Ultrasound Monitoring of AV Fistula for Hemodialysis: Mapping, Volume Blood Flow, and Maturation Criteria
Preoperative Mapping
Preoperative vascular mapping is associated with a higher success rate of fistula formation (Diagnostic Ultrasound Vascular, 2025). The study evaluates vessel caliber, presence of stenosis, and vascular calcifications. Dimensional criteria:
| Vessel | Minimum Diameter |
|---|---|
| Artery for AVF formation | ≥2 mm |
| Vein for AVF formation | ≥2.5 mm |
| Vein (after dilation) | ≥2.5 mm |
A tourniquet or blood pressure cuff is used on the proximal part of the arm for vein dilation. The room should be warm to prevent vasoconstriction in a cooled patient. Stenosis or thrombosis is described as it affects the fistula's ability to mature.
Maturation Assessment
Ultrasound evaluation for maturity is typically performed approximately 4–8 weeks after fistula formation — for vein arterialization. It is conducted if the fistula is not clearly mature based on physical examination. Technical conditions:
- high-frequency linear transducer;
- patient in a sitting position;
- correction angle for spectral Doppler <60°;
- measurement of blood flow in the draining vein ~10 cm from the anastomosis;
- averaging over at least 3 cardiac cycles;
- tourniquet if necessary.
Approximately 70% of formed fistulas mature and can be used for dialysis, although many require intervention to achieve maturity (Diagnostic Ultrasound Vascular, 2025). Prediction of clinical maturation based on postoperative ultrasound measurements is described in the HFM study (Robbin ML et al., J Am Soc Nephrol, 2018).
Volume Blood Flow and Pathology
The assessment of significant stenosis of dialysis access by duplex ultrasound and the question of the predictive significance of blood flow in the brachial artery in the early postoperative period are considered in specialized studies [specify specific threshold values]. Symptomatic steal syndrome may occur, causing numbness and tingling in the hand, especially during dialysis; it is assessed by duplex ultrasound. A separate group of pathologies includes aneurysms and pseudoaneurysms of dialysis access (Mudoni A et al., Clin Kidney J, 2015).
The standardized protocol for postoperative assessment of hemodialysis access is outlined in the AIUM practice parameter (2024 Revision).
Frequently asked questions
When should ultrasound be performed to assess fistula maturation?
Usually approximately 4–8 weeks after formation to allow time for vein arterialization. It is conducted if the fistula is not clearly mature on physical examination.
Where to measure blood flow in the draining vein?
At a distance of ~10 cm from the anastomosis, averaging over at least 3 cardiac cycles and with a correction angle for spectral Doppler <60°.
What are the minimum vessel diameters needed for AVF formation?
Artery — at least 2 mm, vein — at least 2.5 mm; vein after dilation also ≥2.5 mm (Diagnostic Ultrasound Vascular, 2025).
What is the maturation rate of formed fistulas?
About 70% of fistulas mature and can be used for dialysis, but many require intervention to achieve maturity.
Why is preoperative mapping necessary?
It is associated with a higher success rate of fistula formation; vessel caliber, stenosis, and calcifications are evaluated.