Diagnostic Ultrasound - Abdomen and Pelvis

Transplant Renal Artery Stenosis
Diagnoses: Kidney Transplant
IMAGING
• Most commonly at arterial anastomosis
• Focal elevation of peak systolic velocity (PSV) with poststenotic
turbulence
• Color aliasing and soft tissue vibration at area of stenosis
• Elevated PSV in stenotic area > 250-300 cm/sec
• Secondary sign: Tardus parvus intrarenal waveforms = slow
systolic upstroke and decreased peak velocity
○ Low resistive index (RI) < 0.5
• Color, power, spectral Doppler US is screening modality for
transplant renal artery stenosis (TRAS)
• Careful attention to Doppler angle to ensure accurate PSV
measurements
• Supplemented by CTA and MRA
○ More comprehensive vascular evaluation including iliac
arteries and aorta
• Catheter angiography is gold standard but is invasive with
potential complications
KEY FACTS
TOP DIFFERENTIAL DIAGNOSES
• Abrupt renal artery curves and kinks
• Pseudo renal artery stenosis
PATHOLOGY
• Surgical injury during harvesting or transplantation
• Immune mediated vascular damage from rejection
• Older renal donors
• Predisposing recipient factors: Atherosclerosis, diabetes,
obesity, increasing age
CLINICAL ISSUES
• 2-10% of transplants
• Present with hypertension, acute renal failure or
progressive decline in renal function
• May have bruit in vicinity of transplant/iliac artery
• Increased patient morbidity and mortality if untreated
(Left) Longitudinal spectral
Doppler ultrasound shows the
main renal artery 3 weeks
after cadaveric renal
transplant in an 82-year-old
man. The peak systolic velocity
ſt in the main renal artery
exceeds 400 cm/s with aliasing
of the Doppler spectrum
indicating a significant artery
stenosis. Renal function was
poor. (Right) Longitudinal
spectral Doppler ultrasound of
the same patient with renal
artery stenosis shows the peak
systolic velocity of the
external iliac artery ſt was
151 cm/s with a renal artery
to iliac artery ratio > 2.6.
(Left) Digital subtraction
angiography of the same
patient confirms stenosis at
the renal artery anastomosis
estimated to be > 80%.
This was successfully
angioplastied. (Right) Doppler
ultrasound of an interlobar
artery in a renal transplant
with renal artery stenosis
shows tardus parvus ſt with a
low resistive index of 0.46.
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