**3.2 Postoperative evaluation of AVF**

According to National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI), clinical examination remains the key to determination of maturation. However, USG and CDI prove reliable for surveillance assessment and to find causes of immaturation and complications if any. USG evaluation of AVF is done with high resolution (≥9 mHz) probe without tourniquet. Minimal pressure is applied while scanning with generous amount of ultrasound gel for proper visualization.

The evaluation of AVF starts with clinical examination, where the AVF is palpated for a possible thrill which denotes its proper working. Scanning is then initiated from the feeding artery in axial and Saggital views. The artery is traced towards the draining vein and overall anatomy is evaluated. Feeding artery adjacent to AVF is examined for any wall thickening, lumen patency and areas of stenosis in B mode scanning. Color doppler study is used to see uniform color filling and aliasing color flow like AVF (**Figure 8**). Pulse wave doppler is used for noting biphasic waveform in artery instead of usual Triphasic waveform seen in preoperative artery (**Figure 9**). Peak systolic velocity (PSV) in the feeding artery increases to about 9 to 10 fold in comparison to pre AVF state in mature AVF. PSV is measured in the artery at the level of AVF and 2 cm proximal to it.

*Hemodialysis AV Fistula: What a Radiologist Should Know? DOI: http://dx.doi.org/10.5772/intechopen.100485*

#### **Figure 8.**

*(a) CDI image showing working AVF with colorailising, (b) CDI study showing normal spectral waveform with high PSV within the AVF, (c) normal post AVF biphasic waveform in brachial artery, (d) mild dilated cephalic vein with patent lumen.*
