Deep Vein Thrombosis (DVT): Blood Clots, Warning Signs, and When to Act

Deep vein thrombosis (DVT) occurs when a blood clot forms in a deep vein, most commonly in the calf or thigh. Unlike surface clots, these clots are dangerous because they can travel to the lungs, causing a pulmonary embolism, which is a medical emergency.

In Canada, DVT is a significant health concern, particularly among individuals who are hospitalized, recently had surgery, are pregnant, or have limited mobility. If deep vein thrombosis is suspected, medical assessment should be sought immediately.

Signs and Symptoms of Deep Vein Thrombosis

Some individuals with DVT may have no noticeable symptoms, which is why awareness is critical. When symptoms do occur, they commonly include:

• Swelling in one leg (usually the calf or thigh)

• Pain or tenderness in the affected area

• Warmth or redness over the vein

A swollen and painful calf or thigh is one of the most common warning signs of deep vein thrombosis.

Why DVT Is Dangerous: Pulmonary Embolism Risk

The most serious complication of DVT is a pulmonary embolism (PE). This happens when part of the clot breaks off and travels to the lungs, blocking blood flow.

Seek emergency medical care immediately if any of the following occur:

• Chest pain

• Sudden shortness of breath

• Coughing up blood

• Dizziness, fainting, or collapse

Recognizing these symptoms quickly is a key component of advanced first aid and emergency response training.

Possible Causes and Risk Factors

Anything that slows blood flow or increases clotting risk can contribute to DVT. Common risk factors include:

• Prolonged bed rest or hospitalization

• Long periods of inactivity (e.g., long flights or car trips)

• Recent major surgery

• Serious illness such as cancer, heart failure, or infection

• Trauma such as fractures or motor vehicle accidents

• Use of estrogen-containing oral contraceptives or hormone therapy

DVT is also more common:

• During pregnancy or shortly after childbirth

• In individuals with inherited clotting disorders

How Deep Vein Thrombosis Is Diagnosed

If a healthcare provider believes the risk of DVT is high, an ultrasound of the affected limb is typically ordered to confirm the presence of a clot.

Not every case of leg pain requires imaging—particularly if the individual is walking comfortably—but clinical judgment is essential.

Management and Treatment

Once diagnosed, DVT is usually treated with:

• Anticoagulant (blood-thinning) medications

• Compression stockings to reduce swelling and improve circulation

Early treatment significantly lowers the risk of pulmonary embolism and long-term complications.

Preventing Deep Vein Thrombosis

If travelling, hospitalized, or at higher risk, preventive measures include:

• Wearing compression stockings

• Moving legs and feet frequently

• Staying well hydrated

• Maintaining a healthy weight

• Avoiding smoking

These preventive strategies are frequently discussed in intermediate and advanced first aid courses, particularly in workplace and healthcare settings.

Why DVT Awareness Matters in First Aid Training

While DVT itself is not treated with first aid, its complications are life-threatening emergencies. First aiders trained in medical recognition are better prepared to:

• Identify red-flag symptoms

• Escalate care appropriately

• Activate emergency medical services without delay

Educational Disclaimer:
This information is provided for general education and awareness only and does not replace professional medical advice, diagnosis, or treatment. Deep vein thrombosis requires medical assessment and prescription treatment. First aid and CPR training focuses on early recognition, emergency response, and escalation of care, not diagnosis or medication management.