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Published on: 2/24/2026

Is it DVT? Why Deep Vein Thrombosis occurs and your medical next steps

Deep vein thrombosis is a blood clot in a deep leg vein that can cause one-sided swelling, pain, warmth, or redness and can lead to a life-threatening pulmonary embolism; it occurs when blood flow slows, blood clots more easily, or a vein is damaged. There are several factors to consider and some conditions can mimic it; see below for risk factors, symptom clues, and how doctors confirm it.

If you suspect it, do not massage the leg and seek prompt care for evaluation with D-dimer and ultrasound, and go to the ER immediately for chest pain, shortness of breath, fainting, or coughing blood, with treatment, prevention, and next-step details outlined below.

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Explanation

Is It Deep Vein Thrombosis (DVT)?

Why Deep Vein Thrombosis Occurs and What to Do Next

If you're worried about deep vein thrombosis (DVT), you're not alone. It's a serious but treatable condition. Knowing what it is, why it happens, and what steps to take can help you act quickly and confidently.

This guide explains:

  • What deep vein thrombosis is
  • Common signs and symptoms
  • Why DVT occurs
  • Who is at higher risk
  • What doctors do to diagnose and treat it
  • What you should do next

What Is Deep Vein Thrombosis?

Deep vein thrombosis (DVT) is a blood clot that forms in a deep vein, usually in the leg. Most often, it develops in the:

  • Calf
  • Thigh
  • Pelvis

Less commonly, DVT can occur in the arms.

The main concern with deep vein thrombosis is not just the clot itself, but what can happen if part of it breaks off and travels to the lungs. This can cause a pulmonary embolism (PE), which can be life-threatening and requires immediate medical attention.

That said, many cases of DVT are successfully treated when caught early.


Common Symptoms of Deep Vein Thrombosis

Not everyone with deep vein thrombosis has symptoms. But when symptoms do appear, they often include:

  • Swelling in one leg (rarely both)
  • Pain or tenderness in the calf or thigh
  • Warmth in the affected area
  • Red or discolored skin
  • Leg fatigue or heaviness

Symptoms typically affect only one leg, which is an important clue.

Emergency Symptoms

Seek urgent medical care if you notice:

  • Sudden shortness of breath
  • Chest pain (especially when breathing deeply)
  • Rapid heartbeat
  • Coughing up blood

These could be signs of a pulmonary embolism.

If you're experiencing any of these symptoms and want to better understand your risk level, try Ubie's free AI-powered Deep Vein Thrombosis (DVT) symptom checker before speaking with a healthcare provider.


Why Does Deep Vein Thrombosis Occur?

Doctors often explain deep vein thrombosis using something called Virchow's Triad. It describes three main factors that increase clot risk:

1. Slowed Blood Flow

When blood moves too slowly through the veins, it's more likely to clot.

This can happen during:

  • Long flights or car rides
  • Extended bed rest
  • Hospital stays
  • Recovery after surgery
  • Paralysis or limited mobility

Even sitting for long periods without moving your legs can contribute.


2. Blood That Clots Too Easily

Some people have blood that is more prone to clotting due to:

  • Genetic clotting disorders
  • Cancer
  • Hormone therapy or birth control pills
  • Pregnancy and postpartum period
  • Certain autoimmune conditions

Dehydration can also thicken the blood, slightly increasing risk.


3. Damage to the Vein

Injury to a vein can trigger clot formation. This may occur due to:

  • Surgery (especially orthopedic surgery)
  • Trauma or fractures
  • IV lines or catheters
  • Inflammation of blood vessels

Who Is at Higher Risk for Deep Vein Thrombosis?

You may be at increased risk if you:

  • Are over age 60
  • Have recently had surgery
  • Are pregnant or recently gave birth
  • Use estrogen-containing medications
  • Have obesity
  • Smoke
  • Have a personal or family history of blood clots
  • Have cancer or are receiving chemotherapy
  • Sit for prolonged periods (desk job, travel)

Risk increases when multiple factors combine.


Is It Really DVT?

Leg swelling and pain are common, and most cases are not deep vein thrombosis. Other causes include:

  • Muscle strain
  • Cellulitis (skin infection)
  • Varicose veins
  • Baker's cyst
  • Chronic venous insufficiency

Because symptoms overlap, you cannot reliably diagnose DVT at home.

If you suspect deep vein thrombosis, it's important to speak to a doctor promptly. Waiting can increase the risk of complications.


