Deep Vein Thrombosis: Symptoms, Diagnosis, and Treatment

Fact checked by Olga Sadouskaya, MD
Clinical Pharmacologist, Chief Medical Officer

If your veins are damaged, or your blood flow is too slow, a thrombus — blood clot — can form in your deep veins, causing a condition known as deep vein thrombosis (DVT), sometimes also called venous thrombosis.

Your veins may become fully or partially blocked due to blood clots. Although most cases of DVT arise in the lower legs, thighs, and pelvis, they can also occur in the arms (deep vein thrombosis of the arm), brain, intestines, liver, and kidneys.

Continue reading to learn about the risk factors and early signs of DVT and how to diagnose it with ultrasound and other tests.

Early signs and symptoms of deep vein thrombosis

Get in touch with your doctor if you experience any of the following symptoms of DVT.

  • Swelling of your legs: It may occur at the site where a blood clot has developed. In extreme circumstances, it can affect the entire afflicted leg. The reason for this is that DVT weakens veins and valves. When blood pools in your legs due to weak veins and valves, you may experience discomfort and swelling. It is possible for swelling to persist even after DVT therapy.
  • Redness: As a result of blood vessels being blocked, DVT can produce inflammation and skin redness in the arms and legs. In certain cases, the damaged vein may be followed by a thin, red line.
A woman with deep vein thrombosis pain in her legs
  • Pain in the leg: Pain and tenderness in the affected region are common symptoms of a clot’s progression. It might start as mild discomfort and progress to searing, throbbing pain. Prolonged standing or walking might intensify discomfort. However, unlike the discomfort from a pulled muscle, the pain from a deep vein thrombosis in the leg does not go away with time.
  • Warmth: One of the earliest signs of deep vein thrombosis is a feeling of warmth. Only the affected part of the body will feel warm; the rest of your body will still be at a normal temperature. Sometimes, only the spot directly over the blocked vein will feel warm to the touch.
  • Leg сramps: Most of us have experienced a painful leg cramp at some point in our lives. Most muscle cramps can be relieved by stretching or walking, but leg cramps caused by DVT persist or intensify with time. DVT-related cramping requires medical care before it worsens and poses a health risk. A number of different conditions can cause leg cramps, but one way to determine if you have deep vein thrombosis instead of a regular leg cramp is to bend your foot at the ankle so that your toes point upward. It should ease the pain of a typical cramp. An increase in pain is common with a blood clot.

Does DVT pain come and go, or is it constant?

When it becomes stuck in a vein, a blood clot cannot move freely in and out of that vein. If it’s causing discomfort, cramps, or a painful feeling, it will be constant rather than occasional.

Virchow’s triad: Risk factors for DVT

One of the first physicians to describe DVT at the cellular level was Rudolf Virchow, who held the view that cellular pathology was ultimately responsible for most diseases, including pathological thrombosis. He is regarded as the father of modern pathology.

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Virchow theorized that pulmonary artery emboluses develop from peripheral/distant thrombosis. He made an effort to describe what causes a thrombus to break away from a vein in the body’s periphery, move to the right side of the heart, and enter the pulmonary arteries.

Virchow's triad describes three factors that contribute to the development of thrombosis:

  • Intravascular vessel wall damage
  • Stasis of flow of blood
  • A hypercoagulable state

How is deep vein thrombosis diagnosed?

Your doctor will do a physical exam and ask you questions about your symptoms in order to make a diagnosis of DVT. Your health care provider will examine your legs for any signs of swelling, soreness, or unusual skin color.

If your doctor thinks you’re at a low risk for DVT, you won’t need as many tests as someone who’s at a higher risk. Some of the tests used to diagnose DVT include the following.

DVT ultrasound

Due to its accessibility and lack of discomfort, this is the go-to method for diagnosing DVT. It’s also the most accurate noninvasive diagnostic method for DVT. Ultrasound waves are used in this diagnostic procedure to see blood flow and clots in the veins.

A technician conducting a vascular ultrasound will push on your arm or leg while they scan the veins and arteries.

A blood clot may be visible on ultrasound if the pressure does not cause the vein to constrict.

Your doctor may choose to do another imaging test in addition to the duplex ultrasound if the results are unclear.


In this invasive procedure, your doctor will numb the skin on your neck or groin and insert a catheter into your veins to inject a specific dye (contrast material) to detect the presence of blood clots. Even though venography is rarely performed today, it may be essential in certain situations.

Blood test

A D-dimer blood test measures a protein that is released as a clot dissolves.

There is a strong probability that you have a clot if the levels of the chemical are high and you have risk factors for DVT. If your levels are normal, and you don’t have many risk factors, then DVT is less likely.

Your doctor may order further tests to confirm a diagnosis of blood clots because the D-dimer blood test may also show other conditions.

DVT prophylaxis: Ways to prevent and treat blood clots

Only specific groups of people require prophylactic therapy in order to reduce the risk of deep vein thrombosis. These include:

  • Critically ill patients
  • Immobile patients
  • People with cancer
  • Pregnant women
  • Long-distance travelers
  • Those who plan to undergo or recently had surgery
Medications for DVT prophylaxis

Preventive treatments for deep vein thrombosis in people after surgery may include:

  • Mechanical therapy
  • Drug therapy

The patient’s risk profile, the surgical procedure they have planned or had already (if any), the anticipated length of preventive therapy, any potential contraindications or bad effects, the relative cost, the convenience of usage, and local practice all play a role in the decision. Your doctor will help you decide which course of action is best for you.

Mechanical therapy

In post-surgical patients, veins can heal more quickly after surgery if the patient’s legs are kept elevated and they are not forced into a dependent posture for an extended period of time.

Except for low-risk surgical patients and some hospitalized medical patients, the effectiveness of graded deep vein thrombosis compression stockings is questionable.

However, stockings may provide additional protection when used in conjunction with other strategies. External compression is applied to the lower legs and, in some cases, the thighs with the use of a pump in a technique known as intermittent pneumatic compression.

Drug therapy

Although aspirin is more effective than a placebo, it is not recommended as a first-line treatment for avoiding DVT and pulmonary embolism since it is less effective than low molecular-weight heparin and warfarin.

Subcutaneous injections of low-dose unfractionated heparin may be required before and after surgery to prevent blood clots during recovery for bedbound patients.

When it comes to DVT prophylaxis using medications, there are several factors to consider. Common drugs for DVT prevention include low-molecular-weight heparin, unfractionated heparin, fondaparinux, direct oral anticoagulants, and warfarin. Only your doctor can find the option that works best for you.

Bottom line

Symptoms of deep vein thrombosis may be similar to those of other conditions. However, nearly half of the time, people with this type of blood clot in a deep vein (often in the leg) have no symptoms at all.

Stay vigilant for symptoms if you are over the age of 60, a smoker, overweight, or a sedentary worker. If you suspect you have DVT, you should consult your doctor right away.

February 22, 2023