Teaching resource for medical students.

1. Venous thromboembolism

2. Venous thromboembolism
a leading cause of morbidity & mortality

3. Venous thromboembolism
a leading cause of morbidity & mortality

4. Venous thromboembolism
a leading cause of morbidity & mortality

5. Venous thromboembolism
a leading cause of morbidity & mortality

6. 55-year-old in A&E with a swollen leg.
The doctor says he thinks you have a blood clot.
What do you want to know?

7. Why? What is it?
Is it common?
Genetic?
Is it serious?
Smoking?
Does it run in families?
Old age?
How do you test for it?
Recent flight?
The pill?
Other risk factors?
DVT What now?
What will happen to it?
What’s the treatment?
How long do I have treatment?
What happens when I stop treatment?

8. Natural History of DVT
“About 1 in 1000”
Rare under 16 years
Annual incidence 30/100,000 aged 40
Annual incidence 90/100,000 aged 60
Annual incidence 260/100,000 aged 80

9. Natural History of DVT

10. Natural History of DVT
>80% of symptomatic DVT are
proximal (“above knee”)
PE usually arises from above-
knee DVT
If untreated, 50% of above-knee
DVT lead to PE and <1% of
below-knee DVT
20% of isolated below-knee DVT
will spread proximally

11. Natural History of DVT

12. Natural History of PE

13. Natural History of PE
10% are fatal
(of symptomatic PE)
30% will have a
fatal recurrence
(of untreated non-fatal
symptomatic PE)

15. Altered flow
(venous stasis)
Virchow’s Triad
(end
Alte
red ula tion
othe vess coag ity)
lial el
lte red gulabil
dam A coa
age)
(hy per

16. Risk factors for DVT/PE

17. Risk factors for DVT/PE
Age Malignancy
Previous DVT/PE OCP / HRT
Obesity Pregnancy and postpartum
Immobility Trauma
Hospitalisation Family history
Surgery Inherited thrombophilias

19. Inherited Associated with SLE and autoimmune disease
Recurrent miscarriage or VTE
Presence of an “antiphospholipid” autoantibody
Thrombophilias
The most common (5-8% of some populations)
Clotting factor Va with resistant to cleavage by APC
Antiphospholipid syndrome RR x3-5 for 1st VTE, not significant for recurrent VTE
Factor V Leiden Leads to increased levels of prothrombin (II)
Prothrombin gene mutation Rare (0.7-4%, esp S Europe); RR x2-3 for VTE
Antithrombin deficiency
Rarer; anticoagulant factor deficiencies
Protein C Deficiency RR x5-8 for 1st VTE
Protein S Deficiency

20. Inherited Associated with SLE and autoimmune disease
Recurrent miscarriage or VTE
Presence of an “antiphospholipid” autoantibody
Thrombophilias
The most common (5-8% of some populations)
Clotting factor Va with resistant to cleavage by APC
Antiphospholipid syndrome RR x3-5 for 1st VTE, not significant for recurrent VTE
Factor V Leiden Leads to increased levels of prothrombin (II)
Prothrombin gene mutation Rare (0.7-4%, esp S Europe); RR x2-3 for VTE
Antithrombin deficiency
Rarer; anticoagulant factor deficiencies
Protein C Deficiency RR x5-8 for 1st VTE
Protein S Deficiency
“Thrombophilia Screen”
Antiphospholipid antibodies
COMMON Anticardiolipin antibodies
Lupus anticoagulant
MISCEPTION!
Out of the patients with DVT/PE, Anti-Beta2 glycoprotein I Ab
having an inherited thrombophilia PCR for Factor V Leiden
probably doesn’t increase risk of PCR for Prothrombin gene G20210A variant
recurrent DVT/PE so don’t “just do” a +/- ↓ATIII / ↓Prot C / ↓Prot S
thrombophilia screen!
↑Homocysteine
Malignancy screen

21. Diagnosis of DVT/PE
Three principles

22. 1
It’s often something else
DVT PE
Red painful swollen leg Pleuritic chest pain + SOB
Cellulitis Pneumonia
Thrombophlebitis Chest infection
Ruptured Baker’s cyst Musculoskeletal
Lymphoedema Pneumothorax
Chronic venous insufficiency COPD
Muscle strain/tear IHD + heart failure

23. 2
A gold-standard diagnostic test
which we don’t use clinically any more
DVT PE
Contrast venography Pulmonary angiography
INVASIVE
IMPRACTICAL

24. 3
Clinical risk scoring
before rational further investigation
DVT PE
Well’s Score +/- D-dimer Well’s Score +/- D-dimer
If low score ➝ D-dimer, then If low score ➝ D-dimer, then
if D-dimer neg ➝ excludes DVT if D-dimer neg ➝ excludes PE
Otherwise: Otherwise:
Compression ultrasonography V/Q scan or CTPA
NB inpatients often have raised D-dimers only if CXR normal no worse than V/Q
and are at risk of DVT so proceed straight to USS cheaper but often inconclusive sensitivity 90%

25. vein
artery vein vein non-compressible
PATIENT A – FEMORAL VEIN THROMBUS
artery vein vein compressible
PATIENT B – NO FEMORAL VEIN THROMBUS
Compression ultrasonography

26. No mismatch
= very low
probability result
Ventilation-
perfusion
mismatch
= high probability
V/Q scan

27. CTPA
Spiral (helical) CT with contrast
Thrombus can be seen where the white contrast is missing

28. Treatment
Unprovoked proximal DVT
~8% per year recurrence
+ 50% progress to PE
(if untreated)
Warfarin anticoagulation
3 – 6 months
Nearer 6 months if unprovoked
Lifelong if recurrent