How Doctors Diagnose Deep Vein Thrombosis

A doctor will typically evaluate:

1. Your Symptoms and Risk Factors

They may use a clinical scoring tool to estimate the likelihood of DVT.

2. D-Dimer Blood Test

This test measures a substance released when clots break down.

  • A normal result often helps rule out DVT in low-risk patients.
  • An elevated result does not confirm DVT but signals need for imaging.

3. Ultrasound (Compression Ultrasound)

This is the most common and reliable test for diagnosing deep vein thrombosis.

It is:

  • Non-invasive
  • Painless
  • Widely available

In rare cases, additional imaging may be needed.


What Happens If You Are Diagnosed With Deep Vein Thrombosis?

The good news: deep vein thrombosis is treatable.

Main Treatment: Blood Thinners (Anticoagulants)

These medications:

  • Prevent the clot from growing
  • Reduce the risk of pulmonary embolism
  • Lower the chance of new clots forming

Common options include:

  • Direct oral anticoagulants (DOACs)
  • Heparin
  • Warfarin

Treatment usually lasts:

  • 3 months for many first-time cases
  • Longer if risk factors persist

Your doctor will determine the safest plan for you.


In Severe Cases

Rarely, additional treatment may be needed:

  • Clot-dissolving medication (thrombolysis)
  • Mechanical clot removal
  • Placement of an inferior vena cava (IVC) filter

These are typically reserved for high-risk or complicated cases.


What Are the Risks if DVT Is Not Treated?

Untreated deep vein thrombosis can lead to:

Pulmonary Embolism

A potentially life-threatening condition where the clot travels to the lungs.

Post-Thrombotic Syndrome

Long-term leg symptoms such as:

  • Chronic swelling
  • Pain
  • Skin discoloration
  • Ulcers

Early diagnosis and treatment significantly reduce these risks.


What Should You Do Next?

If you think you might have deep vein thrombosis, take these steps:

  • Do not massage the leg
  • Avoid intense physical activity
  • Seek medical care promptly
  • Go to urgent care or the ER if symptoms are severe

If you're unsure about your symptoms, you can use Ubie's free online Deep Vein Thrombosis (DVT) symptom checker to get personalized insights in just a few minutes and determine whether you should seek immediate medical attention.

However, no online tool replaces a real medical evaluation.


When to Speak to a Doctor Immediately

Call emergency services or go to the nearest emergency room if you have:

  • Sudden chest pain
  • Shortness of breath
  • Fainting
  • Coughing up blood

These could indicate a pulmonary embolism, which requires urgent care.


Preventing Deep Vein Thrombosis

You can reduce your risk by:

  • Moving regularly during long travel (every 1–2 hours)
  • Staying hydrated
  • Maintaining a healthy weight
  • Quitting smoking
  • Following your doctor's instructions after surgery
  • Wearing compression stockings if recommended

If you are at high risk, your doctor may prescribe preventive blood thinners.


Final Thoughts

Deep vein thrombosis is a serious condition—but it is manageable and often fully treatable when identified early.

If you are experiencing one-sided leg swelling, pain, warmth, or redness, don't ignore it. While many cases turn out to be something less serious, DVT is not something to self-diagnose or wait out.

Consider starting with a free online symptom check, and most importantly, speak to a doctor if your symptoms could represent something serious or life-threatening. Acting early can make all the difference.

Your health is too important to guess.

(References)

  • * Kearon C, et al. Diagnosis and Management of VTE: A Review. JAMA. 2021 Jul 13;326(2):182-192. doi: 10.1001/jama.2021.10023. PMID: 34255018.

  • * Konstantinides SV, et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European Respiratory Society (ERS). Eur Heart J. 2020 Jan 21;41(4):543-603. doi: 10.1093/eurheartj/ehz405. PMID: 31505067.

  • * Mousa SA, et al. Pathophysiology of Deep Vein Thrombosis: A Critical Appraisal of Virchow's Triad. Adv Exp Med Biol. 2017;906:1-12. doi: 10.1007/5584_2016_62. PMID: 27957777.

  • * Stevens SM, et al. Antithrombotic Therapy for VTE Disease: CHEST Guideline and Expert Panel Report. Chest. 2021 May;159(5):1930-1951. doi: 10.1016/j.chest.2021.02.013. PMID: 33676274.

  • * Cushman M. Epidemiology and risk factors for venous thrombosis. Semin Hematol. 2017 Jan;54(1):1-10. doi: 10.1053/j.seminhematol.2017.01.002. PMID: 28410769.

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