Reliability of Ultrasound Duplex for Detection of Hemodynamically Significant Stenosis in Hemodialysis Access

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Objective: This study aims to evaluate the accuracy of AVF and AVG duplex ultrasound (US) compared to angiographic findings in patients with suspected failing dialysis access.Materials and Methods: From July 2008 to December 2010, US was performed on 35 hemodialysis patients with 51 vascular accesses having clinical feature or dialysis parameter suspicious of access problem. Peak systolic velocity ratio of ≥2 was the criteria for diagnosing stenosis ≥50%. Fistulogram was performed in all these patients. Results of US and fistulogram were compared using Kappa and Receiver Operator Characteristic (ROC) analyses.Results: In 51 accesses (35 AVF, 16 AVG), US diagnosed significant stenosis in 45 accesses according to the criteria and angiogram confirmed 44 significant stenoses. In AVF lesions, Kappa was 0.533 with 93.3% sensitivity and 60% specificity for US whereas in AVG lesions, Kappa was 0.636 with 100% sensitivity and50% specificity. Overall Kappa value of 0.56 meant fair to good agreement. ROC demonstrated area under the curve being 0.79 for all cases and was significant (p= 0.016). Using the ≥50% criteria for stenosis diagnosed by US yielded the best sensitivity (95.5%) and specificity (57.1%).Conclusion: Duplex ultrasound study, using ≥50% criteria, is a sensitive tool for stenosis detection in patients with suspected failing AVF and AVG.