Thrombosis (Blood Clots) Symptoms & Causes

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What is a blood clot?

If your child skins his knee or scrapes his elbow, a complex series of reactions in his bloodstream initiate the formation of a blood clot, which stops the bleeding. Blood clots are a normal and healthy function of the human body that prevent blood loss in the event of injury. However, if a clot blocks the inside of a blood vessel (thrombosis), serious tissue injury can result.

  • A thrombosis may lead to loss of blood supply and severe tissue damage.
  • Left untreated, a thrombosis can cause long-term problems, such as permanent damage to the internal organs.


What are the causes of thrombosis?

One common cause of developing a pediatric thrombosis is thrombophilia, a group of disorders that increases a child’s tendency to develop excessive or dangerous blood clots in places where they shouldn’t, like the calf or lung. Thrombophilia can be thought of as the opposite of hemophilia, a disorder that prevents the blood from clotting.

There are two kinds of thrombophilia:

Inherited thrombophilia, caused by certain genetic conditions, including:

  • Factor V Leiden
  • Prothrombin gene mutation
  • Protein C, protein S or antithrombin deficiencies

Acquired thrombophilia, caused by lifestyle factors or medical conditions, including:

  • immobility
  • obesity
  • sedentary lifestyle
  • trauma

In teens and adults, risk factors also may include:

  • smoking
  • oral contraceptive use

Where does a thrombosis usually develop in children?

A thrombosis may occur anywhere in the child’s body, but most are in the calf (deep vein thrombosis, DVT) or lungs (called a pulmonary embolus). Other types of thrombosis include sinus venous thrombosis (cerebral vein clots) and arterial thrombosis.


What are the symptoms of a thrombosis?

The symptoms of blood clots in children can vary significantly depending on its size and location, and each child may experience symptoms differently.

If your child has a thrombosis in the calf, he or she may experience symptoms, such as:

  • swelling
  • pain
  • redness and warmth
  • low-grade fever

In some cases, you may even be able to feel the clot in the back of your child’s calf like a knot under the skin.

If your child has a pulmonary embolus, or thrombosis that has traveled to the lungs, he or she may experience chest pain or shortness of breath.

A pulmonary embolus is a medical emergency, and you should seek immediate medical attention if you suspect your child has a pulmonary embolus.

The symptoms of blood clots in children may resemble those of other diseases. Always consult your child’s physician for a diagnosis.

If my child has a blood clot, is he more likely to have another?

Some children are genetically predisposed to developing blood clots, a condition known as thrombophilia. Your child’s physician will determine whether the clot was caused by a type of thrombophilia or occurred for a different reason.

What are the possible complications of blood clots?

Clots can block the flow of blood, cutting off the supply of oxygen to parts of the body. Without oxygen, cells start to die, which can cause severe, permanent damage to internal organs and other body tissues. The degree of complications depends largely on the location and size of the clot.

Based on the size and location of the clot, your child’s physician will recommend a specific course of treatment to minimize complications.

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