Accuracy of Doppler ultrasound in diagnosing anatomic stenosis of hemodialysis arteriovenous access as compared with fistulography

A variety of techniques (physical examination, venous pump pressure, percent urea recirculation, Crit Line, Transonic Flow, and others) are helpful in detecting vascular access dysfunction with subsequent referral to fistulography for confirmation of stenosis and possible angioplasty. Although these techniques are adequate, it is not uncommon that the results in some patients may be borderline or equivocal. In these cases, Doppler ultrasound may play a role to confirm the presence or absence of significant stenosis before subjecting the patient to the more expensive and invasive fistulography. For Doppler ultrasound to play such a role, it must have a high degree of accuracy in diagnosing anatomic stenosis. In previous studies, percent stenosis by Doppler ultrasound as compared with percent stenosis by fistulography was examined only when stenosis was suspected, therefore not allowing the determination of Doppler ultrasound specificity in diagnosing negative stenosis when fistulography was negative. In this study, we evaluated 38 hemodialysis patients with Doppler ultrasound followed by fistulography, without regard to suspicion of stenosis (to access both the sensitivity and specificity of Doppler ultrasound). Nineteen patients (50%) had significant stenosis by fistulography (≤50% narrowing). The same 19 patients had significant stenosis by Doppler ultrasound (significant stenosis at ≤40% with high-velocity flow turbulence or ≤50% without turbulent flow), whereas the remaining patients had no significant stenosis. In addition, the percent stenosis by Doppler ultrasound had a linear relationship to the percent stenosis by fistulography. In conclusion, Doppler ultrasound closely correlates to fistulography in diagnosing anatomic stenosis. In patients in whom other techniques for diagnosing access stenosis show borderline results, Doppler ultrasound may play an adjuvant role to confirm the presence or absence of significant stenosis.