DVT Flashcards
Define DVT
Deep vein thrombosis refers to the intra-luminal occlusion of any vein within the deep system of a limb (either arm or leg) or the pelvis.
Epidemiology
Venothromboembolism (which includes both DVT and PE) is thought to affect 1 in 10,000 people under 40 years old each year and 1 in 100 people over 80 years old.
Up to 20% of cancer patients develop VTE.
Risk factors
Age >60
Active cancer
Dehydration
Recent orthopaedic or pelvic surgery
Long-distance travel
Obesity
Previous history of VTE
Family history of VTE
Thrombophilias
Combined oral contraceptives and hormone replacement therapy
Pregnancy
Clinical features
Unilateral warm, swollen calf or thigh
Pain on palpation of deep veins
Distention of superficial veins
Pitting oedema
Well’s score for DVT
predicts the likelihood of a DVT.
Max = 9
Min = -2
Clinical feature - Points
Active cancer (treatment ongoing, within 6 months, or palliative) 1
Paralysis, paresis or recent plaster immobilisation of the lower extremities 1
Recently bedridden for 3 days or more, or major surgery within 12 weeks requiring general or regional anaesthesia 1
Localised tenderness along the distribution of the deep venous system 1
Entire leg swollen 1
Calf swelling at least 3 cm larger than asymptomatic side 1
Pitting oedema confined to the symptomatic leg 1
Collateral superficial veins (non-varicose) 1
Previously documented DVT 1
An alternative diagnosis is at least as likely as DVT -2
2 or more = DVT likely
1 or less = DVT unlikely
Investigations
- D-dimer
- Doppler ultrasound
- Digital subtraction or CT/MR venogram
Investigations: D-dimer
Generally used in situations where there is a low probability of DVT.
Is highly sensitive but not specific which means that it can only reliably exclude VTE and does not confirm it.
Other common conditions which may raise the D-dimer include malignancy, infection, pregnancy, stroke, myocardial infarction and aortic dissection.
Investigations: Doppler US
Typically considered the investigation of choice for diagnosis.
Patients with high probability of DVT will normally have a Doppler ultrasound without the need for a D-dimer first.
Although highly sensitive and specific it is not the gold-standard investigation because DVTs can be missed if image quality is suboptimal.
Investigations: Digital subtraction or CT/MR venogram
All three can be used to evaluate the extent of a DVT and look for rare underlying causes such as May-Thurner syndrome.
Digital subtraction venography is technically the gold-standard investigation but is rarely used due to it’s highly invasive nature.
Management
- Anticoagulation - NICE recommends DOAC e.g. apixaban or rivaroxaban as 1st line
= LMWH and warfarin other alternatives - Percutaneous mechanical thrombectomy
- IVC filter
- Further investigations
Management: Anticoagulation
either a (DOAC), Low Molecular Weight Heparin (LMWH) or warfarin (which can be bridged with LMWH.)
NICE guidelines recommend DOACs such as Apixaban or Rivaroxaban as first line therapy.
- Duration is typically at least 3 months.
- If active cancer or unprovoked DVTs –> at least 3-6 months
- If cancer –> DOAC, not LMWH
- Those with recurrent DVTs should be considered for life-long therapy.
Management: Percutaneous mechanical thrombectomy
Used for massive DVTs
Management: IVC filter
NOT TREATMENT
Used in patients where anticoagulation is contraindicated.
- Reduces the risk of the DVT embolising into the pulmonary arteries causing a PE.
Management: Further investigations
Investigation of occult malignancy should be considered if there are other relevant symptoms.
Thrombophilia screening should be considered if clinically relevant
Complications of DVT
Pulmonary Embolus
Recurrent DVT
Post-thrombotic syndrome - pain, swelling, hyperpigmentation, dermatitis, ulcers, gangrene and lipodermatosclerosis caused by chronic venous hypertension.
