The Doctor Recommended Guide to Understanding Deep Vein Thrombosis

What is Deep Vein Thrombosis (DVT)?

DVT is a condition where a Thrombosis, a blood clot, is formed in a deep vein of the vascular system. Veins help move blood to the heart so this condition can be fatal and immediate medical attention is necessary. 

In severe cases, the blood clot can break loose (embolize). The embolus (dislodged clot) can travel to the lungs and block arteries causing a pulmonary embolism (PE). A PE can be fatal. Most of the time, the blood clot will dissolve on its own. 

The CDC states that anyone traveling for more than four hours can be at risk of forming a blood clot.  The longer you are immobile, the greater your risk of developing a blood clot. Other risk factors include age, family history, obesity, and previous surgeries. Due to the wide range of risk factors, a medical professional must perform a deep review of the patient before determining if a DVT is suspected. 



Visit one of our Center for Vascular Medicine Locations for a comprehensive diagnosis. 

Deep Vein Thrombosis Signs & Symptoms

Symptoms of DVT will only be present in the affected limb.  Symptoms may range from mild to severe and may any combination of the symptoms below. In some cases of DVT, symptoms may not be present.

  • Swelling
  • Pain - typically worse with flexing the foot of the affected leg even when the pain is in the calf
  • Redness
  • Warm to touch

If the DVT has traveled to the lungs, known as a pulmonary embolism(PE), you may experience the following symptoms:

  • Chest pain
  • Shortness of breath
  • Persistent cough
  • Productive cough with pink discoloration or blood in the sputum

Deep Vein Thrombosis (DVT)

Deep Vein Thrombosis Causes & Risk Factors

DVT occurs when a clot forms that blocks normal blood flow in the deep veins.  This most often occurs in the large veins in the leg.

DVT develops in 350,000-600,000 people in the US per year.  Approximately 250,000 of these cases are a first time diagnosis. 

A shortlist of Risk factors can include the following:

  • Long periods of inactivity including:
    • Long flights
    • Long road trips
    • Long periods of limited activity due to recovery from illness or injury
  • Underlying medical conditions that make you more prone to developing DVT
    • Clotting disorders, which are typically hereditary. Many patients may have a family history of DVT. These may include:  
      • Cancer
      • Sickle Cell trait
      • Factor V Leiden
      • Protein C Deficiency 
      • Methylenetetrahydrofolate reductase (MTHFR)
      • Protein S Deficiency
  • Pregnancy, including the postpartum period for up to 6 weeks
  • Hormone replacement therapy(HRT)
    • Higher risk with oral therapy compared to transdermal HRT
  • Oral contraceptives (particularly with smokers)
  • Joint replacement surgeries(hip and knee)
  • Prior history of DVT
  • Obesity

Some DVTs may occur with no known related cause (unprovoked DVT)

List of what causes DVT and patients who have high risk

High-Risk Patients with DVT

Inheriting a blood-clotting disorder. Some people inherit a disorder that makes their blood clot more easily. This condition, on its own, might not cause blood clots unless combined with one or more of the other risk factors.

Prolonged bed rest, such as during a long hospital stay, or paralysis. When your legs remain still for long periods, your calf muscles don't contract and help blood circulate, which can increase the risk of blood clots.

Injury or surgery. Injury to your veins or surgery can increase the risk of blood clots.

Pregnancy. Pregnancy increases the pressure in the veins of your pelvis and legs. Women with an inherited clotting disorder are at increased risk. The risk of blood clots from pregnancy can continue for up to six weeks after childbirth.

Birth control pills (oral contraceptives) or hormone replacement therapy. Both can increase your blood's ability to clot.

Being overweight or obese. Being overweight increases the pressure in the veins of your pelvis and legs.

Smoking. Smoking affects blood clotting and circulation, which can increase your risk of DVT.

Cancer. Some forms of cancer increase the amount of clotting factors in your blood. Some forms of cancer treatment also increase the risk of blood clots.

Heart failure. This increases your risk of DVT and pulmonary embolism. The symptoms caused by even a small pulmonary embolism are more noticeable because people with heart failure have limited heart and lung function.

Inflammatory bowel disease. Bowel diseases, such as Crohn's disease or ulcerative colitis, increase the risk of DVT.

A personal or family history of deep vein thrombosis or pulmonary embolism.  If you or someone in your family has had one or both of these, you might be at greater risk of developing a DVT.

Age. Being older than 60 increases your risk of DVT, though DVT can occur at any age.

Sitting for long periods of time, such as when driving or flying. When your legs remain still for long periods, your calf muscles don't contract and help blood circulate. Blood clots can form in the calves of your legs if your calf muscles don't move for long periods.

Caprini Model used before surgery helps determine a patient's risk of developing a DVT

In 2005, Dr. Joseph Caprini created the “Caprini Model” to help physicians determine if patients are at risk of developing DVT. Today, this is widely used by vascular specialists to help determine patients' risk of developing DVT after surgery. 

