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###1: Maximum Blood Velocity by Ultrasound (Vmax)

Published: August 9, 2026Updated: August 16, 2026

###3: This ultrasound measurement records the highest speed of blood flow detected in the examined blood vessel or heart region. It can help assess blood flow and identify areas of narrowing or abnormal flow.

Quick summary

["###4: Vmax helps evaluate blood flow and may contribute to the detection or monitoring of narrowing or obstruction."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
34141-2
Short code
Vmax US
Synonyms
Vmax US
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
us
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

###5: What the test measures

###6: Vmax is the maximum Doppler ultrasound velocity measured at a specific location. The value depends on the vessel or heart region examined, so it is interpreted together with the rest of the ultrasound study.

###7: How the test is performed

###8: A technician moves a Doppler ultrasound probe over the area being examined. Sound waves are used to estimate the speed and direction of blood flow without requiring an incision.

###9: Why it is used

###10: Clinicians may use Vmax to help evaluate narrowed blood vessels, valve-related flow abnormalities, or other changes in circulation. Other ultrasound findings are generally needed to confirm the cause.

###11: Preparation and results

###12: Preparation varies with the body area being examined; the healthcare provider should give specific instructions. The result is usually reported as a blood-flow velocity and interpreted by a clinician familiar with the complete scan.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

###13: An elevated or reduced Vmax may indicate altered blood flow, but it is not diagnostic by itself. Its significance depends on the location examined, blood-flow direction, accompanying ultrasound findings, symptoms, and the person's overall condition.

Short name

###2: Blood-flow velocity by ultrasound

Frequently asked questions

###14: What does a Vmax result mean?
###15: Vmax describes the highest blood-flow speed measured by ultrasound at the sampled location. A higher or lower value may be associated with a flow abnormality, but the full ultrasound report is needed for interpretation.
###16: Is Vmax the same as blood pressure?
###17: No. Vmax measures the speed of blood flow within a vessel or heart region, whereas blood pressure measures the force of blood against artery walls.
###18: Does a high Vmax always mean that a blood vessel is narrowed?
###19: No. High velocity can occur with narrowing, but it can also be influenced by the vessel's size, flow direction, valve function, measurement location, and other factors. A clinician must interpret Vmax with the complete ultrasound study.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy