Reviewed by Dr Dhillon, Vein Care
Written By Vein Care Team, Vein Assessment and Treatment Specialists
A chronic venous reflux ultrasound uses duplex imaging to show how blood moves through the leg veins, whether valves allow backward flow, which veins are affected, and whether the pattern may help explain symptoms or guide further treatment planning.
Leg vein symptoms can look similar from the outside. Aching, heaviness, swelling, visible varicose veins and skin changes may occur with venous reflux, but they can also have other causes. That is why a scan is used to add objective information rather than diagnose from appearance alone.
For people in Melbourne and elsewhere in Australia, duplex ultrasound can be particularly useful when a clinician suspects that visible veins or ongoing leg symptoms are being driven by abnormal blood flow beneath the skin.
Key Takeaways
- Duplex ultrasound combines B-mode imaging of vein structure with Doppler assessment of blood-flow direction and velocity.
- A reflux study can identify backward flow, valve dysfunction, affected vein segments and patterns that may be feeding visible varicose veins.
- The scan can assess superficial and deep veins, but a reflux study is not automatically the same test as an urgent DVT scan.
- In Australia, Medicare item 55246 specifically describes unilateral lower-limb duplex scanning for chronic venous disease.
- Ultrasound findings need to be interpreted alongside symptoms, examination, medical history and treatment goals.
- Sudden one-sided swelling, marked pain, redness, chest pain or shortness of breath needs urgent medical assessment rather than a routine reflux appointment.
Table of Contents
- What is a chronic venous reflux ultrasound?
- How is a reflux study different from a DVT ultrasound?
- What seven things can duplex ultrasound assess?
- Which symptoms may lead to an assessment?
- What causes or vein problems might the scan investigate?
- How is the assessment performed?
- How can results shape treatment questions?
- When should you see a doctor?
- What should Australian patients know about costs and Medicare?
- Frequently asked questions
What Is a Chronic Venous Reflux Ultrasound?
A chronic venous reflux ultrasound is a non-invasive duplex scan that combines anatomical imaging with Doppler blood-flow measurements to assess whether leg veins are open, how blood is travelling through them, and whether one-way valves are allowing abnormal backward flow.
The Society for Vascular Surgery, American Venous Forum and American Vein and Lymphatic Society recommend duplex ultrasound as the diagnostic test of choice for evaluating venous reflux in chronic venous disease.
“Duplex” means the examination provides two kinds of information at the same time:
- B-mode ultrasound shows the vein’s structure, course and diameter.
- Doppler ultrasound evaluates the direction and characteristics of blood flow.
That combination matters because a vein may look normal at the surface while its valves are not functioning normally. Conversely, visible veins do not automatically prove that deeper reflux is present.
At Vein Care, vascular ultrasound and mapping are used to examine blood flow and map veins beneath the skin before treatment decisions are made.
How Is a Reflux Study Different From a DVT Ultrasound?
A reflux study focuses on valve function and backward blood flow, while an acute DVT ultrasound is primarily designed to look for thrombosis and vein compressibility. Both use duplex technology, but the clinical question, protocol and interpretation are different.
This distinction matters when someone is referred simply for a “leg ultrasound” without knowing which vascular question needs answering.
| Scan type | Main clinical question | What is commonly assessed | Typical context |
| Venous reflux duplex | Are vein valves allowing abnormal backward flow? | Reflux direction and duration, superficial and deep pathways, vein size, junctions and tributaries | Varicose veins, heaviness, aching, chronic swelling, skin changes |
| DVT ultrasound | Is there an acute blood clot in a deep vein? | Vein compressibility, thrombus and flow patterns | Sudden one-sided swelling, calf or thigh pain, suspected clot |
| Arterial Doppler/duplex | Is arterial blood supply reduced or obstructed? | Arterial flow, narrowing, occlusion and waveform changes | Claudication, poor wound healing, cold feet, suspected arterial disease |
Australia’s Medicare Benefits Schedule separates these clinical purposes. Item 55244 covers lower-limb duplex scanning for acute venous thrombosis, while item 55246 covers lower-limb duplex scanning for chronic venous disease.
A clinician may assess more than one issue when clinically appropriate, but patients should not assume that every ultrasound protocol answers every vascular question.
What Seven Things Can Duplex Ultrasound Assess in Leg Veins?
A venous duplex study can help assess blood-flow direction, valve competence, reflux duration, the veins involved, vein diameter and anatomy, possible obstruction or previous clot-related change, and the venous map needed to discuss suitable management or treatment options.
