Deep Vein Thrombosis

DVTs

Risk Factors

Virchow's triad was first elaborated upon in 1860, and still remains important.

hypercoagulability

stasis (bedriddenness, paralysis, paresis, casting, coma)

endothelial damage (smoking, birth control pill, obesity)

 

Active cancer: perhaps 10-20% of older folks with idiopathic DVT will be found to have an underlying malignancy within a year. Common procoagulant cancers include GI, prostate, ovary, lung, and pancreas.

Other risk factors include:

Genetics can also predispose to venous thrombosis;

 

  • history
  • physical exam
  • Tab 5
  • Tab 6
  • diagnostic algorithms
  • differential diagnosis

History

Evaluate presence/absence of risk factors, as described above.

Symptoms of DVT include pain, immobility, heat, and swelling.

Calf-popliteal DVT: symptoms spread proximally over time (80-90%)

Ileofemoral DVT: pain in buttocks, groin, with subsequent thigh swelling (10-20%).

Family history should be evaluated, especially in younger patients.

Physical Exam

Assess for swelling by measuring at the same point bilaterally - 10 cm below tibial tuberosity.

Warmth and erythema can also be seen. If it is a large PE, colour can be dusky bluish.

Look for signs of lower extremity trauma, arthritis, or joint effusion.

lab investigations

 

  • protein S and protein C: coagulation inhibitors
  • antithrombin
  • lupus anticoagulant ratio
  • anticardiolipin antibodies
  • fasting homocysteine levels

 

 

D-dimer testing can be useful, though only as an adjunct

 

Diagnostic Imaging

 

duplex ultrasound (including serial ultrasound, if needed).

Non-invasive, portable.

Highly accurate for proximal clots; less so for popliteal veins.

 

absence of compression is the best finding.

Wells Clinical Model


Clinical Characteristic

Score

Active cancer (treatment ongoing within previous 6 months or palliative)

1

Paralysis, paresis, or recent plaster immobilization of the lower extremities

1

Recent bedrest >3 days or major surgery within 3 months requiring anesthesia

1

Localized tenderness of the deep veins of the leg

1

Entire leg swollen

1

Calf swelling >3 cm larger than asymptomatic side measured 10 cm below tibial tuberosity

1

Pitting edema confined to the symptomatic leg

1

Collateral superficial veins (not varicosed)

1

Previously documented DVT

1

Alternative diagnosis as likely as or more likely than DVT

-2

Modified from

 

A score of 0 or less indicates low probability, 1 or 2 indicates moderate probability, and 3 or more indicates high probability.
Use this probability table to determine level of probability (low, moderate, and high).  Then use follow up tests of D-Dimer and compression ultrasoundography to make more definitive diagnosis.

Differential Diagnosis

Differential diagnosis includes:

  • venous stasis and postphlebitic syndrome
  • lymphedema
  • cellulitis
  • superficial thrombophlebitis
  • ruptured popliteal cyst (more common with rheumatoid arthritis)
    • rapid onset, vs slow with DVT
  • muskuloskeletal injury

 

 

Diagnosis

The different causes of thrombosis can be primary (genetic), acquired, or some combination of the two.

 

A thrombophilic work-up includes:

 

 

 

Treatments

bedrest, elevate limb, give heparin.

Start heparin and warfarin together, to avoid warfarin's

in someoneone with no persisting risk factors, continue treatment for 3-6 months

if someone does have risk factors, continue perhaps indefinitely

 

clotbusting

antiplatelet agents

 

prevention of further clotting

 

 

treatment duration

reversible cause - 3 months

irreversible cause - indefinite

idiopathic - first episode - 6 months

second episode - indefinite

 

 

Resources and References

 

Wells PS, Anderson DR, Bormanis J, et al: Value of assessment of pretest probability of deep-vein thrombosis in clinical management. Lancet 1997;350:1795–1798.