Vascular access problems remain the vulnerable point of modern HD . For evaluation of access dysfunction, the initial, most practical, and cost-effective method is physical examination . US confirm the results of physical examination such as inflow stenosis and outflow stenosis. Moreover, it provides important information about the functional severity like brachial artery flow rates [14, 15]. By combining the findings of US and physical examination, the treatment methods can be determined, such as angioplasty, revision surgery, or conservative management . Moreover, Doppler US shortens angioplasty time, as it gives information on the stenosis site . Thus, by the use of US, more clinical needs are satisfied .
The present study demonstrated that, during the first 11 months of newly created AVFs, a great percentage of patients encounter cannulation related complications were significantly higher in primary than tertiary centers of hemodialysis.
In this study, we evaluated the clinical utility of CDUS for early detection of complications in AV dialysis access. We found that the number of female patients exceeded that of males, with 36 female patients and 24 male patients, representing 60 and 40% of all patients, respectively. This correlates with the findings of the previous studies who found that fistulas are less likely to be usable for dialysis in female than in male patients .
Among our study population, the most common shunt complication associated with HD was access to thrombosis (n = 5, 16.6% in primary centers and n = 4, 13.3% in tertiary centers). Thrombosis is usually located in the arteriovenous anastomosis of the AVF. In our study, thrombosis was detected at the venous side of the fistula in most cases; diagnosis of thrombosis was established by absence of flow using color or pulsed Doppler together with hypoechoic or echogenic thrombus filling the lumen.
Stenosis of HD vascular access is common and may lead to thrombosis and the loss of the access. Thus, detection of stenosis in AVF before thrombosis could offer a strategy to improve AVF survival by early intervention . Stenosis in AVF develops more frequently in juxta-anastomotic location, up to 4 cm from the anastomosis . Among 4 patients diagnosed with stenosis, one cases had post-fistula stenosis, three cases had stenosis at the anastomotic site. This was in accordance with the finding of Tirinescu et al. , who performed a large observational study on 97 patients, and reported juxta-anastomotic localization of stenosis in most cases, in the forearm, and in the upper arm AVF equally.
Clinically pseudoaneurysms are diagnosed by the presence of a pulsatile mass with systolic murmur. However, CDUS is particularly suitable to determine the extent of the aneurysm and to demonstrate thrombotic material within the aneurysmatic sac . Out of the examined cases in our study, 6 patients had pseudoaneurysm (12%), 4 at the venous side of the AVF, 1 at the site of anastomosis, and 1 at the arterial side, which is relatively rare. Puncture of an AVF either as part of standard dialysis needling or from intervention can result in prolonged bleeding and pseudoaneurysm formation. However, the mechanism of formation of true aneurysms in AVFs is less clear. This is may be attributed to also to repeated needling with consequent development of multiple small fibrous scars in the vessel wall that expand with time and result in localized aneurysmal areas [22, 23].
Tenderness and erythema along the access can indicate infection. An untreated access infection may lead to bacteremia, sepsis, hemorrhage, and, if left untreated, possible death. In this study, 4 patients 13.3% in primary centers had an infected AVF, and only one patient had an infected AVF 3.3% in tertiary centers, due to the use of complete antiseptic measures in tertiary centers.
Venous hypertension results from arterialization of the venous system proximal to an arteriovenous fistula with central venous occlusion . Our study included 2 patients with venous hypertension (4%) due to central venous stenosis.
The CDUS findings in this series were helpful to determine further therapeutic management in patients with AV dysfunction.
The limitation of this study is the relatively small number of patients with selection bias including only patients with suspected AV dysfunction on physical examination. A larger study including all patients for surveillance of AVF is recommended.