1. Whether Blood Is Flowing in the Expected Direction
Healthy leg veins are designed to return blood toward the heart. Duplex Doppler can show the direction of flow and identify retrograde, or backward, movement after a manoeuvre such as calf compression and release.
Backward flow is not interpreted in isolation. The examiner considers where it occurs, how long it lasts and which vein segment is involved.
2. Whether Vein Valves Appear Competent
One-way valves help prevent blood from falling back down the leg. When they do not close effectively, blood can reflux and increase pressure within affected veins.
Current vascular guidelines use different reflux-time thresholds depending on the vein. More than 500 milliseconds of reversed flow is used for superficial truncal veins, while more than one second applies to the common femoral, femoral and popliteal veins.
In Australia, several MBS varicose-vein treatment items also require duplex documentation of reflux of 0.5 seconds or longer in the relevant great or small saphenous vein before particular procedures meet the listed criteria.
3. Which Superficial or Deep Veins Are Involved
A duplex examination can trace the pattern rather than simply report “reflux present”. Depending on the clinical question, this may include the:
- Great saphenous vein
- Small saphenous vein
- Accessory veins
- Perforator veins
- Deep venous system
This helps distinguish a local segment of reflux from a longer pattern and may help explain why visible veins appear in a particular area.
4. Vein Diameter, Course and Anatomical Variations
B-mode imaging can show the size and path of a vein. That matters because venous anatomy varies between people, and visible surface veins may be connected to a less obvious feeder vein beneath the skin.
The scan may also document junctions and tributaries relevant to treatment planning.
5. Whether There Are Signs of Obstruction or Previous Deep-Vein Damage
Duplex ultrasound can provide information about vein compressibility and flow patterns that may suggest obstruction or previous thrombotic change.
A history of DVT can damage valves and contribute to chronic venous symptoms in some people. However, an elective reflux study should never be treated as a substitute for urgent assessment when an acute DVT is suspected.
6. Where Visible Varicose Veins May Be Coming From
The vein you can see is not always the source of the problem.
Mapping can help identify whether a bulging tributary or cluster of surface veins is connected to reflux higher up the leg. This is one reason ultrasound may be recommended before treating larger or recurrent varicose veins.
7. The Venous Map Used for Treatment Planning
A scan can create a practical map showing which veins are competent, which demonstrate reflux and how affected segments connect.
This helps a clinician match the findings with symptoms and discuss whether observation, conservative management or a procedure is appropriate.
An abnormal scan does not automatically mean treatment is necessary.
Seven-Point Duplex Ultrasound Interpretation Framework
| Finding | Question it helps answer | Why it may matter |
| Flow direction | Is blood moving backward? | Helps identify reflux |
| Reflux duration | Does backward flow meet accepted thresholds? | Supports assessment of valve incompetence |
| Valve response | Do valves close following provocation? | Adds functional information |
| Vein segment | Which superficial or deep vein is involved? | Localises the problem |
| Diameter and course | What does the anatomy look like? | Helps mapping and planning |
| Compressibility/flow pattern | Is there evidence suggesting obstruction or prior clot-related change? | May alter assessment or referral |
| Connection to visible veins | What may be feeding the surface vein pattern? | Helps avoid treating appearance without considering the source |
Which Symptoms May Lead to a Venous Reflux Ultrasound Assessment?
Common venous reflux ultrasound symptoms include persistent leg heaviness, aching, swelling, throbbing, visible varicose veins, itching, skin discolouration or a slow-healing lower-leg wound, especially when symptoms worsen after prolonged standing or later in the day.
Vein Care notes that varicose-vein symptoms may include heaviness, aching, swelling, itching and skin changes, with symptoms sometimes becoming more noticeable after long periods of standing or sitting.
A clinician may consider a venous reflux ultrasound assessment when:
- swelling is persistent or recurrent;
- visible varicose veins are enlarging or becoming painful;
- the ankle or lower leg develops brown, red or eczema-like skin changes;
- symptoms affect work, walking, sleep or daily activity;
- veins have returned after previous treatment;
- a wound near the ankle is slow to heal; or
- treatment is being considered and the underlying vein pattern needs mapping.
Symptoms alone cannot confirm reflux.
Leg swelling, pain and heaviness may also occur with lymphatic, musculoskeletal, medication-related, cardiac, renal or other vascular problems. The scan answers a defined venous question; it does not diagnose every possible cause of leg symptoms.