The chart below shows a portion of the comprehensive assessment used by our medical professionals to determine DVT risk after surgery. 

Deep Vein Thrombosis (DVT)

The risk of DVT increases with the presence of more risk factors. CVM’s vascular specialists determine a score of 0-2, to be of low risk. Patients with a risk score of 3 or more should consider anticoagulation (anti-blood clot) medication to decrease the risk of developing DVT. In addition, compression therapy may be recommended. You can also read How do you know if you have blood clot after surgery?

Deep Vein Thrombosis (DVT)

Deep Vein Thrombosis Diagnosis

D-dimer testing may be initially performed to rule out the presence of DVT. A d-dimer test detects elevated protein levels in the blood which may indicate the presence of DVT. However, there are many other conditions that may also elevate blood protein levels so d-dimer is never relied upon as the sole diagnostic test. 

Duplex ultrasound studies should be done to confirm a diagnosis of DVT and determine location of the clot.  This study is done by placing an external probe on the skin in the area(s) of the suspected DVT.  The veins are visualized by sound waves that pass through the tissues of the limb.

If a PE is suspected, a CT (or ventilation/perfusion VQ) scan may be performed to evaluate for clots that have traveled to the lungs.


Deep Vein Thrombosis (DVT) Treatment

Venography is a test where dye is injected into the veins. This dye allows blood flow through the veins to be seen under x-ray, CT scan or MRI. 

Treatment of DVT depends on location of the DVT and may include use of compression stockings, anticoagulants, placement of IVC filter, thrombolysis or thrombectomy. 

DVT present in the veins below the knee may only require monitoring with repeat ultrasound studies and use of compression stockings depending on the particular vein the clot is present in.  

Anticoagulants are medications which prevent further formation of blood clots.  Anticoagulants come in a variety of forms including oral medications, intravenous(IV) medications and injectable medications. Anticoagulants are typically given for 3-6 months after initial diagnosis of DVT for patients at low risk for recurrence of DVT.  Further evaluation may be required by a Hematologist to determine if life long anticoagulation therapy is needed, especially in cases of recurrent or unprovoked DVT.

  • Heparin
    • IV Heparin:  given in a hospital setting when DVT is first diagnosed
    • Injectable: Unfractionated Heparin and Low Molecular Weight Heparin (Lovenox) may be given by subcutaneous injection under the skin
  • Coumadin/Warfarin
    • Oral medication taken once a day
    • INR levels must be monitored on a routine basis
    • Dosage adjustments may be required based on INR levels
    • Heparin is required initially until INR levels are within a therapeutic range
    • Dietary restrictions to foods high in Vitamin K (typically green leafy vegetables)    
  • Xarelto and Eliquis
    • No dietary restrictions
    • No need for routine blood level testing
    • No need for additional medications when first initiating therapy
  • Pradaxa
    • No dietary restrictions
    • No need for routine blood level testing
    • Heparin products should be given for the first 5-10 days after initiating therapy
    • May be used for DVT treatment but should not be used for DVT prevention.
  • IVC filter placement may be recommended in patients who have had PE with DVT history or in patients who are not able to be treated with anticoagulation therapy. IVC filters can be removable or permanent.
  • Thrombolysis and thrombectomy are indicated for cases where the DVT/PE is life-threatening, limb-threatening, organ threatening or pose long term complications 
  • Thrombolysis is delivery of a medication directly into the vein at the area of the DVT to dissolve the clot.  
  • Thrombectomy is mechanical removal of the clot by using special devices placed directly inside the vein.

This article is a comprehensive overview of Deep Vein Thrombosis. However, it should not take the place of speaking with a physician. If you are experiencing any of the symptoms listed above, or know someone who is, contact us today to schedule a consultation.

You can also view other vascular diseases below:

Pelvic Congestion Syndrome

May-Thurner Syndrome

Peripheral Arterial Disease (PAD)

Chronic Venous Insufficiency

Post-Thrombotic Syndrome


Yes, in many cases a DVT can be an emergent situation. There is no reason to delay seeking diagnosis and treatment. Never ignore the symptoms and seek medical attention immediately.

In most cases, the answer is no. Most patients will need prescription blood thinners. It is best to seek medical attention when you show signs or symptoms of DVT.

Patient that receive early diagnosis and treatment are more likely to have rapid resolution of their symptoms.

It can be, depending on the size and location of the clot.

Dr. Sanjiv Lakhanpal

Dr. Sanjiv Lakhanpal

Dr. Sanjiv Lakhanpal published in several medical research journals through the Lakhanpal Vein Foundation to help educate and raise awareness for vascular disease. He has been practicing medicine for 25 years, and is the founder of The Center for Vascular Medicine.