A complete guide to your renal artery duplex ultrasound — a scan that evaluates blood flow to your kidneys, often the missing piece in difficult-to-control hypertension.
Many patients have never had this type of scan before. Here is exactly what will happen — no surprises.
Completely painless and non-invasive. Ultrasound uses sound waves — no radiation, no needles, no discomfort. Most patients find the experience relaxing.
The exam begins with you lying on your back. The sonographer uses the liver and spleen as acoustic windows to visualize the renal arteries near their origin from the aorta.
The aorta is identified at the level of the renal arteries. Flow velocity in the aorta provides the denominator for the renal-to-aortic ratio calculation.
The right renal artery is traced from its origin on the aorta to the kidney. Velocity measurements are taken at the origin, mid-artery, and hilum.
You may be asked to roll slightly to your right side to improve visualization of the left renal artery, which lies deeper and is often more challenging to image.
Each kidney is measured in length and assessed for structural appearance. A kidney significantly smaller than the other often indicates chronic reduced blood flow on that side.
Your cardiologist report includes peak systolic velocities, renal-aortic ratios, kidney measurements, and clinical interpretation — often with specific implications for blood pressure management.
Your cardiologist report is written in plain language, but here are the specific measurements and terms you may encounter — and exactly what they mean.
The most direct measure of stenosis. A velocity above 180–200 cm/s at the renal artery origin is highly suspicious for significant stenosis.
Compares renal artery velocity to adjacent aortic velocity. A ratio above 3.5 is generally considered diagnostic of hemodynamically significant renal artery stenosis.
A measurement of intrarenal blood flow resistance. Elevated values suggest significant parenchymal (kidney tissue) disease that may limit the benefit of treating the artery.
The time for blood flow to reach peak velocity in the intrarenal arteries. A prolonged acceleration time (tardus-parvus pattern) is an indirect sign of proximal renal artery stenosis.
Normal kidney length: 9–12 cm. A kidney more than 1.5 cm smaller than the other is considered significantly asymmetric — a classic sign of chronic ischemic nephropathy.
Renal artery imaging can occasionally be limited by body habitus, bowel gas, or depth. If incomplete, additional fasting or a repeat study with positioning changes may be recommended.
Your report will clearly state whether follow-up is needed and how urgently. Here is what each outcome typically means.
No significant abnormalities. Share your report with your primary care physician. Consider repeat screening in 1–3 years based on your risk profile.
Minor findings that warrant monitoring. Your report will specify follow-up timing and any lifestyle recommendations.
Clinically significant findings requiring physician review. Your report will indicate appropriate urgency.
Findings requiring prompt evaluation. We will contact you directly in addition to delivering your report.
No referral needed. $397 all-inclusive. Results from a board-certified cardiologist within 24–48 hours.