What is deep vein thrombosis (DVT)?

Thrombosis occurs when a blood clot develops and blocks a blood vessel. Deep vein thrombosis develops when a blood clot forms in the deeper veins, often in the legs. In severe cases, this can lead to a pulmonary embolism (when a blood clot travels to a lung artery where it suddenly blocks blood flow).

What causes DVT?

Extended periods of time standing or sitting can cause blood to pool in the lower limbs. This increases the risk of developing deep vein thrombosis. Additional contributing factors for DVT include dehydration and sluggish blood flow.

Workplaces that require extended periods of time standing or sitting without proper breaks and without enough time to stay hydrated increase workers’ risk of developing DVT. These conditions of employment sometimes occur because of cutbacks or being short-staffed.

Who is at risk?

Anyone can develop deep vein thrombosis.

CUPE members are at greater risk of developing DVT if they:

  • Are over 60 years old
  • Have family history of DVT
  • Have medical conditions such as heart disease, cancer, lung disease
  • Have had recent surgery or suffered trauma, particularly to the lower part of the body (hip or knee surgery, spinal cord injury or a fracture of a lower limb)
  • Are on certain oral contraceptives or hormone replacement therapy
  • Are pregnant
  • Are a smoker
  • Are overweight

Occupational risk

Those who work in industries that require them to remain in a static position for prolonged periods (such as standing at a counter or sitting) are at greater risk. This includes drivers, health care staff, kitchen staff, and anyone who works long shifts without the ability to change position or take sufficient breaks.

Flight attendants are at additional risk because of extended work times in dry cabin air, with lower oxygen levels and constantly changing cabin pressure due to multiple take offs and landings.

What are the health hazards?

Deep vein thrombosis is not life-threatening on its own. The risk occurs when part of a blood clot breaks off and moves through the circulatory system. The blood clot can end up blocking an artery, causing a pulmonary embolism, a stroke, or a heart attack. These can be life threatening.

Signs and symptoms do not occur all at once, and may include:

  • Soreness in the affected leg that can feel like a pulled muscle (sometimes very severe)
  • Swelling in the leg
  • Discoloration that resembles a bruise and that can appear red, purple, or blue
  • Tingling, itchiness, or warmth near the affected area
  • “Travelling” symptoms, moving from one part of the leg to another
  • Chest pain
  • Coughing
  • Vomiting
  • Increased heart rate
  • Sudden shortness of breath

Unfortunately, these are common in many conditions and may be misdiagnosed. If you develop signs or symptoms of deep vein thrombosis, seek emergency medical assistance.

Preventative measures

Being proactive is the best practice when it comes to reducing the chances of developing deep vein thrombosis.

Health and safety committees should discuss the work-related factors that increase the risk of DVT at joint committee meetings with the employer and make recommendations to limit exposure to those factors.

For workers who are at high risk of experiencing DVT, medical-grade compression socks or tights can reduce the risk. These socks are made of strong, stretchy materials designed to put pressure on legs and ankles to help blood flow. This curbs the pooling of blood and swelling in the legs.

Workers should also take time to move around to avoid static postures whenever possible. If you are unable to walk around, slowly walk in place.

Remember, repeated movement and muscle contractions help push the blood through the veins, while limited muscle contractions and lack of movement reduce blood flow. If you are required to sit for long periods, stand and walk as often as you can (ideally every 15 minutes), or consider a sit-stand style workstation. Other practices that can help include staying hydrated, and wearing loose, comfortable clothing that does not restrict blood flow to the upper body. These are particularly important habits when working long shifts.

Proper staffing can help ensure employees are able to take precautionary measures like regularly scheduled breaks.

Access to personal protective equipment

Employers have a legal duty to maintain a healthy and safe workspace. However, many are resistant to providing proper personal protective equipment like compression socks until a worker has developed a medical condition. CUPE members who are concerned about DVT should contact their locals to learn about how to work with workplace- related benefit or insurance providers to determine coverage and application processes. Where coverage does not exist, locals should evaluate the need to include the proactive supply of compression stockings in the next round of negotiations or add medical-grade compression socks and/or tights as part of the uniform choice.


For more information contact:

CUPE National Health and Safety Branch
1375 St-Laurent Boulevard
Tel: (613) 237-1590
Fax: (613) 237-5508
Email: health_safety@cupe.ca