Color-coded duplex sonography in the diagnosis of renal artery stenosis—A 3-year experience in a large community hospital

Abstract

From October 1991 to May 1995 we examined 1018 patients admitted for suspected renal artery stenoses. Of these, 229 consecutive patients (143 males and 86 females) were subjected to angiography. The mean age was 59 years (range 9–79 years). We used an Acuson 128 XP 10 duplex-unit with a 2/2.5-MHz sector probe. Color-coded tracings, pulsed-mode and continuous-mode Doppler readings were taken from the intra- and extrarenal arteries in order to define the velocity of the blood, to find spectral disturbances, and to calculate the resistive index (Pourcelot index) from these readings. In 85% of the patients a complete screening of the vessels was possible. The diagnosis of significant renal artery stenosis, i.e., a 60% reduction of diameter, was made when the maximal systolic velocity (V_max) was above 1.60 m/second. In patients with V_max between 1.20 and 1.60 m/second the diagnosis of a significant stenosis was made if spectral disturbances were present and a >40% reduced velocity was found elsewhere in the same main renal artery. With these criteria, color-coded duplex sonography (CCDS) in our 229 patients had a sensitivity and specificity of 86% and 96%, respectively. With an 83% prevalence of significant stenoses, the positive predictive value was 96%, the negative predictive value 83%. Forty-eight of the 67 accessory arteries to the kidney could be demonstrated by CCDS. We conclude that CCDS is an excellent screening tool to detect renal artery stenoses in the main renal arteries. Problems arise from stenosed accessory small vessels with hilar or polar destination which can be overlooked with CCDS. CCDS is indispensable for longitudinal follow-up of known renal artery stenoses and for control after angioplasty or operation for renovascular disease.