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Deep Vein Thrombosis ( DVT )

VTE ( Venous thromboembolism ) is a condition in which blood clot
 ( thrombus ) forms in a vein. It most commonly occurs in the deep veins of the legs – called DVT. The thrombus may dislodge from its site of origin to travel in the blood – called embolism ( NICE 2010 )

VTE is a multicausal disease , the result of coincidence of several risk factors- as-Inherent to the
 individual and may be inherited – eg

 thrombophilia .Inherent to the individual and can be acquired eg

Certain drugs
 Result of an inter-current illness or procedure , or other cause of temporary reduced mobility eg

 following major trauma or surgery , serious medical disorder , pregnancy or long-haul travel

Risk factors- Age > 60 yrs Obesity 2 to 3 fold increase if BMI > 30 kg/m2 Varicose veins 1.5 to 2.5 fold risk after major general/ ortho surgery Family h/o VTE Thrombophilias Other thrombotic states cancer heart failure recent MI/ stroke metabolic syndrome severe acute infection chronic HIV infection inflammatory bowel disease nephrotic syndrome myeloproliferative disease paraproteinaemia Bechet’s disease paroxysmal nocturnal haemoglobinuria sickle cell trait and sickle cell disease .Combined oral contraceptive Oral oestrogen HRT Raloxifene and tamoxifen Pregnancy Puerperium Immobility Immobility during travel Hospitalisation Anaesthesia Central venous catheters

Recurrent FVT risk factors-Previous unprovoked VTE Male sex Obesity Thrombophilias

Virchow’s triad- Venous stasis Alteration in blood constituents Changes in endothelium

Presentation-Edema Leg pain Tenderness Warmth or erythema of the skin over the area of thrombosis Calf pain on dorsiflexion of foot Palpable indurated cordlike tender s/c venous segment Variable discoloration of the lower extremity Reduced mobility-These clinical signs are not specific for DVT- clinical scoring systems and diagnostic tests have been developed

Scoring-Two-level DVT Wells Score (Wells PS et al 2003 )

D-dimer-D-dimer is the degradation product of crosslinked ( by factors XIII ) fibrin – it reflects ongoing activation of the hemostatic system

can help in the following situations

Evaluation of thrombus formation
Ruling out DVT
Monitoring anticoagulative treatment
Snake venom poisoning
 D-dimer can also be elevated in
postsurgical treatment
liver disease
 A negative D-dimer test is good enough to exclude the diagnosis of DVT in people with an unlikely pre-test clinical probability , but is not good enough to exclude the diagnosis of DVT in those with a likely pre-test probablity Good sensitivity ( 95 % for DVT ) but poor specificity ie a negative test can r/o VTE but positive result is not specific for VTE.Various D-dimer 
 are available they vary in turnaround times and 
sensitivity and specificity

 D-dimer levels correlate
 with the size of the 
thrombus and clot

Differential diagnosis- Cellulitis Calf muscle tear / achille tendon tear Calf muscle haematoma Ruptured Baker’s cyst Superficial thrombophlebitis Venous obstruction or insufficiency

Complications- Pulmonary embolism Post-thrombotic syndrome
chronic venous hypertension causing limb pain , swelling , hyperpigmentation , dermatitis , ulcers , venous gangrene and lipodermatosclerosis
can affect 20-40 % people after DVT Venous ulcers

Alternative diagnosis –An unlikely two-level DVT Wells score and
 a negative D-dimer test OR a positive D-dimer test and a negative proximal leg vein US

A likely two-level DVT Wells score and
 a negative proximal leg vein US and a negative D-dimer test OR a repeat negative proximal leg vein US

Advise patients from these two groups that it is not likely that they have DVT and discuss with then signs and symptoms of DVT ( see PILs under links and resources ) and when and where to seek further medical advice ( NICE guideline )

The annual incidence of VTE ( DVT & PE ) in high-income countries is approximately 70-270 per 100 000 people Diagnosing VTE is challenging as symptoms may be non-specific and the clinical presentation can vary significantly If the patient is pregnant discuss directly with the obstetric team If the patient is seen in OOH setting or an admission is not feasible ( e.g patient declines /transport ) you may consider giving a dose of anticoagulant and arranging an appointment in DVT clinic the following day .

It is important to get a venous blood sample for D-dimer before staring anticoagulant as D-dimer cannot be used as part of the diagnostic algorithm once patients have received a dose of an anticoagulant

The following agents can be used- issues short supply to cover till the patient gets seen in the DVT clinic



NHS page on DVT a concise useful section with an image

A collection of very useful printable booklets from Thrombosis UK Org – excellent work

Chest Foundation on DVT -a comprehensive page

Apixaban -information for patients in multiple languages

Clotconnect Org has some excellent booklets for patient on all matters related to VTE/ anticoagulation ( DVT booklet is 28 pages )

Circulation Foundation on DVT ( video does not work )


American Society of Haematology – an excellent page for education and patient information with videos and printable leaflets

Venous Thromboembolic disease: diagnosis and management  NICE guideline

SIGN guideline Prevention and management of venous thromboembolism

ASH -New Clinical Practice Guideline for VTE

MD Calc Wells criteria




  1. E Medicine Deep Vein Thrombosis ( DVT ) Updated July 2017 Author Kaushal ( Kevin ) Patel MD et al
  2. Venous thromboembolic disease : diagnosis management and thrombophilia testing NICE  Clinical guideline ( CG 144 ) Published : June 2012 Last updated : November 2015
  3. Deep vein thrombosis Risks and diagnosis Wai Khoon Ho Australian Family Physician Vol 39 , No 7 , July 2010
  4. Venous thromboembolism : reducing the risk for patients in hospital NICEClinical guideline ( CG92 ) January 2010 Last updated June 2015
  5. Diagnosis , investigation , and management of deep vein thrombosis BMJ 2003 ;326 : 1180
  6. Prevention and management of venous thromboembolism SIGN Quick Reference Guide 122 December 2010
  7. BMJ Best Practice Deep Vein Thrombosis
  8. NICE Clinical Knowledge Summaries : Deep Vein Thrombosis April 2013
  9. Thrombosis Canada Deep Vein Thrombosis Diagnosis 2016
  10. Management of deep vein thrombosis and prevention of post-thrombotic syndrome BMJ 2011 ; 343:d5916
  11. Medscape D-dimer Reka G Szigeti MD et al 2014
  12. Oxford Hemophilia and thrombosis Centre Out-Patients DVT Service protocol via
  13. General practitioner use of D-dimer in suspected venous thromboembolism:
    historical cohort study in one geographical region in the Netherlands via



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