Deep Vein Thrombosis


The femoral vein (in the thigh), the iliac veins (in the pelvis), and the inferior vena cava (in the abdomen) are places of potential DVT extension.


In the 18th Century, the increased incidence of deep vein thrombosis (DVT) in women after childbirth was noticed, and in the late 1700s, a public health recommendation was issued to encourage women to breast feed as a means to prevent this phenomenon. DVT was called “milk leg“, as it was thought to result from milk building up in the leg.


Rudolf Virchow MD (1821-1902), German physician and pathologist, is known for elucidating the mechanism of pulmonary thrombo embolism, coining the term embolism and thrombosis. In 1856, he published what is referred to as Virchow’s triad, the three major causes of thrombosis. The triad provides the theoretical framework for the current explanation of venous thrombosis, although it was focused on the effect of a foreign body in the venous system and the conditions required for clot propagation. Virchow noted that blood clots in the pulmonary artery originate first from venous thrombi, stating: “The detachment of larger or smaller fragments from the end of the softening thrombus which are carried along by the current of blood and driven into remote vessels. This gives rise to the very frequent process on which I have bestowed the name of Embolia“. Having made these initial discoveries based on autopsies, he proceeded to put forward a scientific hypothesis; that pulmonary thrombi are transported from the veins of the leg and that the blood has the ability to carry such an object. He then proceeded to prove this hypothesis through well-designed experiments, repeated numerous times to consolidate evidence, and with meticulously detailed methodology. This work rebuked a claim made by the eminent French pathologist Jean Cruveilhier that phlebitis led to clot development and therefore coagulation was the main consequence of venous inflammation. This was a view held by many before Virchow’s work.


Related to this research, Virchow described the factors contributing to venous thrombosis, Virchow’s triad.


Virchow’s triad



Virchow’s triad or the triad of Virchow describes the three broad categories of factors that are thought to contribute to thrombosis.


  1. Hypercoagulability
  2. Hemodynamic changes (stasis, turbulence)
  3. Endothelial injury/dysfunction


Although named after Virchow, the elements comprising Virchow’s triad were neither proposed by Virchow, nor did he ever suggest a triad to describe the pathogenesis of venous thrombosis. In fact, it was decades following Virchow’s death before a consensus was reached proposing that thrombosis is the result of alterations in blood flow, vascular endothelial injury, or alterations in the constitution of the blood. Still, the modern understanding of the factors leading to embolism is similar to the description provided by Virchow. Its nebulous origins notwithstanding, Virchow’s triad remains a useful concept for clinicians and pathologists alike in understanding the contributors to thrombosis.


The triad consists of three components:


Virchow’s Modern Notes
Phenomena of interrupted blood-flow Stasis The first category, alterations in normal blood flow, refers to several situations. These include venous stasis, mitral stenosis, prolonged immobility (as on a long plane or car ride, bed bound during hospitalization) and varicose veins. The equivalence of Virchow’s version and the modern version has been disputed.
Phenomena associated with irritation of the vessel and its vicinity Endothelial injury or vessel wall injury The second category, injuries and/or trauma to endothelium includes vessel piercings and damages arising from shear stress or hypertension. This category is ruled by surface phenomena and contact with procoagulant surfaces, such as bacteria, shards of foreign materials, biomaterials of implants or medical devices, membranes of activated platelets, and membranes of monocytes in chronic inflammation.
Phenomena of blood-coagulation Hypercoagulability The last category, alterations in the constitution of blood, has numerous possible risk factors such as hyperviscosity, deficiency of antithrombin III, protein C or S deficiency, Leiden V factor, nephrotic syndrome, changes after severe trauma or burn, disseminated cancer, late pregnancy and delivery, race, advanced age, cigarette smoking, hormonal contraceptives, and obesity. All of these risk factors can cause the situation called hypercoagulability (excessively easy clotting of blood).


Multiple pharmacological therapies for DVT were introduced in the 20th century: oral anticoagulants in the 1940s, subcutaneous LDUH in 1962, and subcutaneous LMWH in 1982. Diagnoses were commonly performed by impedance plethysmography in the 1970s and 1980s. Today, the most used diagnostic tool is the Doppler ultrasound techniques, with their increased sensitivity and specificity, performed by a radiologist.



Leave a Reply

You must be logged in to post a comment.