Color, power, spectral Doppler US is screening modality for transplant renal artery stenosis

Stenosis occurs most commonly at arterial anastomosis but can occur along length of artery

Focal elevation of peak systolic velocity (PSV) > 250-300 cm/s at stenosis with poststenotic turbulence

Color aliasing and soft tissue vibration at area of stenosis

Renal artery to Iliac PSV ratio > 1.8-3.5

Secondary sign: Tardus parvus intrarenal waveforms = slow systolic upstroke and decreased peak velocity

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  Decreased acceleration index < 3 m/s² and increased acceleration time > 0.1 s in segmental arteries

  
  
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  Low resistive index (RI) < 0.5

Catheter angiography is gold standard for diagnosis and allows treatment with angioplasty or stenting

Abrupt renal artery curves and kinks

Pseudorenal artery stenosis from iliac stenosis

Systemic hypotension may cause low RI

Surgical injury during harvesting or transplantation

Immune-mediated vascular damage from rejection

Older donors and recipients, atherosclerosis, diabetes

2-10% of transplants

Present with hypertension, acute renal failure or progressive decline in renal function, bruit

Careful attention to Doppler angle to ensure accurate PSV measurements

Compare highest peak renal artery velocity to iliac artery velocity

Curves and kinks may elevate velocities, mimicking stenosis