Background: Stenoses of vascular accesses are leading factors limiting access survival. Besides physical examination, screening of access stenoses is based mainly on the "dysfunction hypothesis", which states that progressive stenosis causes graft dysfunction, such as decreased flow. We tested whether Doppler ultrasonography could detect a number of clinically hidden access stenoses in otherwise well-managed patients. Indications from clinical evaluation regarding the presence of stenosis were compared with ultrasound findings.
Methods: We made 258 examinations in 193 patients. Whole-length morphological ultrasound examinations of vascular access were done with a 7.5 MHz linear array transducer. The combination of > 50% stenosis in B-mode and at least doubling of peak systolic velocity was the criterion for significant stenosis. We compared the specificity and sensitivity of clinical diagnosis or ultrasound.
Results: The sensitivity and specificity of the clinical diagnosis of stenosis were 35.8% and 92.8%, respectively.
Conclusions: A considerable number of otherwise appropriately managed hemodialysis patients suffer from significant access stenosis. Wider use of Doppler ultrasonography would increase the proportion of clinically hidden stenoses diagnosed in time and thus might prolong access patency. Clinical suspicion of access stenosis is highly specific and such patients should be examined directly by angiography.