QuestionSBA
QuestionChoice
This patient presents with a typical history of deep vein thrombosis (DVT): a red, hot, swollen calf in the presence of risk factors for venous thrombosis (in this case, long haul flight). The next thing to do in the evaluation of this patient would be a Wells' 2-level DVT score. This patient's Wells' score is 3 points, scoring for: calf swelling >3cm, localised tenderness along the deep venous system and pitting oedema confined to the symptomatic leg. A Wells' score of ≥2 means the patient should have a doppler ultrasound scan of the entire leg to identify any thrombi or emboli in the venous system to confirm the diagnosis. As this patient has a Wells' score of 3, this should be the first investigation
33668
a
Proximal leg vein ultrasound scan
QuestionChoice
Echocardiograms can be used to look for right heart strain associated with a pulmonary embolism, especially in massive pulmonary embolism. However, this patient does not have any signs of pulmonary embolism, so does not need an echocardiogram
33672
e
Echocardiogram
QuestionChoice
V/Q scan is used to diagnose PE in patients with symptoms of PE who are unable to have a CTPA. This patient has no features of PE
33671
d
V/Q scan
QuestionChoice
This patient presents with a history typical of deep vein thrombosis, and their Wells' score is 3. In patients with a Wells' score of ≥2, a doppler ultrasound should be performed first line. If their Wells' score was ≤1, then a d-dimer should be performed. D-dimer has a high sensitivity but low specificity for DVT. This makes it a good rule-out test, but it cannot confirm a DVT. A raised d-dimer can have many causes, including malignancy, infection, pregnancy and stroke
33669
b
D-dimer test
QuestionChoice
Deep vein thrombosis (DVT) is associated with pulmonary embolism, as the original clot in the leg can embolise and travel through the systemic vasculature, through the heart and into the pulmonary arteries. However, there are no features suggestive of pulmonary embolism in this case, including no history of breathlessness, chest pain or haemoptysis. A percentage of patients with DVT will have a silent PE, but asymptomatic patients should not receive a CT pulmonary angiography scan to diagnose a silent pulmonary embolism
33670
c
CT pulmonary angiography
Concept
Chapter
# Summary

Deep Vein Thrombosis (DVT) refers to intra-luminal occlusion of a deep vein with a blood clot, obstructing blood flow. Commonly these occur in the legs although other veins may be affected. DVTs are categorised as "provoked" if a transient risk factor such as pregnancy or surgery is identifiable, and "unprovoked" if not. Key signs and symptoms include leg pain, unilateral erythema, warmth and swelling and distention of superficial veins. The Wells score is commonly used to assess how likely a DVT is based on clinical findings and risk factors; this guides whether a D-dimer blood test or a Doppler ultrasound should be offered first-line. Management is usually with anticoagulation; in rare cases other strategies such as mechanical thrombectomy and IVC filters may be required.
 
# Definition
 
A deep vein thrombosis (DVT) is a blood clot or thrombus that blocks a deep vein, commonly in the legs or pelvis. 
 
# Epidemiology
 
- Venous thromboembolism (which includes both DVT and pulmonary embolism) is common, affecting 1-2 per 1000 people per year
- Two-thirds of cases are DVTs and one-third are pulmonary emboli (PE), with DVT being the main risk factor for PE
- It is particularly common in unwell patients in hospital, with an incidence of up to 37% in critically ill patients

# Aetiology
 
Risk factors for DVT can be remembered with the mnemonic **THROMBOSIS:**
 

 * **T**hrombophilia
 * **H**ormonal (COCP, pregnancy and the postpartum period, HRT)
 * **R**elatives (family history of VTE)
 * **O**lder age (>60)
 * **M**alignancy
 * **B**one fractures
 * **O**besity
 * **S**moking
 * **I**mmobilisation (long-distance travel, recent surgery or trauma)
 * **S**ickness (e.g. acute infection, dehydration)

# Signs and Symptoms
 
- Unilateral erythema, warmth, swelling and pain in the affected area
- Pain on palpation of deep veins
- Distention of superficial veins
- Difference in calf circumference if the leg is affected
 - This should be measured 10cm below the tibial tuberosity
 - > 3cm difference between the legs is significant

