Non-thermal vein closure refers to minimally invasive treatments that close an incompetent superficial vein without using the thermal energy used in endovenous laser ablation (EVLA) or radiofrequency ablation (RFA).
The two principal approaches are cyanoacrylate adhesive closure, commonly known as medical vein glue, and mechanochemical ablation (MOCA).
These treatments are sometimes described as non-thermal, non-tumescent (NTNT) techniques because treatment does not depend on heating the vein and usually does not require the extensive tumescent anaesthetic injections used around the target vein during EVLA or RFA.
Current international venous guidelines recognise both thermal and non-thermal ablation as legitimate options for appropriately selected patients with symptomatic saphenous reflux.
However, the fact that a treatment avoids heat does not automatically make it more advanced or more appropriate.
The treatment should still begin with the same principle used throughout modern varicose vein care:
identify the reflux first, then select the technology.
Why Venous Mapping Comes Before Treatment
A patient may request glue treatment because it sounds less invasive than laser.
But before deciding whether glue, MOCA, EVLA or RFA is appropriate, the specialist needs to understand the patient’s venous anatomy.
Duplex Doppler ultrasound identifies the source and extent of reflux, whether the great saphenous vein, small saphenous vein or another superficial pathway is involved, and whether significant tributary varicose veins are also present.
The FDA-approved indication for the VenaSeal cyanoacrylate system itself specifies treatment of symptomatic superficial truncal venous reflux diagnosed by duplex ultrasound.
This is important because non-thermal treatment is still anatomy-dependent treatment.
A photograph may show the visible varicose veins.
Doppler shows what is causing them.
Cyanoacrylate Adhesive Closure / Medical Vein Glue
Cyanoacrylate closure uses a specially formulated medical adhesive delivered through a thin catheter positioned inside the refluxing vein.
Under ultrasound guidance, controlled amounts of adhesive are delivered while external pressure is applied to bring the vein walls together.
The abnormal vein closes and blood is redirected through functioning venous pathways.
Unlike EVLA or RFA, no thermal energy is delivered along the vein.
One of the best-known systems is VenaSeal, which is FDA approved for permanent closure of symptomatic lower-extremity superficial truncal veins such as the great saphenous vein.
Patients should understand that VenaSeal is a brand, while cyanoacrylate closure is the treatment category.
Other adhesive systems may exist in different countries, and they should not automatically be assumed to have identical devices, protocols or clinical evidence.
Why Patients May Prefer Medical Adhesive Treatment
A practical advantage of cyanoacrylate closure is that the vein can be treated without the multiple injections of tumescent anaesthetic normally required around the length of a vein during thermal ablation.
There is also no thermal energy around adjacent tissues.
For selected anatomy, avoiding heat can therefore be useful.
But treatment choice should not be based only on comfort during the procedure.
The specialist also needs to consider vein diameter, location, previous treatment, expected durability and potential treatment-specific complications.
Recent 2026 evidence continues to compare cyanoacrylate ablation directly with established treatments such as radiofrequency ablation, confirming that adhesive closure remains an active contemporary treatment rather than an abandoned technology.
Medical Glue Has Its Own Risks
“No heat” does not mean “no complications.”
Cyanoacrylate treatment can cause inflammatory or phlebitis-like reactions around the treated vein. Hypersensitivity reactions to cyanoacrylate are also an important treatment-specific consideration.
As with other venous interventions, thrombosis and treatment-related extension toward the deep venous system must also be considered in appropriate patients.
The appropriate message for patients is therefore not that glue is safer because it avoids laser.
It is that glue has a different mechanism and a different complication profile.
Mechanochemical Ablation (MOCA)
Mechanochemical ablation uses another non-thermal approach.
Instead of medical adhesive, MOCA combines mechanical injury to the inner surface of the vein with administration of a sclerosant.
A specialised catheter is advanced through the target vein under ultrasound guidance. The device mechanically disrupts the venous lining while sclerosant is delivered.
The combined mechanical and chemical effect encourages closure of the refluxing vein.
Because heat is not used, tumescent anaesthesia along the full treated segment is generally unnecessary.
Examples of MOCA technologies have included ClariVein and Flebogrif-type systems, although their mechanisms are not identical.
Flebogrif, for example, uses a different mechanical catheter design from the rotating-wire mechanism associated with ClariVein.
A prospective multicentre study published in July 2026 continues to evaluate Flebogrif mechanochemical treatment for great saphenous vein incompetence, showing that this remains an active area of venous research.
What Long-Term Evidence Tells Us About MOCA
This is particularly important in a 2026 patient guide.
Early MOCA studies generated considerable interest because treatment avoided both thermal energy and extensive tumescent injections.
Longer follow-up has made treatment selection more nuanced.
Recent seven-year randomized evidence directly comparing MOCA with thermal ablation is now available, making long-term durability an important part of the discussion when MOCA is being considered.
Other long-term studies have also reported that anatomical success after ClariVein can decrease over time.