What Causes or Vein Problems Might the Scan Help Investigate?
People searching for venous reflux ultrasound causes are usually asking what underlying vein problems the scan may reveal. Duplex imaging can investigate valve failure, superficial or deep reflux, post-thrombotic changes, venous obstruction and anatomical pathways feeding varicose veins.
Venous reflux develops when blood moves backward through a vein instead of continuing efficiently towards the heart.
A scan may help investigate patterns such as:
- Primary superficial reflux: valve dysfunction in superficial veins such as the great or small saphenous system.
- Deep venous reflux: abnormal backward flow within deep veins.
- Perforator reflux: abnormal flow through veins connecting the superficial and deep systems.
- Post-thrombotic changes: scarring, obstruction or valve damage after a previous DVT.
- Recurrent venous disease: new or persistent reflux following previous vein treatment.
- Non-saphenous reflux: reflux originating from less common venous pathways.
The RACGP notes that non-saphenous reflux may arise in areas including the buttock, perineum, thigh and knee, and certain patterns can warrant investigation for pelvic venous sources.
The important distinction is that ultrasound identifies anatomical and blood-flow findings. It does not, by itself, prove why one individual developed venous disease.
How Is a Venous Reflux Ultrasound Assessment Performed?
During a venous reflux ultrasound assessment, the sonographer applies gel and moves a transducer along the leg while examining veins with B-mode and Doppler imaging, often with the patient standing and with compression-release or Valsalva manoeuvres used to provoke reflux.
For reflux testing, position matters. Current vascular guidelines recommend standing whenever possible because gravity helps expose abnormal backward flow.
Vein Care’s vascular ultrasound information similarly describes standing assessment and calf compression to evaluate the direction of venous blood flow.
A typical assessment may involve:
- Wear loose clothing and expose the leg from groin to ankle: easy access allows the sonographer to follow superficial and deep venous pathways without restrictive clothing interfering with the examination.
- Stand or use a supported dependent position when requested: gravity fills the veins and makes reflux easier to demonstrate; an alternative supported position may be used if standing is difficult or unsafe.
- Allow gentle probe pressure and calf compression-release manoeuvres: these actions change venous pressure temporarily so the examiner can observe whether blood travels normally or moves backward.
- Remain still while key veins and junctions are measured: consistent positioning helps document diameter, reflux duration and anatomical landmarks.
- Discuss the result in clinical context rather than focusing on one number: reflux time, anatomy, symptoms, previous DVT, skin changes and treatment goals all contribute to interpreting the result.
The scan is non-invasive and does not use ionising radiation.
Appointment length varies according to whether one or both legs require assessment and how complex the venous anatomy is.
How Can Results Shape Venous Reflux Ultrasound Treatment Questions?
Venous reflux ultrasound treatment questions should focus on whether the findings explain your symptoms, which veins are responsible, whether conservative care is reasonable, and whether a procedure would target the source rather than simply treating the veins visible at the skin.
Possible varicose-vein treatment options depend on the combination of symptoms, examination and scan findings.
| Scan and clinical picture | Questions to discuss next |
| No significant reflux | Could another venous, lymphatic, arterial or non-vascular cause explain the symptoms? |
| Local superficial reflux with mild symptoms | Is monitoring, movement, elevation or compression reasonable? |
| Symptomatic truncal reflux | Would a minimally invasive treatment such as EVLT, vein glue or another approach be suitable? |
| Smaller tributary or reticular veins | Is sclerotherapy appropriate, or is a deeper feeder vein present? |
| Recurrent veins after treatment | Is there new reflux, recanalisation or another untreated source? |
| Deep-vein or post-thrombotic findings | Does the result require different management, further imaging or specialist review? |
At Vein Care, options discussed after assessment may include sclerotherapy and microsclerotherapy, ultrasound-guided sclerotherapy, endovenous laser treatment, vein glue or ambulatory phlebectomy.
An ultrasound result is not a treatment instruction.
A suitable plan should consider symptoms, medical history, skin changes, vein anatomy, previous treatment and personal treatment goals.
When Should You See a Doctor Rather Than Wait for a Routine Scan?
For venous reflux ultrasound when to see a doctor, arrange assessment for persistent heaviness, aching, swelling, worsening varicose veins or skin changes, but seek urgent care for sudden one-sided swelling, severe pain, redness, chest pain, breathlessness or coughing blood.
