Diagnostic Ultrasound - Abdomen and Pelvis

Renal Transplant Arteriovenous (AV) Fistula
Diagnoses: Kidney Transplant
TERMINOLOGY
• Abnormal direct communication between artery and vein
IMAGING
• Usually in renal parenchyma; may be extrarenal
• Not usually visible when small
• Large arteriovenous fistulas (AVF) are serpiginous vessels
• Feeding artery shows high-velocity, low-resistance
waveform with spectral broadening
• Pulsatile arterialized flow in draining vein when large
• Best detected when background normal color flow is
suppressed by using higher Doppler scale
• Perivascular tissue vibration producing color in adjacent
tissues
• Catheter angiography is gold standard for diagnosis, allows
endovascular treatment
TOP DIFFERENTIAL DIAGNOSES
• Pseudoaneurysm
KEY FACTS
• Renal artery stenosis
PATHOLOGY
• Complication of percutaneous transplant biopsy or
insertion of nephrostomy
CLINICAL ISSUES
• Post-biopsy incidence: 1-18%
• Most asymptomatic or present with hematuria
• 50% disappear within 48 hours; 70% resolve spontaneously
within 1-2 years
• Observation with serial ultrasound for majority
• 30% symptomatic and persistent
• Treated with superselective embolization of feeding artery
(Left) Longitudinal ultrasound
of the lower pole of a renal
allograft shows a large,
serpiginous, anechoic
structure st extending from
the sinus to the cortex. (Right)
Longitudinal color Doppler
ultrasound of the same
patient shows that the
serpiginous structure st fills in
with color, representing an
intrarenal arteriovenous
fistula. This was confirmed
with spectral Doppler.
(Left) Longitudinal power
Doppler ultrasound of a renal
allograft with a lower pole
arteriovenous fistula ſt
obscured by perivascular color
bleeding shows that there is
surrounding tissue vibration
st. (Right) Longitudinal
spectral Doppler of an
arteriovenous fistula ſt
presenting as a small area of
increased color flow relative
to background shows a
characteristic high-velocity,
low-resistance turbulent
waveform.
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