Criteria for diagnosis and grading of stenosis in spectral PW Doppler ultrasound.

Table 2: Criteria for diagnosis and grading of stenosis in spectral PW Doppler ultrasound.

	< 75% Stenosis	≥ 75% Stenosis	Occlusion
Spectral waveform at the examined segment	Triphasic No or minimal broadening spectrum	Monophasic Broadening spectrum	No flow detected
Spectral waveform from distal point to the examined segment	Normal	Monophasic with reduce velocity	Monophasic with reduce velocity or No flow detected
PSV at the examined segment	No increased or Increase in PSV < two-fold relative to the proximal segment	Increase in PSV ≥ two-fold relative to the proximal segment	No flow detected