Colour Doppler is an ultrasound that shows the direction and speed of blood flow. It detects blocked or narrowed arteries, clots in veins and leaking vein valves without needles or radiation.
Doppler studies
- Lower and upper limb venous Doppler — venous reflux mapping, DVT
- Peripheral arterial Doppler — leg pain on walking, diabetic foot, non-healing ulcers
- Carotid & vertebral Doppler — stroke risk, TIA, dizziness
- Renal artery Doppler — hypertension
- Obstetric / fetal Doppler — growth restriction and high-risk pregnancy
- Scrotal, penile and portal venous Doppler
- AV fistula assessment for dialysis
Frequently asked questions about Colour Doppler
What is the difference between ultrasound and Doppler?
A normal ultrasound shows the structure of organs; Doppler adds information about blood flow in vessels.
Do I need to prepare for a Doppler?
Limb and carotid Dopplers need no preparation. Renal and abdominal Dopplers may need fasting for a few hours.
Page reviewed by the radiology team at Kansal Diagnostic Centre · Updated October 2026