DVT Flashcards
What two conditions are included in the term venous thromboembolism?
- DVT
- PE
What is DVT?
Deep vein thrombosis isdevelopment of a blood clot in a major deep vein in the leg, thigh, pelvis, or abdomen, which may result in impaired venous blood flow and consequent leg swelling and pain.
State some risk factors for DVT
- Cancer
- Major surgery in past 3 months
- Immobilisation
- Long haul flights
- Pregnancy
- Trauma
- Smoking
- Coagulopathies e.g. antiphospholipid syndrome
- SLE (some pts also have antiphospholipid syndrome)
- Polycythaemia
- Oral contraceptive use
- Hospitlisation
State signs & symptoms of DVT
May be asymptomatic or the following signs & symptoms may be present unilaterally/in one leg:
- Swelling
- Pain (may worsen on standing & walking)
- Hard on palpation
- Tender on palpation
- Prominent superficial veins
- Red
- Hot to touch
If you want to measure leg to check if it is swollen compared to the other, how should you measure it?
Measure circumference of each leg 10cm below tibial tuberosity
State some differentials for a pt presenting with unilateral leg pain, swelling, redness, warmth and tenderness
- DVT
- Cellulitis
- Large or ruptured Baker’s cyst
- Pelvic/thigh mass or tumour compressing veins
- Calf muscle or Achilles tendon tear
What scoring system do we use to assess the likelihood of DVT?
Well’s score for DVT.
- <2 : DVT unlikely- proceed to D-dimer
- >/=2 : DVT likely- proceed to ultrasound
State what investigations you would do if you suspect DVT, include:
- Bedside
- Bloods
- Imaging
*For each, justify why you are doing it
Bedside
- Calculate Well’s score for DVT
Bloods
- FBC: rule out infection e.g. cellulitis, platelet count can be used to guide anticoagulation
- D dimer: may be raised
- Coagulation studies: need before start anticoagulation
- U&Es: baseline value for treatment
- LFTs: baseline value for treatment
Imaging
- Ultrasound doppler of leg: assess if can fully compress vein, if there are any abnormalities of flow,. All vein segments SHOULD be fully compressible
D dimer test is sensitive (95%) but not specific; what does this mean in terms of what we can infer from results?
Remember:
- Sensitivity: the proportion of people who test positive among all those who actually have the disease. Hence, if a test has high sensitivity and a pts result comes back negative it helps us to rule out that disease.
- Specificity: specificity of a test is the proportion of people who test negative among all those who actually do not have that disease. Hence, if a test has a high specificity and a pts result come back positive it helps us rule in a that disease
Therefore, since D dimer is sensitive this means that if the D dimer is low, AND THERE IS LOW CLINICAL SUSPCION, of DVT; DVT can be ruled out.
D dimer can be raised due to numerous factors; state some causes of raised D-dimer other than DVT
- Pregnancy
- Malignancy
- Heart failure
- Surgery
- Pneumonia
If a pt presents with VTE without a clear cause, what did NICE previously recommend?
NICE PREVIOUSLY recommended you investigate for cancer but this is not recommended anymore; the investigations would have included:
- CXR
- Bloods (FBCs, LFTs, calcium)
- Urine dipstick
- CT abdo & pelvis
- Mammaogram in women over 40yrs
- Antiphospholipid antibodies
Discuss what NICE recommend in the following situations:
- Wells score ≥ 2 hence you arrange leg vein ultrasound but it cannot be done within 4hrs
- Following the above, doppler ultrasound comes back negative but D dimer comes back raised
- Wells score <2 but D-dimer raised
- If cannot do leg vein ultrasound within 4hrs, do a d-dimer and give interim anticoagulation with DOAC whilst waiting for scan (which should be in 24hrs)
- If d-dimer raised but doppler ultrasound of leg veins is negative, NICE reccommends repeating the doppler ultrasound 6-8 days later
- If Wells score <2 but d-dimer comes back raised arrange doppler ultrasound of leg within 4hrs; if cannot be done within 4hrs give interim anticoagulation
Discuss the management of DVT
(SAME AS FOR PE)
Drug Choice
- NICE recommend using a DOAC (apixaban or rivaroxaban) if PE suspected and continue if diagnosis confirmed (in 2020 guidance changed from LMWH initially to being able to use DOACs. Guidance also used to state cancer pts had to have LMWH but can now have DOACs)
- If apixaban or rivaroxaban not suitable, can do either LMWH followed by dabigatran or edoxaban OR LMWH followed by a vitamin K antagonist (warfarin)
- If have antiphospholipid syndrome, must have LMWH followed by vitamin K antagonist
- If severe renal impairment, LMWH may be used (check BNF if low renal function)
Duration of treatment
- If wad provoked → anticoagulate for 3 months then assess
- If was unprovoked→ anticoagulate for 6 months then reassess balancing risk of further thrombosis/emboli with bleeding risk. In reality, most pts with unprovoked VTE are on life long anticoagulation as long as bleeding risk does not outweigh
- Pt has persistent thrombotic risk and/or previous emboli should be anticoagulated for life
- Cancer associated → 6 months then review
What is the target INR in DVT?
2-3
*When switching from LMWH to warfarin you must continue LMWH for 5 days or until INR is between 2-3 for 24 hours- whichever is longer.
What would be your anticoagulant of choice for DVT in:
- Pregnancy
LMWH sc
