Clinical Notes : Cardiovascular

39. Deep Vein Thrombosis (lower extremities)


  • key diagnostic factors

    • calf swelling

      • measure the circumference of the leg 10 cm below the tibial tuberosity

      • difference in circumference, of >3 cm between the extremitiesmeans DVT is more likely.

    • localised pain along deep venous system

      • palpate along the path of the deep venous system from groin to adductor canal and in the popliteal fossa.

  • other diagnostic factors

    • common

      • asymmetric oedema

        • worse on leg with suspected DVT

      • prominent superficial veins

        • dilated superficial veins over foot and leg (not varicose veins) 

    • uncommon

      • swelling of the entire leg

      • phlegmasia cerulea dolens

        • when DVT is massive, the swelling can obstruct not only venous outflow but arterial inflow, leading to phlegmasia cerulea dolens due to ischaemia

        • the leg is blue and painful.

Risk Factors


  • medical hospitalisation within the past 2 months

    • approximately 20% of all incident venous thromboembolic events (VTEs) develop either during a medical hospitalisation or within 2 months of a hospitalisation of 4 or more days.

  • major surgery within 3 months

    • reasons include postoperative immobilisation, inflammation, underlying comorbidity, and injury to the venous system in selected cases (e.g., total knee replacement)

  • active cancer

    • DVT rates are likely to be 4- to 7.5-fold higher in patients with cancer than in the general population

    • patients with metastatic cancer at the time of diagnosis are at especially increased risk​

  • lower-extremity trauma

    • surgical and non surgical injuries

  • severe trauma

    • vascular injury and release of inflammatory marker

  • pregnancy

    • the relative risk for DVT during pregnancy and the postnatal period is substantially elevated

    • the absolute risk in pregnancy remains low

  • medical comorbidity

    • especially with inflammation, infection, and immobility.

  • use of specific drugs

    • oestrogen-containing oral contraceptives

    • tamoxifen and raloxifen

    • cancer meds

      • thalidomide

      • erythropoietin

  • rare deficiencies

    • factor V Leiden

      • the rare patient who is homozygous for FVL has substantially higher risk of developing VTE compared with heterozygotes

    • prothrombin gene mutation G20210A

      • the rare patient who is homozygous for prothrombin gene mutation have substantially greater risk of developing VTE compared with heterozygotes.

    • protein C or S deficiency

      • 5- to 6-fold greater risk of developing venous thromboembolic events

    • antithrombin deficiency

      • levels unaffected by warfarin

      • levels lower in the presence of therapeutic levels of unfractionated heparin

    • antiphospholipid antibody syndrome

      • the risk of recurrent venous thromboembolic events when off anticoagulation therapy is approximately twice as high


  • obesity

    • body mass index  >30 kg/m²

  • recent long-distance air travel

    • the absolute risk with air travel appears to be small

    • flights longer than about 4 hours are associated with elevated risk

  • family history

    • of DVT or pulmonary embolism increase the risk


use a combination of Wells Score and D-Dimers in OOH service

duplex ultrasound in A+E



  • If Wells score ≥ 2

    • refer to A+E

  • If Wells score ≤ 1, perform D-Dimer test

    • Refer to A+E if D-Dimer test is not available in OOH service

    • Refer to A+E if D-Dimer test +ve

wells score.png

Wells Score



  • LMWH pending USS and, if DVT is confirmed, until INR is >2

  • Oral rivaroxaban (NOAC) is an alternative option to LMWH and warfarin for the treatment of acute DVT

    • If DVT is confirmed, the dose is 15mg bd for 3 weeks, followed by 20mg once daily for subsequent prevention of recurrence

  • Class 2 or 3 below knee graduated compression stockings 1 week after diagnosis when swelling has subsided

    • wear for 2 years

    • should be replaced 2-3 times per year


Rivaroxaban for the treatment of deep vein thrombosis and prevention of recurrent deep vein thrombosis and pulmonary embolism

Technology appraisal guidance TA261. July 2012.



Exclusion of deep vein thrombosis using the Wells rule in clinically important subgroups: individual patient data meta-analysis

BMJ 2014;348:g1340. March 2014.


Venous thromboembolism in over 16s: reducing the risk of hospital-acquireddeep vein thrombosis or pulmonary embolism

NICE guideline [NG89]

March 2018


Prevention and management of venous thromboembolism

SIGN guideline 122

updated October 2018


Diagnosis and management of acute deep vein thrombosis: a joint consensus document from the European Society of Cardiology working groups of aorta and peripheral vascular diseases and pulmonary circulation and right ventricular function

European Heart Journal, Volume 39, Issue 47, 14 December 2018, Pages 4208–4218,


Deep vein thrombosis 

BMJ Best Practice.

November 2018


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