Vascular
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Question 146 of 180
A 74 year old man presents to the Emergency Department with left calf pain. He had a left total hip replacement 2 weeks earlier, he otherwise has no significant past medical history. On examination he has tenderness and swelling localised to the left calf, it measures 4 cm greater than the right calf. There is no oedema or collateral superficial veins in either leg. What is the patient's Wells score?
Answer:
Use the two-level DVT Wells score to assess the likelihood of DVT and inform further management.- Score one point for each of the following:
- Active cancer (treatment ongoing, within the last 6 months, or palliative).
- Paralysis, paresis, or recent plaster immobilisation of the legs.
- Recently bedridden for 3 days or more, or major surgery within the last 12 weeks requiring general or regional anaesthesia.
- Localised tenderness along the distribution of the deep venous system (such as the back of the calf).
- Entire leg is swollen.
- Calf swelling by more than 3 cm compared with the asymptomatic leg.
- Pitting oedema confined to the symptomatic leg.
- Collateral superficial veins (non-varicose).
- Previously documented DVT.
- Subtract two points if an alternative cause is considered at least as likely as DVT.
- The risk of DVT is likely if the score is two points or more, and unlikely if the score is one point or less.
Deep Vein Thrombosis
Vascular
Last Updated: 24th February 2021
Deep vein thrombosis (DVT) is the term used to describe the 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. The thrombus can dislodge and travel in the blood, especially to the pulmonary arteries. This is known as a pulmonary embolism (PE).
Classification
DVT may be classified as provoked or unprovoked:
- Provoked DVT is DVT associated with a transient risk factor such as significant immobility, surgery, trauma, and pregnancy or puerperium. The combined contraceptive pill and hormone replacement therapy are also considered to be provoking risk factors. These risk factors can be removed, thereby reducing the risk of recurrence.
- Unprovoked DVT is DVT occurring in the absence of a transient risk factor. The person may have no identifiable risk factor or a risk factor that is persistent and not easily correctable (such as active cancer or thrombophilia). Because these risk factors cannot be removed, the person is at an increased risk of recurrence.
Risk factors
Deep vein thrombosis (DVT) is more likely to occur in people with continuing or intrinsic risk factors, such as:
- A history of DVT.
- Cancer (known or undiagnosed).
- Age over 60 years.
- Being overweight or obese.
- Male sex.
- Heart failure.
- Medical illness, for example acute infection.
- Acquired or familial thrombophilia.
- Inflammatory disorders (for example, vasculitis, inflammatory bowel disease).
- Varicose veins.
- Smoking.
Risk factors that temporarily raise the likelihood of DVT include:
- Recent major surgery.
- Recent hospitalisation.
- Recent trauma.
- Chemotherapy.
- Significant immobility (bedbound, unable to walk unaided or likely to spend a substantial portion of the day in bed or in a chair).
- Prolonged travel (for more than 4 hours).
- Significant trauma or direct trauma to a vein (for example intravenous catheter).
- Hormone treatment (for example oestrogen-containing contraception or hormone replacement therapy).
- Pregnancy and the postpartum period.
- Dehydration.
Clinical features
- Consider the possibility of deep vein thrombosis (DVT) if typical symptoms and signs are present, especially if the person has risk factors such as previous venous thromboembolism and immobility.
- Typical signs and symptoms of DVT are:
- Unilateral localised pain (this is usually throbbing in nature) that occurs when walking or bearing weight, and calf swelling (or more rarely, swelling of the entire leg).
- Tenderness.
- Skin changes, which include oedema, redness, and warmth.
- Vein distension.
- Carry out a physical examination and review the person's general medical history to exclude an alternative cause for the symptoms and signs.
- Assess leg and thigh swelling — measure the circumference of the leg 10 cm below the tibial tuberosity and compare with the asymptomatic leg. A difference of more than 3 cm between the extremities increases the probability of DVT.
- Assess for oedema and dilated collateral superficial veins on the affected side.
Differential diagnosis
- Physical trauma, for example:
- Calf muscle tear/Achilles' tendon tear, calf muscle haematoma or fracture
- Cardiovascular disorders, for example:
- Superficial thrombophlebitis, post-thrombotic syndrome, venous obstruction or insufficiency, external compression of major veins (for example by a fetus during pregnancy, or cancer), arteriovenous fistula and congenital vascular abnormalities, acute arterial ischaemia, vasculitis, or heart failure
- Other conditions include:
- Ruptured Baker's cyst, cellulitis, dependent (stasis) oedema, lymphatic obstruction, septic arthritis, cirrhosis, nephrotic syndrome, compartment syndrome
Management
- Use the two-level DVT Wells score to assess the likelihood of DVT and inform further management.
