Role of duplex ultrasonography in screening for significant renal artery disease.

Duplex ultrasound examination of the renal arteries is an excellent screening test for the presence of significant RAS. It is important to recognize that each technician and physician must validate his or her results against the gold standard-arteriography. Currently we are able to differentiate less than 60% stenosis from greater than 60% stenosis and to detect totally occluded renal arteries. In the near future we hope to be able to further subdivide the greater than 60% group in a manner similar to what has been done with carotid artery duplex scanning. The noninvasive nature of duplex scanning is ideal for the patient with an elevated serum creatinine in whom the physician wants to determine, with a high degree of likelihood, whether significant renal artery disease is contributing to the azotemia. Accessory renal arteries are a problem in that in the best series reported, the sensitivity was only 67% but the specificity was 100%. Identification of accessory renal arteries will improve as the equipment improves and as the ultrasonographer becomes more experienced. Duplex scanning is useful in following patients after PTRA, renal artery stents, or bypass surgery to document the initial patency of the vessel and to follow the long-term patency of these vessels. Duplex scanning will also be a useful way to follow the natural history of renal artery disease.