DVT Flashcards
What does venous thromboembolism mean?
Blood clot that originates in the vein and includes deep vein thrombosis and pulmonary embolism
Pathogenesis of VTE
Virchow’s triad
1. Venous stasis
2. Endothelial injury
3. Hypercoagulability (hereditary or acquired)
Clinical features of DVT
- Unilateral leg swelling, pain or warmth
- Dilated superficial collateral veins
- Tenderness of deep venous system
- Homan’s sign (pain in the posterior calf or knee with forced dorsiflexion of the foot)
- Phlegmasia cerulea dolens
Types of DVT
- Proximal DVT (iliac, femoral, popliteal) (80%)
- Distal DVT (ant + post tibial, peroneal) (20%)
Differential diagnosis for DVT (unilateral leg swelling)
- Cellulitis
- Ruptured baker’s cyst
- Superficial thrombophlebitis
- Muscle tear/hematoma/sprain/fracture
- Lymphedema
- Chronic venous insufficiency
What score to use for DVT?
Well’s score
Clinical features of well’s score
ABCCDE PPP
+1:
Active cancer
Bedridden recently for >3 days or major surgery within 12 weeks
Calf swelling >3 cm compared to other leg
Collateral superficial veins present
Entire leg swollen
Localised tenderness along the deep venous system
Pitting edema, confined to symptomatic leg
Paralysis, paresis or recent plaster immobilisation of the lower extremity
Previous DVT
-2:
Alternative diagnosis to DT as likely or more likely
How to interpret findings from well’s score and how does it guide next steps?
<2: low/moderate probability of DVT
- proceed to do D-dimer test
2 or more: high probability of DVT
- proceed to do venous compression ultrasound
If D-dimer < 500ng/ml means
DVT is excluded
If D-dimer > 500ng/ml, what is the next step
Venous compression ultrasound
Ultrasound features of DVT
Non-compressible deep vein
Direct visualisation of the thrombus
Positive findings in venous compression ultrasound suggests
DVT confirm, start therapy
Indications to start anticoagulation
Anticoagulation is indicated when the clots are:
- Acute proximal DVT (popliteal, femoral, iliac vein)
- Distal and symptomatic
- Upper extremities and symptomatic
Options of anticoagulants to start
- LMWH (SC clexane) bridged to oral warfarin
- LMWH (SC clexane) for 5 days first followed by direct thrombin inhibitor (dabigatran) - not preferred choice
- DOAC (factor 10a inhibitor - rivaroxaban)
Duration for anticoagulation lasts for
At least 3 months
*choice and duration of anticoagulants depend on doctor and patient factors
Disposition of DVT patients
Admission
Outpatient home treatment for patients with uncomplicated DVT, hemodynamically stable, low bleeding risks
When to treat patients with thrombolytic therapy?
Adjunct to anticoagulation in:
1. Severe or limb threatening DVT
2. Acute proximal DVT with high thrombus burden in young patients with few medical comorbidities and long expected life expectancy
What thrombolytic treatment modalities can be considered?
Catheter directed thrombolysis
Percutaneous mechanical thrombectomy
For patients who are contraindicated to anticoagulation, what treatment option is available?
IVC filter
*also indicated for recurrent DVT/PE despite therapeutic anticoagulation
Complications of untreated DVT
Acute:
- Pulmonary embolism
- Phlegmasia alba dolens
- Phlegmasia cerulea dolens
Chronic:
- Post thrombotic syndrome
- Chronic venous insufficiency
Superior vena cava syndrome
Obstruction of blood flow in superior vena cava either from invasion or external compression of SVC
Causes of SVC syndrome
- Malignancy (lung cancer, lymphoma) - most common
- Thoracic aortic aneurysms
- Iatrogenic causing thrombosis
- Indwelling central venous device
- Dialysis access
- Pacemaker leads
Clinical symptoms of SVC syndrome
- Dyspnea
- Facial swelling, especially when bending forward or in supine
- Upper limb swelling
- Neurological sx (headache, giddiness)
- Chest pain
Clinical signs of SVC syndrome
- Facial edema or plethora
- Venous distension of neck, chest wall and upper limbs especially when patient raises upper limbs
= Pemberton’s manoeuvre (exacerbates obstructive symptoms by decreasing thoracic inlet area) - Cyanosis
- Horner’s syndrome
Immediate investigation in the ED
CXR
- look for external compression
- Mediastinal widening
- Pleural effusion
Management of SVC syndrome
- Manage in P1
- High flow oxygen in upright position
- ETT + mechanical ventilation if patient develops airway compromise
- Consider IV dexamethasone
- Escalate to vascular surgeons for endovenous intervention
- Treat underlying cause (usually secondary to malignancy)
