Deep vein thrombosis Flashcards
Define deep vein thrombosis
Formation of a thrombus (blood clot) in a deep vein, which partially or completely obstructs blood flow.
Thrombosis usually affects the deep veins of the legs or pelvis, but may affect other sites such as the upper limbs and the intracranial and splanchnic veins
What does the term VTE mean?
Venous thromboembolism
Any thromboembolic event occurring within the venous system, including DVT and PE
Deep vein thrombosis continuing/instrinsic risk factors
Previous VTE Cancer Age over 60 years Being overweight or obese Male sex Heart failure Severe infection Acquired or familial thrombophilia Chronic low-grade injury to the vascular wall (e.g. vasculitis, hypoxia from venous stasis, or chemotherapy) Varicose veins Smoking
Temporary DVT risk factors
Immobility Significant trauma or direct trauma to a vein COCP or HRT Pregnancy and postpartum Dehydration
Complications of DVT
Death due to PE
Post-thrombotic syndrome — a chronic venous hypertension causing limb pain, swelling, hyperpigmentation, dermatitis, ulcers, venous gangrene, and lipodermatosclerosis
How is a clot formed?
Damage to endothelium –> vasoconstriction –> platelets adhere to damaged vessel wall and become activated by collagen and tissue factor –> platelets form a platelet plug (primary haemostasis) –> coagulation cascade activated –> fibrinogen to fibrin, forming mesh around platelets (secondary haemostasis) –> hard clot at site of injury.
DVT symptoms/signs
Calf swelling - unilateral usually, sometimes get swelling of entire leg (uncommon), pitting oedema
Localised pain along deep venous system (CALF PAIN)
Erythema
Warm to touch
Vein distension
Differentials for DVT
- Physical trauma - calf muscle tear/strain, haematoma, rupture of Achilles tendon, fracture
- Superficial thrombophlebitis
- Post-thrombotic syndrome
- Venous obstruction or insufficiency, or external compression of major veins
- AV fistula and congenital vascular abnormalities
- Acute limb ischaemia
- Vasculitis
- Heart failure
- Ruptured Baker’s cyst
- Cellulitis
- Dependent (stasis) oedema
- Lymphatic obstruction
- Septic arthritis
- Cirrhosis
- Nephrotic syndrome
- Compartment syndrome
DVT Wells score
Score one point for each of the following:
Active cancer
Paralysis, paresis, or recent plaster immobilization of the legs
Recently bedridden for 3 days or more, or major surgery within the last 12 weeks
Localized tenderness along the distribution of the deep venous system
Entire leg is swollen
Calf swelling by more than 3 cm compared with the asymptomatic leg
Pitting oedema
Collateral superficial veins (non-varicose)
Previously documented DVT
Subtract two points if an alternative cause is considered more likely than DVT.
When you suspect DVT, do history and exam and Well’s score. What to do if Well’s score is >= 2?
= likely to have DVT
Refer for a proximal leg vein ultrasound scan to be carried out within 4 hours.
If cannot be carried out within 4 hours, do D-dimer and give interim 24-hour dose of parenteral anticoagulant and do scan within 24 hours
When you suspect DVT, do history and exam and Well’s score. What to do if Well’s score is one or less?
= unlikely to have DVT
Offer D-dimer testing - if positive, refer for proximal leg vein USS scan within 4 hours
If cannot be carried out within 4 hours, give interim 24-hour dose of parenteral anticoagulant and do scan within 24 hours
If D-dimer negative, consider alternative diagnosis
Management of DVT (anticoag)
LMWH or fondaparinux should be given initially for at least 5 days, plus
a vitamin K antagonist (i.e. warfarin) within 24 hours for at least 3 months (6 months if cancer or unprovoked DVT)
What is post-thrombotic syndrome (pathology)?
Venous outflow obstruction and/or destruction of venous valves –> venous insufficiency –> chronic venous hypertension –> painful heavy calves, pruritus, swelling, varicose veins, venous ulceration, hyperpigmentation, dermatitis, venous gangrene, lipodermatosclerosis
Management of post-thrombotic limb
Raising leg
Grade-2 compression stockings
Exercise, weight loss, painkillers, caring for wound if ulcer
Intermittent pneumatic compression (pump to apply external pressure to leg by inflating and deflating plastic boots)
May get referral to vascular surgery
Management of venous ulceration
Compression bandaging, usually four layer = only treatment with strong evidence
Other options:
Oral pentoxifylline (peripheral vasodilator)
Flavinoids
Hydrocolloid dressings, topical growth factors, ultrasound therapy and intermittent pneumatic compression (little evidence)
