Makindo Medical Notes.com

Related Subjects: |Assessing Breathlessness |Respiratory failure |Pulmonary Embolism |Deep Vein Thrombosis |DVT/PE in pregnancy |CTPA

About

• Most pulmonary emboli originate as DVTs in the pelvic or leg veins
• Failure to treat can lead to PE and post thrombosis problems
• Aim to prevent DVT/PE in hospital with early mobilisation, LMWH and/or TED stockings

Risks

• Generalised Immobility e.g. illness, stroke and other neurology
• Post operative, Malignancy
• Pelvic/Orthopaedic/Gynaecological surgery
• Pregnancy and postpartum and COCP
• Factor V Leiden, Protein C deficiency, Protein S deficiency
• Age > 60, Smoking, Obesity
• Recent travel > 4 hrs within 2 weeks
• Congestive cardiac failure, HONK

Risks associated with OCP

• No combined pill: 5 DVT/PE per 100,000
• Second generation combined pill: 15 DVT/PE per 100,000
• Third generation combined pill: 25 DVT/PE per 100,000
• Pregnancy: 60 DVT/PE per 100,000

Clinical

• Calf pain, Dilated veins and erythema
• Homan's sign - pain on dorsiflexion of the foot
• Positive tibial tap. Obvious swelling
• Increase in circumference compared with the other leg

Investigations

• D-Dimer only if low risk of DVT
• Med/High risk get Compression USS is good for proximal thrombi as the vein is found to be non-compressible. May miss below-knee DVTs.
• Venography is done rarely nowadays but is the "gold standard"
• MRI has been used but expensive
• Look for a prothrombotic disorder in some - see thrombophilia screen

Differential

• Venous thrombosis
• Calf haematoma
• Ruptured Baker's cyst
• Cellulitis/Soft tissue infection
• Lymphatic obstruction
• CCF/Cor pulmonale
• Rupture of head of gastrocnemius
• Low albumin

Well's score

• Paralysis, paresis or recent orthopaedic casting of the lower extremity (1 point)
• Recently bedridden (more than 3 days) or major surgery within past 4 weeks (1 point)
• Localized tenderness in deep vein system (1 point)
• Swelling of the entire leg (1 point)
• Calf swelling 3 cm greater than another leg (measured 10 cm below the tibial tuberosity) (1 point)
• Pitting oedema greater in the symptomatic leg (1 point)
• Collateral non varicose superficial veins (1 point)
• Active cancer or cancer treated within 6 months (1 point)
• Alternative diagnosis more likely than DVT (Baker's cyst, cellulitis, muscle damage, superficial venous thrombosis, post-phlebitic syndrome, inguinal lymphadenopathy, external venous compression) (-2 points)

Interpretation

• 3-8 Points: High probability of DVT
• 1-2 Points: Moderate probability
• -2-0 Points:Low Probability

No decision rule should outweigh clinical experience. High suspicion for DVT should warrant imaging regardless of Wells score.

Management

• Most ambulant patients can be managed as an outpatient
• If a DVT is suspected then start weight-adjusted LMWH e.g. Enoxaparin 1 mg/kg bd usually for 5 days
• Once this is confirmed by imaging Warfarin is started at 3-5 mg daily until therapeutic along with LMWH and then dose-adjusted
• Streptokinase has been used to treat large proximal DVT's
• Below knee DVT - 6 weeks Warfarin
• DVT or PE with no obvious cause - 6-12 months Warfarin
• DVT with a one-off cause - 3 months Warfarin
• A further DVT/PE would warrant consideration of lifelong Warfarin.
• Thrombolysis may be considered for a huge iliofemoral DVT with a risk of limb gangrene

References

• Wells PS, Anderson DR, Bormanis J, et. al. Value of assessment of pretest probability of deep-vein thrombosis in clinical management. Lancet. 1997 Dec 20-27;350(9094):1795-8.