This does not mean MOCA has no clinical role.
It means patients should not choose it purely because it sounds newer or less invasive.
Short-term procedural convenience and long-term vein durability are different questions.
Medical Glue and MOCA Are Not the Same Treatment
Both are non-thermal techniques, but they should not be presented as interchangeable.
Medical adhesive closes the vein using cyanoacrylate.
MOCA combines mechanical endothelial injury with sclerosant.
They therefore have different mechanisms, materials, contraindications, potential complications and long-term evidence.
When a patient is offered a “non-thermal treatment,” the actual technique should always be specified.
What About HIFU / Echotherapy?
A newer development is High-Intensity Focused Ultrasound (HIFU) treatment of venous reflux.
Unlike EVLA, RFA, glue or MOCA, HIFU aims to treat the target vein from outside the body without introducing a catheter into the vein.
Focused ultrasound energy is directed toward the target venous segment under imaging guidance, producing thermal ablation without a vascular puncture.
This represents a genuinely different concept in varicose vein treatment.
However, it is important not to overstate its current position.
The multicentre VEINRESET pivotal study is evaluating extracorporeal HIFU using the Sonovein system for primary great saphenous vein insufficiency.
Therefore, as of 2026, HIFU is better described as an emerging non-invasive technology rather than being presented alongside EVLA, RFA or established cyanoacrylate closure as a routine first-line treatment everywhere.
This is exactly the kind of technology that should appear in an up-to-date patient guide while still being clearly labelled according to the maturity of its evidence.
Newer Does Not Automatically Mean Better
Varicose vein technology evolves quickly.
New catheters, adhesives, sclerosant-delivery systems, microwave devices and completely non-invasive technologies continue to appear.
Patients may therefore encounter marketing terms such as:
“latest vein treatment”
“no-needle treatment”
“no-heat treatment”
“next-generation vein closure”
or “surgery-free treatment.”
These descriptions may be technically true in part, but they do not answer the most important medical question:
Is that technology appropriate for this patient’s reflux pattern?
Current 2026 comparative evidence still supports both thermal and non-thermal approaches for appropriately selected saphenous incompetence rather than identifying one technology as universally superior.
Can Non-Thermal Treatment Be Combined With Other Treatments?
Yes.
Closing the main refluxing vein does not necessarily treat every visible surface varicosity.
For example, a patient may undergo cyanoacrylate closure of an incompetent great saphenous vein while remaining tributary varicosities are subsequently treated with phlebectomy or sclerotherapy.
The same general principle applies after MOCA.
Treatment can be performed during one treatment pathway or in stages depending on anatomy, symptoms and the response of residual veins.
We should still keep the main “Can Varicose Vein Treatments Be Combined?” section after all four treatment groups so this point is not unnecessarily repeated throughout the page.
Non-Thermal Vein Treatment Abroad
For international patients, non-thermal techniques can be especially attractive because advertising often focuses on shorter procedures, fewer injections and rapid return to activity.
But travelling abroad for “vein glue” before the diagnosis has been established is not appropriate treatment planning.
Available Doppler studies, previous procedures, history of thrombosis, medication and relevant allergies should be reviewed whenever possible.
If current reflux mapping is unavailable, the final choice between cyanoacrylate closure, MOCA, EVLA, RFA, sclerotherapy or surgery may need to be made after vascular examination and Doppler assessment in Türkiye.
Patients should also know exactly which product or device is being used.
A discharge report saying only “glue treatment performed” is less useful than documentation identifying the treated vein, treated segment, technique, device, additional procedures and follow-up plan.
This becomes particularly important if the patient later requires vascular assessment in another country.
What Patients Should Not Assume
Patients should not assume that non-thermal means risk-free.
They should not assume that all vein glues are identical.
They should not assume that glue and MOCA are the same treatment.
They should not assume that avoiding tumescent anaesthesia guarantees better long-term results.
And they should not assume that HIFU or another newly introduced technology is automatically superior because it is newer.
Modern varicose vein treatment is increasingly technology-rich.
But the principle remains remarkably simple:
The treatment should follow the Doppler anatomy, not the marketing name of the device.
Selected References
- Society for Vascular Surgery, American Venous Forum and American Vein and Lymphatic Society. 2023 Clinical Practice Guidelines for the Management of Varicose Veins of the Lower Extremities, Part II.
- U.S. Food and Drug Administration. VenaSeal Closure System – Premarket Approval and Indications for Use.
- Contemporary 2026 comparative evidence evaluating thermal and non-thermal ablation for saphenous vein incompetence.
- Seven-year randomized follow-up comparing mechanochemical and thermal ablation for great saphenous vein insufficiency.
- 2026 prospective multicentre study evaluating Flebogrif mechanochemical ablation for great saphenous vein incompetence.
- ClinicalTrials.gov. VEINRESET pivotal study of extracorporeal HIFU / Sonovein for great saphenous vein insufficiency.
