What is the protocol for writing an Arteriovenous Fistula (AVF) aneurysm assessment order?

AVF Aneurysm Assessment Order Protocol

When ordering an assessment for an AVF aneurysm, begin with duplex Doppler ultrasound as the primary imaging modality, documenting specific measurements of aneurysm size, location, associated stenosis, and flow parameters, followed by fistulography if intervention is being considered or if ultrasound findings are inconclusive. 1

Essential Components of the Assessment Order

Primary Imaging: Duplex Doppler Ultrasound

Order duplex Doppler ultrasound with the following specific parameters:

• Aneurysm diameter measurement - Document exact size in centimeters, as dilatation exceeding three times the native vessel diameter defines a true aneurysm 2
• Aneurysm location - Specify whether juxta-anastomotic, mid-outflow vein, or distal outflow vein 2
• Presence of thrombus within the aneurysm - Critical for risk stratification 2
• Associated stenosis evaluation - Both pre-aneurysmal and post-aneurysmal stenotic lesions must be identified 1, 2
• Access flow rate measurement - Flow rates are essential for determining hemodynamic significance 1
• Intra-access pressure assessment - Elevated pressure contributes to aneurysm formation 1
• Depth from skin surface - Document distance to assess rupture risk and skin integrity 1
• Vessel diameter of non-aneurysmal segments - For comparison and surgical planning 1

Physical Examination Documentation Requirements

Include specific clinical findings in your assessment order:

• Skin integrity over the aneurysm - Thin, shiny skin indicates impending rupture risk 1
• Irregular or dilated areas - Document all aneurysmal formations along the access 1
• Pulsation characteristics - Abnormal pulsations suggest underlying stenosis 1
• Thrill quality - Weak, discontinuous, or systolic-only thrill indicates dysfunction 1
• Compressibility - Difficult-to-compress segments suggest stenosis 1
• Evidence of previous cannulation trauma - "One-site-itis" pattern 1

Secondary Imaging: Fistulography

Order fistulography when:

• Duplex ultrasound suggests hemodynamically significant stenosis requiring intervention 1
• Endovascular treatment is being planned 1
• Complete anatomic mapping is needed for surgical planning 1
• Central venous stenosis or occlusion is suspected 2

Specify the approach:

• Retrograde venous access is standard 1
• Direct arterial puncture (3F micropuncture) may be needed if retrograde access fails 1

Critical Measurements to Document

Size Documentation Protocol

Explicitly request measurement documentation in the medical record, as this improves awareness and intervention rates among all stakeholders 1:

• Absolute diameter in centimeters
• Ratio to native vessel diameter (>3:1 defines aneurysm) 2
• Length of aneurysmal segment
• Distance from arterial anastomosis

Flow Parameters

Request quantitative flow measurements:

• Absolute flow rate in mL/min 1
• Comparison to baseline access flow
• Peak systolic velocity
• Flow patterns suggesting stenosis

Risk Stratification Elements

The assessment order should specifically address:

• Rupture risk indicators - Thin overlying skin, rapid growth, size >3 cm 1, 2
• Functional compromise - Inadequate straight segments for two-needle cannulation 1
• Associated complications - Venous hypertension, steal syndrome, high-output cardiac failure 2
• Infection risk - Skin breakdown, previous cannulation site infections 1

Common Pitfalls to Avoid

Do not order generic "AVF ultrasound" - This lacks the specificity needed for aneurysm assessment. Always specify aneurysm protocol with size documentation 1

Do not delay imaging when clinical examination reveals concerning features - Thin skin, rapid enlargement, or symptoms warrant immediate assessment 1, 2

Do not omit central venous evaluation - 9% of patients with AVF aneurysms have central venous stenosis or occlusion that affects management 2

Do not forget to document cannulation patterns - Repeated single-site cannulation causes localized aneurysms and must be identified to prevent recurrence 1

Order Template Structure

A complete AVF aneurysm assessment order should include:

1. Primary study: Duplex Doppler ultrasound of [specify arm] AVF with aneurysm protocol
2. Specific measurements required: Aneurysm diameter, location, thrombus presence, associated stenosis, flow rate, intra-access pressure
3. Clinical indication: Document symptoms (pain, skin changes, venous hypertension, functional compromise) 2
4. Comparison: Request comparison to prior studies if available
5. Urgency: Specify if stat/urgent based on clinical findings (thin skin, rapid growth, symptoms)
6. Secondary imaging: Note if fistulography will be needed for intervention planning

For intervention planning, add: Request vascular surgery or interventional radiology consultation with imaging results for treatment decision-making 1, 2