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Does Treating Varicose Veins Lower Your Clot Risk?

Writer: Dr. Soroush Sohrabi
Dr. Soroush Sohrabi
7d
6 min read

Possibly, but it is not proven. Health-record studies from Taiwan and the United States find fewer deep vein thromboses (DVT) in people whose varicose veins were treated, but we found no randomised trial that has tested this over the long term. The short-term risk from the procedure itself is well measured: after vein ablation, DVT follows in about 3 in 1,000.

For why varicose veins are linked with clots in the first place, see what large studies show about varicose veins, clots and the heart.

The Clot Risk Around a Procedure: Measured Rates

How often does a clot follow treatment? The figures are most thoroughly studied for heat ablation of the great saphenous vein, by laser or radiofrequency. A 2018 systematic review in the European Journal of Vascular and Endovascular Surgery pooled 52 studies and 16,398 patients, all scanned within 30 days:

  • DVT: 0.3 per cent, about 3 in 1,000.

  • Pulmonary embolism: 0.1 per cent, about 1 in 1,000.

  • Heat-induced clot reaching the deep vein: 1.4 per cent.

Endovenous heat-induced thrombosis is a clot extending from the treated vein towards the deep vein. Most are found only because a scan looks for them, and a 2021 update of 75 studies found they usually run a benign course.

English hospital records for 2006 to 2007 put a DVT or pulmonary embolism within 12 months at 0.51 per cent across all varicose vein procedures, and 0.19 per cent after sclerotherapy.

Who Is More Likely to Clot After Treatment

A previous DVT stands out most: in a US series of more than 19,000 procedures, 90 per cent of the patients who developed a clot had had one before. Thrombophilia, an inherited or acquired tendency of the blood to clot, is another recognised factor. In a German study of foam sclerotherapy, it was present in 11 of 85 patients who developed a clot, against 3 of 85 who did not.

Higher risk does not rule treatment out. In a French randomised study of 105 people with the commonest inherited thrombophilias, sclerotherapy given with preventive low-molecular-weight heparin or warfarin produced no DVT on ultrasound monitoring. NICE guidance on preventing venous thromboembolism states that preventive anticoagulation is generally not needed for varicose vein surgery when anaesthesia lasts under 90 minutes and the person is at low clot risk. It recommends considering low-molecular-weight heparin for seven days when anaesthesia lasts longer or clot risk outweighs bleeding risk. A recent review of 11 studies (7,359 patients) could not confirm a benefit from giving it routinely. Dr. Sohrabi's practice follows the NICE guidance.

A duplex ultrasound scan one week and one month after treatment checks that the vein has closed and that no clot has reached the deep vein; Dr. Sohrabi scans at both points. The first week matters most: in a Saudi series of 1,230 treated legs, 63 of the 65 heat-induced clots were found in that week, most without symptoms. Pain and swelling in one calf or thigh, or new breathlessness or chest pain, needs urgent assessment; the NHS sets out the warning signs of DVT. Walking, compression and flight timing, important for long-haul travellers, are covered in recovery after varicose vein treatment.

Long-Term Clot Risk: What Is and Is Not Known

Does closing the vein lower your risk for years afterwards? It is plausible: varicose veins are linked with more DVT, and a genetic study suggests the veins cause a small part of it directly.

The evidence has grown, but it is all observational. In Taiwan, 1,323 people treated by heat ablation had about half the rate of later DVT seen in 149,586 untreated people with varicose veins (adjusted hazard ratio 0.49). A 2025 study of 463,313 health records found fewer DVTs (hazard ratio 0.9) and pulmonary emboli (0.6) after vein procedures, though more surface vein clots. In a US study of 23,190 matched patients having a knee replacement, venous clots in the first month were less common after earlier vein surgery (0.76 against 1.05 per cent), though DVT rates alone were similar. A Scottish study of hip replacements pointed the same way.