- Score one point for each of the following:
- Active cancer (treatment ongoing, within the last 6 months, or palliative).
- Paralysis, paresis, or recent plaster immobilization of the legs.
- Recently bedridden for 3 days or more, or major surgery within the last 12 weeks requiring general or regional anaesthesia.
- Localised tenderness along the distribution of the deep venous system (such as the back of the calf).
- Entire leg is swollen.
- Calf swelling by more than 3 cm compared with the asymptomatic leg.
- Pitting oedema confined to the symptomatic leg.
- Collateral superficial veins (non-varicose).
- Previously documented DVT.
- Subtract two points if an alternative cause is considered at least as likely as DVT.
- The risk of DVT is likely if the score is two points or more, and unlikely if the score is one point or less.
- Score one point for each of the following:
- For people who are likely to have DVT (based on the results of the two-level DVT Wells score):
- Offer a proximal leg vein ultrasound scan with the results available within 4 hours if possible.
- If a proximal leg vein ultrasound scan cannot be carried out within 4 hours of being requested, offer:
- A D-dimer test, then
- Interim therapeutic anticoagulation (if possible, choose an anticoagulant that can be continued if DVT is confirmed) and
- A proximal leg vein ultrasound scan with the results available within 24 hours.
- For people who are unlikely to have DVT (based on the results of the two-level DVT Wells score):
- Offer a D-dimer test with the results available within 4 hours. If the results cannot be obtained within 4 hours offer interim therapeutic anticoagulation while awaiting the result (if possible, choose an anticoagulant that can be continued if DVT is confirmed).
- If the D-dimer test is positive, offer a proximal leg vein ultrasound scan with the results available within 4 hours if possible. If the results cannot be obtained within 4 hours offer interim therapeutic anticoagulation and a proximal leg vein ultrasound scan with the result available within 24 hours.
- If the D-dimer test is negative:
- Stop interim therapeutic anticoagulation.
- Consider an alternative diagnosis.
- Tell the person that it is likely they do not have DVT, discuss the signs and symptoms of DVT, and when and where to seek further medical help.
- If interim therapeutic anticoagulation is required:
- Offer apixaban or rivaroxaban first line, and if these are not suitable, low molecular weight heparin (LMWH) for at least 5 days followed by dabigatran or edoxaban, or LMWH concurrently with a vitamin K antagonist for at least 5 days.
- Take into account comorbidities, contraindications, and the person's preferences when choosing anticoagulation treatment.
- Carry out baseline blood tests including full blood count, renal and hepatic function, prothrombin time (PT), and activated partial thromboplastin time (APTT). Do not wait for the results of baseline blood tests before starting anticoagulation treatment.
- Follow-up of person with confirmed DVT:
- Provided there are no contraindications (such as pregnancy or cancer), people who have been diagnosed with deep vein thrombosis (DVT) will require maintenance treatment with an oral anticoagulant (warfarin, apixaban, dabigatran, edoxaban, or rivaroxaban) following acute treatment.
- Specialists will make clinical decisions such as the choice of anticoagulant and the duration of treatment. Treatment is usually continued for at least 3 months, but duration may be longer depending on whether the DVT was unprovoked (no obvious, transient risk factor identified) or provoked (caused by an identifiable, transient, major risk factor).
- Ensure that people with unprovoked DVT are investigated for the possibility of an undiagnosed cancer if they are not already known to have cancer and that they have been offered thrombophilia testing, as appropriate.
Complications
- The most serious complication of deep vein thrombosis (DVT) is death due to pulmonary embolism (PE).
- Other complications of DVT include:
- Post-thrombotic syndrome — a chronic venous hypertension causing limb pain, swelling, hyperpigmentation, dermatitis, ulcers, venous gangrene, and lipodermatosclerosis.
- Bleeding associated with anticoagulation treatment — most episodes are associated with a previously unknown pathological lesion (for example, duodenal ulcer).
- Heparin-induced thrombocytopenia (HIT) — this may occur 5–7 days after initial exposure to heparin, but can occur in less than 1 day in people previously exposed to heparin. The incidence is low in people treated with low molecular weight heparin (for example, dalteparin, enoxaparin, tinzaparin). Fondaparinux-associated HIT is rare.
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