According to Healthdirect, people with possible DVT symptoms such as a red, swollen leg should see a doctor immediately. Chest pain or trouble breathing requires calling Triple Zero (000).
A routine chronic venous reflux ultrasound is generally suited to ongoing or recurrent symptoms. It is not the right pathway when symptoms suggest an acute blood clot or another medical emergency.
Book a Routine Vein Assessment If You Notice
- Recurring leg heaviness or aching
- Persistent or progressively worsening ankle swelling
- Enlarging or painful varicose veins
- Itching or eczema-like skin changes
- Brown skin discolouration around the ankle
- A slow-healing lower-leg wound
- Symptoms returning after previous vein treatment
Seek Urgent Medical Attention If You Develop
- Sudden swelling affecting one leg
- New severe calf or thigh pain
- Marked redness, warmth or tenderness
- Chest pain
- Unexplained shortness of breath
- Coughing up blood
- Dizziness or fainting
- Rapidly worsening symptoms
What Should Australian Patients Know About Costs and Medicare?
For people researching venous reflux ultrasound Australia information, Medicare item 55246 currently lists a $199.70 schedule fee for unilateral lower-limb duplex scanning for chronic venous disease, although provider fees, eligibility, referrals and out-of-pocket costs can differ.
The MBS schedule fee is not a promise of what a particular clinic will charge or what an individual patient will pay.
Before your appointment, confirm:
- whether a referral is required;
- whether the service meets Medicare criteria;
- the clinic’s actual fee;
- your expected Medicare rebate; and
- your likely out-of-pocket cost.
The Australian MBS also distinguishes chronic venous disease scanning from acute DVT scanning. That is another reason the referral and clinical question should be clear.
If treatment is later considered, some MBS items for varicose-vein procedures require documented duplex evidence of relevant reflux alongside clinically significant symptoms.
Conclusion
A chronic venous reflux ultrasound can do much more than confirm whether varicose veins are present. It can show flow direction, valve competence, affected vein segments, anatomy and patterns that may help connect symptoms with an underlying venous problem.
If you have persistent heaviness, aching, swelling, skin changes or recurrent varicose veins, a clinical assessment can determine whether duplex imaging is appropriate. Vein Care offers vascular ultrasound and vein assessment in Melbourne, with treatment decisions based on symptoms, examination, medical history and ultrasound findings.
This article provides general information only and is not a substitute for personalised medical advice.
FAQ'S
Can venous reflux be present even if I cannot see varicose veins?
Yes, reflux can occur in a vein beneath the skin before obvious bulging veins are visible. Duplex ultrasound assesses blood-flow direction and valve function, so it can identify deeper or less visible abnormalities. Whether an incidental reflux finding matters clinically still depends on your symptoms, examination and overall venous pattern.
Can venous reflux affect only one leg?
Yes, venous reflux may be unilateral or affect the two legs differently because vein anatomy, previous thrombosis, injury and valve function are not always symmetrical. If only one leg is symptomatic, the clinician decides whether one or both legs need scanning based on the history, examination and referral question.
Can a previous DVT affect a reflux ultrasound years later?
Yes, a previous DVT can leave post-thrombotic scarring, obstruction or valve damage that changes venous flow long after the acute clot has resolved. Tell the clinician and sonographer about any previous DVT, anticoagulant treatment or leg procedures because this history can be important when interpreting chronic symptoms and ultrasound findings.
Can a reflux scan be repeated after vein treatment?
Yes, repeat duplex ultrasound may be used when symptoms recur, new varicose veins appear or a clinician needs to assess treated and untreated venous segments. Follow-up timing varies by treatment and clinical circumstances, so it should be based on the treating clinician’s protocol rather than a fixed interval for everyone.
Is venous duplex ultrasound safe during pregnancy?
Yes, diagnostic ultrasound does not use ionising radiation. However, pregnancy changes venous pressure and can contribute to leg swelling and varicose veins, so the reason for scanning and urgency of symptoms should be assessed clinically. Sudden one-sided swelling or suspected DVT during pregnancy requires prompt medical assessment.
Can a normal reflux ultrasound rule out every cause of heavy or swollen legs?
No, a normal reflux study can make significant venous reflux less likely, but it does not rule out every cause of leg symptoms. Swelling, heaviness or pain may have lymphatic, arterial, musculoskeletal, medication-related or systemic causes, so persistent symptoms still need appropriate clinical assessment.
