Sonographers should follow a standard imaging protocol. A complete evaluation includes B-mode imaging, spectral Doppler analysis, and color Doppler imaging of all accessible portions of the hemodialysis access.

Throughout each examination, the sonographer or examiner should:

• Observe sonographic characteristics of normal and abnormal tissues, structures, and blood flow, allowing necessary adjustments to optimize exam quality
• Assess and monitor the patient’s physical and mental status, allowing modifications to the procedure plan according to the patient’s clinical status
• Analyze sonographic findings to ensure that sufficient data is provided to the physician to direct patient management and render a final diagnosis
• Accurately annotate B-mode, color and spectral Doppler images

Doppler is used primarily to document patency of the vessels and access, as well as, identify any areas of stenosis in the inflow artery, anastomosis, within the access or in the outflow vessels.

• Doppler spectral analysis is performed in the sagittal plane.
• Velocity measurements should be obtained from a longitudinal plane at an angle of 60° parallel to the direction of the blood flow/vessel walls.
  • Maintain a Doppler angle between 45° and 60° whenever possible. Angles greater than 60° must be avoided.
  • Doppler angles less than 45° may be necessary due to patient anatomy.
  • To obtain peak velocity, utilize color Doppler to note areas of concern and “walk” the spectral Doppler cursor throughout these areas. Post-stenotic turbulence should be documented when present.
• When a stenosis is identified, velocities should be documented proximal to, within, and distal to the stenosis.
• Flow volumes should be calculated and used to determine fistula maturation.
• Functional disorders can also be identified using flow volumes.

Arteriovenous Fistula

The standard exam for an arteriovenous fistula includes assessment of the inflow (afferent) artery, arteriovenous anastomosis, and outflow (efferent) vein.

• Obtain peak systolic (PSV) and end diastolic (EDV) velocities at least 2 cm cephalad to the arteriovenous anastomosis
• Measure flow volume, approximately 2cm cephalad to the arteriovenous anastomosis
  • Obtain diameter on B-Mode image
  • Optimize spectral window and obtain Time-Averaged Mean Velocity (TAMV)
    • Open sample volume to include entire diameter of vessel
    • Use a 60-degree angle
    • Measure 2-3 cardiac cycles

• Obtain PSV and EDV
  • Compare to the PSV obtained in the afferent artery
• Obtain diameter measurement on B-mode image
  • Note any areas of narrowing or abnormality

• Obtain transverse diameter measurements on B-mode image
  • Proximal, mid, distal outflow vein
    • Include additional measurements at areas of abnormality (e.g., narrowing, wall thickening)
    • Note venous tributaries that may decrease fistula maturation
• Measure depth (skin line to top of vessel) when indicated for fistula maturation
• Note any extrinsic findings (hematoma, seroma, aneurysm, pseudoaneurysm)
• Measure flow volume, approximately 2cm cephalad to the arteriovenous anastomosis
  • Select the mid-portion of the vein in an area that is straight and non- tapering
  • Obtain diameter on B-Mode image
  • Optimize spectral window and obtain Time-Averaged Mean Velocity (TAMV)
    • Open sample volume to include entire diameter of vessel
    • Use a 60-degree angle
    • Measure 2-3 cardiac cycles
• Significant stenosis along the efferent vein is indicated when PSV doubles along contiguous segments.
  • Obtain PSV and EDV proximal to, within, and distal to stenosis
  • Follow the venous outflow to its origin
    • The cephalic and basilic vein confluence with the deep venous system are common sites for stenosis

Arteriovenous Graft

The standard exam for an arteriovenous graft includes assessment of the arterial inflow, arterial anastomosis, graft body, venous anastomosis, and outflow vein.

• Obtain PSV and EDV velocities at least 2 cm cephalad to the arterial anastomosis

• Obtain PSV and EDV
• Obtain diameter measurement on B-mode image
  • Note any areas of narrowing or abnormality

• Obtain PSV and EDV along the body of the graft
  • Include arterial side, loop end, and venous side for a loop graft
  • Include serial segments along the length of a straight graft
• Flow volume measures are obtained from the arterial and venous side of a loop graft and within the mid-portion of a straight graft
  • Obtain diameter on B-Mode image
  • Optimize spectral window and obtain Time-Averaged Mean Velocity (TAMV)
    • Open sample volume to include entire diameter of vessel or graft
    • Use a 60-degree angle
    • Measure 2-3 cardiac cycles
• Include diameter measurements from any areas of narrowing or abnormality

• Obtain PSV and EDV
• Obtain diameter measurement on B-mode image
  • Note any areas of narrowing or abnormality

• Evaluate for any areas of abnormality using B-mode, color and spectral Doppler or according to facility-specific protocol.

Additional Images

• B-mode, color, and/or spectral Doppler images may be obtained of the internal jugular, innominate, subclavian, and/or axillary veins to evaluate for a central venous obstruction.

Stents may be present in the hemodialysis access (arterial inflow, graft, or outflow vein). To assess stent patency:

• Measure PSV and EDV proximal to, within, and distal to the stent.

• Digit discoloration, complaints of numbness, or pain in the hand suggests a steal phenomenon may be present
• Document arterial flow beyond the arterial anastomosis with spectral Doppler waveforms
• Digital waveforms and pressures may be obtained using physiologic equipment to further quantify flow to the hand and digits.
  • Additional maneuvers may include compression of the hemodialysis access with arterial flow documentation to assess for normalization of the arterial flow.