Ultrasound as a first line screening tool for the detection of renal artery stenosis: a comprehensive review.

Renal artery stenosis (RAS) is the most common underlying medical condition in secondary hypertension among adults, representing about 5% of all cases of hypertension. Early diagnosis of RAS is an important clinical objective since interventional therapy may improve or cure hypertension and preserve renal function. Contrast angiography is the currently reference standard for the diagnosis of RAS; however, its invasive nature renders it unsuitable for screening purposes. Among screening tests used for the detection of RAS (computed tomography angiography, magnetic resonance angiography, radionuclide scanning), multiple studies have shown that color Doppler ultrasound (CDUS), although highly operator-dependent, can be an effective tool in the diagnosis of RAS. CDUS imaging is a simple, safe (noninvasive) and widely available technique; in addition, the procedure is painless and well tolerated by patients. In this concrete review we will underline the established color Doppler ultrasound criteria used for the detection of RAS, highlight their limitations and see how their combination may improve the diagnostic accuracy of this method.