The veins of the legs need to work against gravity to return blood back to the heart. Typically,  contractions of our leg muscles during everyday activities like walking and standing, help to “pump” blood upwards through the veins. However, when a person is immobile for a long period of time due to illness, hospitalization, or extended car or plane travel, this can cause blood to pool in the lower extremities. When blood pools and becomes stagnant it increases the likelihood of clot formation. In addition, broken bones, injuries, surgery, or any sort of trauma to leg can promote the formation of blood clots. Certain groups of people may be at higher risk for developing DVT due to hereditary clotting disorders or acquired factors such as: 

• Cancer or chemotherapy treatment 
• Pregnancy 
• Use of hormonal birth control or hormone replacement therapy 
• Recent surgery or hospitalization 
• Inflammatory bowel disease 
• Age
• Obesity 
• Smoking 
  

Signs and symptoms of a DVT can include leg pain, swelling, redness, warmth, or discoloration. Although, it is possible to have a DVT and with no symptoms at all. Thus, it is important to know your personal risk factors and discuss them with your doctor. DVTs can be treated with medications that can dissolve clots or prevent more clots from forming. Also, compression stockings can be worn to aid in blood flow to prevent additional clots. In most cases, medical treatment will help the DVT be reabsorbed by the body and symptoms will subside.  Yet, some individuals will develop persistent pain and swelling in the affected leg, known as post-thrombosis syndrome.   

Pulmonary Embolism (PE) 
The most serious complications of a DVT is the formation of PE, which occurs when a clot breaks free from the leg and becomes lodged in the lungs. This causes permanent damage to the lung, low levels of oxygen in the blood, and damage to other organs such as the heart [3]. PEs can be life threatening, as 10-30% of individuals will die within one month of diagnosis [4]. Although PEs may be asymptomatic, some signs and symptoms may include: shortness of breath, chest pain, rapid heartbeat, and cough. You may appreciate that these symptoms can be indicative of other injuries or illness, so PEs can be difficult to diagnose. Increased awareness and education, on both the part of the patient and physician, may lead to improved diagnosis and treatment and reduced mortality for this serious condition. 

Women and VTE: 
Women may be at greater risk for developing VTE, which includes both DVT and PE, at different points throughout their lifespan. During a woman’s reproductive years, the overall risk of developing VTE is low (affecting 7 in 10,000 women per year) yet use of hormonal contraceptives may increase this risk by 4 times [4]. Hormone replacement therapy during menopause may also cause a 2-4 fold higher risk, although this may depend on the type of estrogen therapy and route of administration [4]. However, a woman is a greatest risk of developing VTE during pregnancy and the postpartum period (affecting 20 in 10,000 women per year) due to an increase in clotting factors, which are normally produced to prevent hemorrhage after birth, and pressure put on the pelvic and leg veins due to the growing uterus. 

Reducing Your Risk: 
Be sure to discuss your individual risk factors with your doctor, especially prior to any type of hospitalization or surgery. When traveling, be sure to take a break from sitting every hour so and drink plenty of fluids. For additional resources and information on VTE please consider visiting the following: 

American Heart Association 
National Institutes of Health – National Heart, Lung, and Blood Institute 
Northwestern Medicine 

References: 
1. Wendelboe et al., J Thromb Haemost. 2015;13(8):1365-71.
2. Cushman and Creager, JAMA. 2015; 314(18): 1913–1914.
3. MedlinePlus – Pulmonary Embolism 

4. Centers for Disease Control
5. Heit et al., J Thromb Thrombolysis. 2016; 41: 3–14.

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