Two cautions apply. Treated people may be healthier or more active to begin with. And we found no randomised trial that has counted clots for years after treatment; the one we found, comparing early surgery with stockings or anticoagulants in 562 people with a surface clot, ran for six months and found no difference in DVT at three months.

Repeated surface clots are a separate case. In a Greek study of 97 people with varicose veins followed for about four and a half years after a surface clot, all 13 who had another carried a thrombophilia defect; the authors suggested vein treatment in the longer term for selected patients. After repeated surface clots, Dr. Sohrabi treats the source vein once the inflammation has settled. Treatment does not remove other triggers such as surgery, immobility, pregnancy, hormones or cancer; the common triggers of a DVT are covered separately.

So the reasons to treat remain those in NICE's referral criteria: troublesome symptoms, skin changes, leg ulcers and surface vein clots. A lower clot risk is not yet a reason on its own. Varicose veins treatment explains the options; varicose veins and heart failure takes up the separate question of the heart.

Dr. Soroush Sohrabi is a UK-trained Consultant Vascular and Endovascular Surgeon (FRCS, CCT) practising in Dubai, with a Cleveland Clinic Advanced Endovascular Fellowship and 77 peer-reviewed publications.

Choosing a Surgeon When Clot Risk Matters

Look for a surgeon who assesses your clot risk before treatment and scans the deep veins as well as the surface ones. Dr. Sohrabi holds the FRCS in Vascular Surgery and a CCT, performs and interprets his own duplex scans, and offers thermal and non-thermal closure, foam sclerotherapy and surgery, so the plan follows your anatomy rather than one technique. Book a consultation to discuss your veins and your clot risk.

About the Author

Dr. Soroush Sohrabi MD, PhD, FRCS, CCT (UK), PGCert, MCPhleb is a Consultant Vascular and Endovascular Surgeon practising in Dubai. He trained in the United Kingdom and holds a Fellowship of the Royal College of Surgeons (FRCS) in Vascular Surgery and a Certificate of Completion of Training (CCT). He has published 77 peer-reviewed papers with over 1,183 academic citations and is a member of the European Society for Vascular Surgery (ESVS) and the Vascular Society of Great Britain and Ireland (VSGBI). He is licensed by the UK General Medical Council (GMC No. 5207627) and the Dubai Health Authority (DHA No. 48905551).

Medically reviewed by Dr. Soroush Sohrabi MD, PhD, FRCS, CCT, Consultant Vascular and Endovascular Surgeon, October 2026.

References

  1. Healy DA, Kimura S, Power D, et al. A systematic review and meta-analysis of thrombotic events following endovenous thermal ablation of the great saphenous vein. European Journal of Vascular and Endovascular Surgery. 2018;56(3):410-424. https://doi.org/10.1016/j.ejvs.2018.05.008

  2. Healy DA, Twyford M, Moloney T, Kavanagh EG. Systematic review on the incidence and management of endovenous heat-induced thrombosis following endovenous thermal ablation of the great saphenous vein. Journal of Vascular Surgery: Venous and Lymphatic Disorders. 2021;9(5):1312-1320. https://doi.org/10.1016/j.jvsv.2021.02.006

  3. Sutton PA, El-Dhuwaib Y, Dyer J, Guy AJ. The incidence of post operative venous thromboembolism in patients undergoing varicose vein surgery recorded in Hospital Episode Statistics. Annals of the Royal College of Surgeons of England. 2012;94(7):481-483. https://doi.org/10.1308/003588412X13171221592096

  4. Thakur S, Kaur K, Agarwal S, et al. Retrospective chart review of venous thromboembolism incidence and management in rural patients undergoing varicose vein treatment. Phlebology. 2025;40(6):431-440. https://doi.org/10.1177/02683555241313272

  5. Danneil O, Dörler M, Stockfleth E, Stücker M. Factors influencing superficial and deep vein thrombosis after foam sclerotherapy in varicose veins. Journal der Deutschen Dermatologischen Gesellschaft. 2022;20(7):929-938. https://doi.org/10.1111/ddg.14748

