Pitfalls and Sources of Error of Color Duplex Sonography in Screening for Renovascular Hypertension

Background and Aims: To discuss sources of error and pitfalls of color duplex sonography (CDUS) in screening for renovascular hypertension (RVH). Methods: We retrospectively reviewed 47 patients with positive CDUS in patients with suspected RVH from May 1, 2007 to February 28, 2009. Manifestations of RVH on CDUS were analyzed. The results of main renal artery stenosis on CDUS were confirmed with that of magnetic resonance angiography (MRA), computed tomographic angiography (CTA), or digital subtraction angiography (DSA). Pitfalls and sources of error of CDUS in screening for RVH were identified. RVH was classified into three groups: 1) main renal artery stenosis (RAS); 2) intrarenal artery stenosis; and 3) intrarenal arteriovenous fistula (AVF). Results: Two cases of false positive and two cases of false negative main RAS on CDUS were corrected by MRA or DSA. Three cases with intrarenal artery stenosis and four cases with intrarenal AVF were not visualized at the initial CDUS but detected on repeat studies. Peak systolic velocity > 2 m/s at the stenotic artery was the most sensitive parameter for detecting RAS in either main renal artery or intrarenal artery. Acceleration time > 0.07 m/s in the intrarenal artery was seen in only 10 cases (10 /20, 50%) with hemodynamically significant main RAS (>60% arterial lumen reduction). Conclusions: Some pitfalls and sources of error of CDUS can be corrected and minimized with proper scanning and interpretation. Intrarenal RAS and AVF should be investigated with optimized Doppler settings. CDUS, with its advantages outweighing its limitations, should be considered a first line study in screening for RVH by experienced ultrasound professionals.