What Causes a Blood Clot in the Calf?

A blood clot in the calf, also known as a deep vein thrombus, can form when there is excessive clumping together of platelets and red blood cells in a blood vessel. There are several factors that can contribute to the development of a blood clot in the calf that range from environmental influences, to personal actions, to underlying medical problems and predisposition. Some common causes of a blood clot in the calf are prolonged immobilization, trauma, medications, and lifestyle choices.

It is necessary for blood to flow freely through the veins and arteries in the body for the circulatory system to function properly. A blood clot can potentially block the normal flow of blood. Consequently, clots can possibly cause severe health complications such as heart attack or stroke if they become dislodged.

One possible cause of a blood clot in the calf might be prolonged immobilization, or keeping the body still for lengthy periods of time. People who frequently embark on lengthy plane trips, are recovering from surgery or another medical procedure, or are just generally immobile run the risk of developing a blood clot due to decreased circulation. Women who are on bed rest as a result of a pregnancy are particularly at a high risk because pregnancy increases clotting factors in the blood, which can contribute to the development of clots.

Trauma can also lead to a blood clot in the calf. Whether it is the result of surgery, a fracture, or even milder wounds, anything that injures blood vessels and interferes with blood flow can potentially cause a blood clot. Some medications that cause hyper-coagulation, or increased clumping in the blood, can also increase the risk for developing a blood clot in the calf. For example, women who take hormonal birth control pills are particularly susceptible due to the decrease in blood flow caused by the medication.

Hyper-coagulation can also be caused by other factors, including heredity. Some people are simply born with a predisposition for blood clots and will develop them more easily than others, especially under the described conditions. Conversely, there are learned habits and lifestyle choices that can potentially increase the risk of developing a blood clot in the calf or elsewhere in the body. Smoking significantly increases an individual’s risk of developing a blood clot, as does harboring excessive body fat. Both of these factors impede blood flow and make veins and arteries more susceptible to clotting.