  6. Hamel-Desnos CM, Gillet JL, Desnos PR, Allaert FA. Sclerotherapy of varicose veins in patients with documented thrombophilia: a prospective controlled randomized study of 105 cases. Phlebology. 2009;24(4):176-182. https://doi.org/10.1258/phleb.2009.008081

  7. National Institute for Health and Care Excellence. Venous thromboembolism in over 16s: reducing the risk of hospital-acquired deep vein thrombosis or pulmonary embolism. NICE guideline NG89, Recommendations 1.15.8 to 1.15.11. https://www.nice.org.uk/guidance/ng89/chapter/Recommendations

  8. Ye S, Chen J, Ju J, Yang L. Venous thrombosis prophylaxis after endovenous and open surgery for varicose veins: a systematic review and network meta-analysis. Vascular and Endovascular Surgery. 2026;60(4):348-357 (published online December 2025). https://doi.org/10.1177/15385744251410004

  9. AlGhofili HH, Aljasser AA, Alyahya IA, et al. Endothermal heat-induced thrombosis after endovenous laser ablation: a single-center experience. Seminars in Vascular Surgery. 2019;32(3-4):89-93. https://doi.org/10.1053/j.semvascsurg.2019.06.001

  10. NHS. Deep vein thrombosis (DVT). https://www.nhs.uk/conditions/deep-vein-thrombosis-dvt/

  11. Chang SL, Huang YL, Lee MC, et al. Association of varicose veins with incident venous thromboembolism and peripheral artery disease. JAMA. 2018;319(8):807-817. https://doi.org/10.1001/jama.2018.0246

  12. Li R, Chen Z, Gui L, et al. Varicose veins and risk of venous thromboembolic diseases: a two-sample-based Mendelian randomization study. Frontiers in Cardiovascular Medicine. 2022;9:849027. https://doi.org/10.3389/fcvm.2022.849027

  13. Chang SL, Hu S, Huang YL, et al. Treatment of varicose veins affects the incidences of venous thromboembolism and peripheral artery disease. Circulation: Cardiovascular Interventions. 2021;14(3):e010207. https://doi.org/10.1161/CIRCINTERVENTIONS.120.010207

  14. Moderegger EL, Dräger S, Preuss SL, et al. Increased risk of deep vein thrombosis, pulmonary embolism, and all-cause mortality in chronic venous disorder: a large-scale retrospective cohort study. Frontiers in Medicine. 2025;12:1683970. https://doi.org/10.3389/fmed.2025.1683970

  15. McConnell MJ, Ross BJ, Murphy J, Guild GN, Naylor BH, Bradbury TL. Does surgical treatment of varicose veins prior to total knee arthroplasty decrease rates of postoperative venous thromboembolism? A matched cohort study. Journal of Orthopaedics. 2025;64:169-175. https://doi.org/10.1016/j.jor.2025.04.006

  16. Dua A, Neiva S, Sutherland A. Does previous varicose vein surgery alter deep vein thrombosis risk after lower limb arthroplasty? Orthopaedic Surgery. 2012;4(4):222-226. https://doi.org/10.1111/os.12003

  17. Belcaro G, Nicolaides AN, Errichi BM, et al. Superficial thrombophlebitis of the legs: a randomized, controlled, follow-up study. Angiology. 1999;50(7):523-529. https://doi.org/10.1177/000331979905000701

  18. Karathanos C, Spanos K, Saleptsis V, Tsezou A, Kyriakou D, Giannoukas AD. Recurrence of superficial vein thrombosis in patients with varicose veins. Phlebology. 2016;31(7):489-495. https://doi.org/10.1177/0268355515596475

  19. National Institute for Health and Care Excellence. Varicose veins: diagnosis and management. NICE guideline CG168. https://www.nice.org.uk/guidance/cg168/chapter/Recommendations

 
 
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