Duplex scan sonography of renal artery stenosis.

Renal artery stenosis is the most common cause of potentially remediable secondary hypertension. The most common causes include atherosclerosis and fibromuscular dysplasia. Particularly the atherosclerotic form is a progressive disease that may lead to gradual and silent loss of renal functional tissue. Thus, early diagnosis of renal artery stenosis is an important clinical objective since interventional therapy may improve or cure hypertension and preserve renal function. Screening for renal artery stenosis is indicated in the suspicion of renovascular hypertension or ischemic nephropathy in order to identify patients in which an endoluminal or a surgical revascularization is advisable. In the recent years many noninvasive tests have been proposed and evaluated in the clinical practice, in alternative to arteriography. These include nuclear scan, color Doppler sonography, CT angiography and MR angiography. Sonography is usually the first diagnostic modality for the non invasive evaluation of renal vascular disease with 95% sensitivity and 90% specificity when performed in dedicated laboratories. Despite sonography is highly affected by operator dependence, and it takes a lot of time to train good operators, actually is the best screening test because it is not expensive, non invasive and accurate. When a discrepancy exists between the clinical data and the results of US, other tests are mandatory.