# Differential Diagnosis

- **Cellulitis** also causes erythema, warmth, swelling and pain and often affects the legs, patients may have other signs of infection e.g. fevers and there may be an obvious wound or discharge
- **Calf muscle tear** also causes swelling, erythema and pain; there will usually be a history of trauma immediately preceding the development of symptoms
- **Superficial thrombophlebitis** often occurs in the lower limbs in association with varicose veins, however pain is localised to a thrombosed vein rather than there being generalised pain and swelling of the limb
- **Compartment syndrome** can be differentiated by severe pain out of proportion to clinical signs, often preceded by traumatic injury

# Investigations
 
The two-level DVT Wells score is used to risk-stratify patients into patients likely or unlikely to have a DVT as follows:

**Add one point** for each of:

- Active cancer (treatment 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
- Localised tenderness along the distribution of the deep venous system
- Entire leg is swollen.
- Calf swelling at least 3 cm larger than asymptomatic side
- Pitting oedema confined to the symptomatic leg
- Collateral superficial veins
- Personal history of DVT

**Minus 2 points** if an alternative cause is considered at least as likely as a DVT.

If the score is **2 or more**:
 
- DVT is **likely** and an ultrasound doppler of the proximal leg veins should be done within 4 hours
- If this isn't possible within 4 hours, do a D-dimer test, start interim anticoagulation and arrange the doppler to happen within 24 hours
 
If the score is **1 or less**:
 
- DVT is **unlikely** and a D-dimer should be sent
- If the results cannot be obtained within 4 hours, offer interim anticoagulation whilst awaiting results
- If the D-dimer is positive, do an ultrasound doppler of the proximal leg veins 
- If it is negative, anticoagulation should be stopped if it was started and an alternative diagnosis considered

[lightgallery] 

D-dimer is not a specific test and is often raised in infection, trauma, malignancy, post-surgery or haemorrhage. 

Note that separate guidelines exist for pregnant and postpartum women - linked below in references.

**Baseline blood tests** should be taken when anticoagulation is started, including a FBC, U&Es, LFTs and a coagulation screen. 

# Management
 
- First-line anticoagulant medications are **DOACs** (e.g. apixaban, rivaroxaban)
- If these are not suitable, second-line options include low molecular weight heparin (LMWH) for at least 5 days followed by dabigatran or edoxaban, or LMWH bridging with warfarin (with a target INR of 2.5)
- Treatment duration should be at least 3 months for all patients, and 3-6 months for people with active cancer
- At this point the risk of VTE recurrence should be weighed against the risks of continuing anticoagulation to make a decision about whether to continue
- In cases of provoked DVTs (where a major transient risk factor is identifiable e.g. surgery), anticoagulation would usually be stopped at 3 months
- In cases of unprovoked DVTs, consider testing for thrombophilia with antiphospholipid antibodies in patients who are stopping anticoagulation
- Patients with unprovoked DVTs should be reviewed with baseline blood tests and an examination to investigate the possibility of an undiagnosed cancer - further investigations should be guided by the patient's signs or symptoms

[lightgallery1]
 
# Complications

- Pulmonary embolism
- Post-thrombotic syndrome (chronic venous hypertension post-DVT that may cause significant morbidity)
- Complications of anticoagulation e.g. gastrointestinal bleeding

 
# NICE Guidelines
 
[NICE CKS - DVT](https://cks.nice.org.uk/topics/deep-vein-thrombosis/)

[NICE - Venous thromboembolic diseases](https://www.nice.org.uk/guidance/ng158/)
 
# References

[RCEM Learning - Deep Vein Thrombosis](https://www.rcemlearning.co.uk/reference/deep-vein-thrombosis)

[RCOG - Thromboembolic Disease in Pregnancy and the Puerperium](https://www.rcog.org.uk/media/wj2lpco5/gtg-37b-1.pdf)
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Deep Vein Thrombosis (DVT)
Topic
39
Emergency Medicine
6734
A 45-year-old presents to the emergency department with a red, hot and swollen left leg. They have recently travelled back to the UK from Australia. On examination, their pulse is 88/min, and they are apyrexial. Their left lower leg is erythematous to the knee, there is pain on palpation of the leg, pitting oedema, and the left leg is 3.4cm larger than the right.

Which of the following is the next best investigation?
a