Clotting Problems

Approved by the Cancer.Net Editorial Board, 06/2018

A blood clot is a serious condition that needs immediate treatment. People with cancer and those receiving cancer treatment have an increased risk for blood clots.

Normal blood clotting, called coagulation, is a complex process. It involves specialized blood cells, called platelets, and different proteins in the blood, called clotting or coagulation factors. These platelets and coagulation factors clump together to heal broken blood vessels and control bleeding. Coagulation factors that promote bleeding and those that promote clotting must be balanced.

Blood clotting disorders occur when some clotting factors are missing or damaged. This causes clots to form inside the body that block normal blood flow and cause serious problems.

Blood clots can occur in and travel to different parts of the body, including:

  • Veins, called a deep venous thrombosis

  • The lungs, called a pulmonary embolism

  • An artery (less common but also very serious)

Signs and symptoms of clotting problems

People with clotting problems may experience:

  • Arm or leg swelling on 1 side of the body

  • Pain in the arm or leg where a blood clot is located

  • Trouble breathing or chest pain when breathing

  • Rapid heart beat

  • Low oxygen levels

Relieving side effects is an important part of cancer care and treatment. This is called palliative care or supportive care. Tell your health care team about any of these symptoms immediately. Even people with low levels of platelets can develop a blood clot. Sometimes people do not know they have a blood clot until it is diagnosed during a test.

Causes of clotting problems

People with cancer have a higher risk of blood clots and clotting disorders. This may be caused by the cancer or the treatment, such as:

  • Chemotherapy

  • Surgery

  • Medications called steroids

  • Long-term use of a catheter

Long periods of inactivity, such as a long plane or car ride, can also increase the risk of a blood clot.

Diagnosing clotting problems

Your doctor may use one or more techniques to diagnose a blood clot:

  • A Doppler ultrasound. An ultrasound uses sound waves to look at the flow of blood in veins in the arms or legs. It can detect decreased blood flow from a blood clot.

    A computed tomography (CT) scan. A CT scan takes pictures of the inside of the body using x-rays taken from different angles. A special dye called a contrast medium is injected into a patient’s vein or given as a pill or liquid to swallow before the scan to provide better detail on the image. Doctors commonly use CT scans to diagnose a blood clot in the lungs or PE.

  • A lung ventilation/perfusion (VQ). This test that can diagnose a pulmonary embolism is made up of 2 different parts:

    • A ventilation scan of the airflow in the lungs

    • A perfusion scan of the blood flow in the lungs

  • An angiogram. This test can detect a blood clot in an artery. During an angiogram, a dye is injected into the artery. And then the artery is examined with a special x-ray device called a fluoroscope

Managing clotting problems

A person with a blood clot needs immediate treatment. The most common treatment is blood thinners injected either under the skin or into a vein. Once the blood is considered thin enough, there is no longer a risk of clotting. At this point, some people can begin taking a blood thinner pill that is swallowed.

People who are receiving blood thinners must be regularly monitored for any increased bleeding. Some people are unable to receive blood thinners because they have low platelet levels or a high risk of bleeding. For these people, a special type of filter can be placed in the body to prevent a blood clot from traveling to the lungs, a condition that can be very dangerous.

More Information

When to Call the Doctor During Cancer Treatment

Traveling with Cancer