Virchow's triad includes all of the following, EXCEPT-
Virchow's triad refers to three primary influences that predispose to thrombus formation.


Endothelial injury (or vascular injury)
Stasis or turbulence of blood flow
Blood hypercoagulability


Virchow's triad should be the cornerstone for assessment of risk factors for deep venous thrombosis.
Stasis can occur with venous insufficiency, severe heart failure, or prolonged bed rest or immobility of an extremity following coma, pelvic or limb fracture, paralysis, extended aeroplane travel, or a lengthy operation.
Endothelial injury can result from direct trauma (severed vein, venous cannulation, or transvenous pacing) or local irritation secondary to the infusion of chemotherapy, previous DVT, or phlebitis.

Damaged endothelium leads to platelet aggregation, degranulation and formation of thrombosis as well as vasoconstriction ad activation of the coagulation cascade.
The hypercoagulable state can be inherited or acquired.
These are

def. of antithrombin III, protein C or S
increased homocysteine
factor V Leiden mutation
prothrombin gene mutation
antiphospholipid syndrome
paroxysmal nocturnal hemoglobinuria
malignancy (lung cancer - most commonly pancreas, prostate, breast, ovary etc...)
nephrotic syndrome
pregnancy, high dose estrogen therapy or OCPs.

Some important questions on deep vein thrombosis

Homan's sign → Calf tenderness on forced ankle dorsiflexion.
Phlegmasia alba dolens → Painful white leg
Phlegmasia cerulea dolens → Painful blue leg
Moses Sign → Calf tenderness on direct pressure on the calf
Pratt's Sign → Calf tenderness on squeezing the calf from the sides. Duplex ultrasound is the diagnostic modality of choice in deep vein thrombosis.
Venous stasis
Injury to veins
Blood hypercoagulability
Venous thrombosis