QuestionSBA
QuestionChoice
This patient has failed anticoagulation with a direct oral anticoagulant (DOAC). The National Institute for Health Care Excellence (NICE) guidance therefore suggests confirming her adherence to the medication and then either increasing the dosage of the medication or changing for an anticoagulant with a different mode of action. As she is already on the maximum dose of rivaroxaban changing her anticoagulation to warfarin is reasonable
32523
a
Commence warfarin
QuestionChoice
20mg once a day is already the maximum dose for rivaroxaban and therefore a dose increase should only be undertaken in complex cases under the advice of a haematologist. The better option here is to change to a difference mode of anticoagulation
32524
b
Increase her rivaroxaban dose
QuestionChoice
Apixaban is a factor Xa inhibitor, the same as rivaroxaban. This patient has already failed this therapy and therefore an anticoagulant with a different mechanism of action is indicated here
32526
d
Commence apixaban
QuestionChoice
Inferior vena cava filters are only indicated in patients who cannot take blood thinning medications. Changing to a different oral anticoagulant is the preferred option here
32525
c
Insert an inferior vena cava filter
QuestionChoice
Venesection is a recognised treatment for some haematological conditions such as hereditary haemochromatosis and polycythaemia (both of which can increase the risk of DVT) however this woman has been investigated for these conditions previously, therefore this treatment is not indicated
32527
e
Regular venesection
QuestionComment
im not going to memorize the maximum dose for every drug??
7568
User
subscriber
Dermis Cystic
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)
161
Picture
2217
Anticoagulation NICE.png
images/pmtxv4tf1693463348505.jpg
images/pmtxv4tf1693463348505_256.jpg
images/pmtxv4tf1693463348505_512.jpg
89cJHYiph5egiXiIiNd2bc+gxgtq
Picture
2218
DVT NICE.png
images/rk4fdo3x1693463348505.jpg
images/rk4fdo3x1693463348505_256.jpg
images/rk4fdo3x1693463348505_512.jpg
tOcJDYKlh6hqdoevdmeIWLOZT5r4
888
Deep Vein Thrombosis (DVT)
Topic
8
Haematology
Video
Concept
888
Deep Vein Thrombosis (DVT)
88
7tsshSs
images/videos/hematology.png
Deep Vein Thrombosis (DVT) 2
Video
Concept
888
Deep Vein Thrombosis (DVT)
330
1QTvHhh
images/videos/respiratory.png
Quesmed Tutorial: PE and DVT
Video
Concept
888
Deep Vein Thrombosis (DVT)
87
LZ4GpNW
images/videos/hematology.png
Deep Vein Thrombosis (DVT) 1
6505
In patients with recurrent DVT despite optimal DOAC therapy, switching to warfarin may be necessary for effective anticoagulation management.
A 62 year old female has recurrent deep vein thromboses (DVT) for which she takes rivaroxaban 20mg once a day. Unfortunately she develops a new unilateral leg swelling and ultrasound investigation confirms a further deep vein thrombosis. She has been investigated previously for underlying hypercoagulable conditions and all the tests have been negative.

How should you treat this patient?
a