INVESTIGATION OF SELECTED PATIENTS WITH HYPERTENSION BY THE RAPID-SEQUENCE INTRAVENOUS UROGRAM

The rapid-sequence intravenous urogram (IVU) has tended to fall from favour for investigating hypertension because of its perceived imprecision for detecting renovascular disease. However, no study has examined the value of the IVU as a screening test in appropriately selected patients. We have analysed the diagnostic yield of the rapid-sequence IVU in hypertensive patients selected for features suggesting renal or renovascular disease in a retrospective review of case records from a hypertension clinic. The IVU was abnormal in 27% (95% Cl 21-32%) of 241 consecutive patients. The most common abnormalities were chronic pyelonephritis (6%); proven renovascular disease (5%); stone (4%); possible renovascular disease and simple cyst (each 3%); hydronephrosis (2%); and tumour and active tuberculosis (each 1%). The IVU led to intervention aiming to correct hypertension in 5% (95% Cl 2-8%) of patients, and revealed an abnormality needing intervention in its own right in 4% (95% Cl 2-6%). The IVU led to unnecessary invasive investigation in 3% of cases. Individual abnormalities could not be predicted from the clinical or laboratory features. The initial investigation in hypertensive patients with suspected renal or renovascular disease should be a general purpose test able to detect a wide range of abnormalities. The rapid-sequence IVU is the only single test capable of satisfying this requirement. In patients with features suggesting renovascular disease, a normal rapid-sequence IVU excludes renovascular disease with 93% probability, but is an imperfect screening test since it fails to diagnose about 20% of cases. Renal arteriography should be done despite a normal IVU when it is essential to exclude renovascular disease.