No Blood Flowing in Those Veins: Venous Thrombosis

Clots in veins located in muscles can result in a pulmonary embolism, blood drainage disorders in limbs and more. Dr. Alexander Kantarovsky, a specialist in vascular surgery at Hillel Yaffe Medical Center's Vascular Surgery Unit, explains venous thrombosis and the methods used to diagnose, treat and prevent the disorder

What is deep vein thrombosis (DVT)? DVT is a blood clot that appears in deep veins (veins located in muscles. Most of the blood in limbs drains through the deep venous system) of the limbs.

There are three aspects of the classic explanation for the development of a deep vein thrombosis:

  1. Bruising of the vein wall – traumatic strike or injury
  2. Lack of circulation of blood in the limb veins, for example under a cast and/or following paralysis. During lengthy surgery or a long flight, etc. 
  3. Dysfunction of the body's clotting system

The body has two mechanisms – one that dissolves clots and one that generates them (the body's defense against bleeding). When any acute trauma occurs that results in the formation of blood clots, the clot begins to grow and spread in the vein, creating a thrombosis that can be diagnosed. From a certain size, the thrombosis can even be seen in imaging.  


X-ray of blood vessels

 What are the dangers of thrombosis?  

  • Pulmonary embolism -  A condition in which blood clots reach the lungs through the blood stream and block the passage of blood to the lungs, potentially endangering the patient. Breathing becomes inefficient, and blood fails to oxygenize. Respiratory distress occurs to the point of suffocation. A pulmonary embolism can appear in a mild form of a cough and progress to the point of respiratory failure and death.
  • Post-thrombotic syndrome – A local complication. In this condition, damage is caused in the limb itself as a result of disruptions to blood drainage from the limb due to blockage of some of the veins by clots or destruction of deep vein valves. 

Risk Factors:

  • History of deep vein thrombosis – If someone has a history of DVT, the condition might return. There is also hereditary risk, if someone in the family suffers from DVT. 
  • Malignant tumors in the body – There are cases in which thrombosis occurs prior to the tumor, indicating tumor formation. 
  • Lengthy travel when sitting or on a flight (over five hours) – Prolonged sitting without movement and mobility, dehydration due to the air in the plane and consumption of alcoholic beverages changes during a flight. The exact reason is unclear, but it has been known to happen.    
  • Obesity. 
  • Surgery under anesthesia that last longer than 30 minutes, particularly gynecological surgery, orthopedic surgery and neurosurgery. 
  • Lack of mobility due to stroke or cast. 
  • Hormone therapy such as the birth control pill or hormone therapy during menopause. 
  • Particularly severe trauma to the lower limbs (car accident for example). 
  • Thrombophilia. 


Prevention includes:  

  • Drug therapy. 
  • Immediate mobility – Make sure to remain in movement. Get up occasionally on a flight. Undergo physical therapy following surgery. Get up as soon as possible after surgery. 
  • Elastic band – elastic sock – reduces swelling of the leg (prevents edema) and increases blood flow through the veins. 
  • Mechanical therapy – Instruments that generate intermittent pressure on the limb. Can be connected to the patient during surgery to prevent thrombosis. These devices are also used as part of physical therapy with paralyzed patients. 

Remember: a pulmonary embolism is the most common cause of unexpected death following hysterectomies, abdominal surgeries in general surgery and orthopedic surgery, particularly joint replacement.


In approximately 50% of cases, there are no identifying symptoms of venous thrombosis. The symptoms that can appear generally do so late, as swelling of the shin, local sensitivity, redness. 

Diagnosis is made in several ways: 

  • Duplex test (combination of an ultrasound and Doppler device – the first shows the image, and the second enables an assessment of blood flow). The duplex is a non-invasive test, but is less effective in extremely small veins or in the pelvis. 
  • CT scan – Excellent in diagnosing thrombosis in pelvic veins and in the diagnosis of pulmonary embolisms, but involves radiation and administration of a contrast medium. 
  • D-dimer blood test – Examines the concentration of the material generated during the dissolution of the thrombosis. The test is effective, but only when the result is negative. In other words, when the result is normal – there is no thrombosis. However, when the concentration of material is high, it does not indicate anything because a high concentration can occur under other conditions as well. 


  • The most basic treatment involves the administration of an anticoagulant by injection and continued treatment with pills for several months (three to six months). The length of anti-coagulation therapy depends on the status of the individual's thrombophilia. 
  • Elastic band (elastic socks) – Prevent post-thrombatic syndrome, which is manifested as chronic edema, constant changes in skin and the onset of hard to heal ulcers (constantly recurring open wounds). Use of elastic socks must begin immediately following diagnosis. The patient must be moved immediately after the elastic socks have been put on (in contrast with the previous standard approach that recommended that the patient lie in bed for several days). The sock must be used for at least two years. It has been proven to reduce post-thrombotic syndrome by at least 50%. 
  • Thrombolytic therapy (dissolving the clot) – Treatment primarily designed for thrombosis of the pelvic veins. Thrombolytic therapy is invasive and requires the insertion of a catheter into the vein with the clot as well as the drip of the clot dissolving medication over the course of several hours. The drug is primarily given when diagnosis is made early and large veins are involved such as the pelvic or hip veins. An alternative to this treatment is surgery to remove the clots, which is primarily performed when thrombolytic therapy is contraindicated.  
  • Technology of inserting a special catheter to mechanically dissolve clots in the veins. Ideal for thrombolytic therapy, it is faster and safer. 


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