenal arteriolar disease. It was of value in the postoperative assessment of operative repair of main renal artery defects. The urea washout test embodies both an anatomical and a physiological approach in the roentgen diagnosis of curable renovascular hypertension. The altered physiology resulting from significant main renal artery stenosis makes possible the use of the urea washout intravenous pyelogram. The value of other forms of intravenous pyelography is described.