Atherosclerotic stenosis at the ostium in older patients, fibromuscular dysplasia (string of beads, mid-distal) in young women — Doppler measures the peak systolic velocity and renal–aortic ratio, CTA shows the anatomy.
Orient first
- Doppler: PSV > 180–200 cm/s and renal–aortic ratio > 3.5 suggest ≥ 60% stenosis (verify local criteria).
- Intrarenal tardus–parvus waveform (acceleration time > 70 ms) is an indirect sign.
- FMD: multifocal (string of beads) — also look at carotid and vertebral arteries.
Acquire the study
- Curvilinear probe, fasted; colour and spectral Doppler of the aorta, main renal arteries (ostium to hilum) and segmental arteries.
The manoeuvre
- Aortic PSV at the level of the renal arteries in cm/s.
- Main renal artery PSV along its length; renal–aortic ratio.
- Post-stenotic turbulence.
- Segmental arteries: acceleration time in ms and resistive index.
- Kidney length in cm on both sides.
What confirms it
- Direct Doppler criteria or ≥ 60–70% stenosis on CTA with haemodynamic support.
What licenses you to exclude it
- Normal velocities along the whole artery with normal intrarenal waveforms make significant stenosis unlikely.
The classic misread
- Missing an accessory renal artery.