Deep Vein Thrombosis

Presentation with suspected DVT ( Deep vein thrombosis ) is encountered frequently in general practice. This review on A4Medicine is a quick reference on this topic. Using history assessment and the Wells score the GP can decide if the probability is high or low. Quantitative D-dimer testing is not available universally in the primary care across the UK. The aim is to identify DVT, look at the underlying causes and prevent complications.

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

Obesity
Cancer
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
DIC
Snake venom poisoning
 D-dimer can also be elevated in
pregnancy
inflammation
malignancy
trauma
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 
assays
 are available they vary in turnaround times and 
sensitivity and specificity

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

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

Generalization is difficult here – interpretation can be complex D-dimer testing is not universally available in primary care Consequences of untreated DVT can be catastrophic -
if in doubt ring the DVT clinic / MAU for advice 
( worth keeping number of DVT clinic handy ) Management ( anticoagulation treatment ) and f/u of a confirmed DVT is usually via DVT clinic in the UK A few conclusions which can be reached at safely are mentioned below

Imaging- Compression ultrasonography CT MRI Venography ( phlebography )

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

 


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