DVTs
Virchow's triad was first elaborated upon in 1860, and still remains important.
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;
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.
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.
D-dimer testing can be useful, though only as an adjunct
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 includes:
The different causes of thrombosis can be primary (genetic), acquired, or some combination of the two.
A thrombophilic work-up includes:
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
reversible cause - 3 months
irreversible cause - indefinite
idiopathic - first episode - 6 months
second episode - indefinite
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.