Acute venous embolism and thrombosis are both conditions that disrupt blood flow. Treatment may involve medications or surgery.

Blood clot formation is a protective mechanism that helps prevent excess blood loss. However, blood clots may sometimes form irregularly in the body’s blood vessels. This typically occurs in the veins, causing acute thrombosis or embolism.

This article discusses acute venous embolism and thrombosis, including the symptoms, diagnosis, and treatment methods.

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Acute thrombosis is a condition that involves the formation of a blood clot in blood vessels, partially or completely blocking blood flow. Embolism occurs when this clot travels and settles in another location, such as the pulmonary artery, which carries blood from the heart to the lungs.

Both conditions occur in veins. Doctors refer to these conditions as “venous thromboembolism.”

According to the Centers for Disease Control and Prevention (CDC), venous thromboembolism affects 900,000 people annually in the United States, causing about 60,000–100,000 deaths.

Learn more about the difference between thrombosis and embolism.

Venous thromboembolism includes both deep vein thrombosis (DVT) and pulmonary embolism. DVT causes pulmonary embolism — anyone who has DVT is at risk of developing it.

  • DVT: This results from a blood clot that forms in one of the deep leg veins. DVT commonly affects veins in the lower leg, thigh, or pelvis. Without prompt diagnosis and treatment, a clot in the deep leg veins may dislodge and travel to the lungs, where it can cause a pulmonary embolism.
  • Pulmonary embolism: This occurs when a blood clot travels through the circulatory system and blocks a blood vessel in the lungs. It is life threatening and typically requires immediate medical intervention.

The symptoms of acute venous thrombosis differ from embolism.

People with acute venous thrombosis may notice the following symptoms:

  • swelling in one leg
  • pain
  • tenderness
  • skin redness on lighter skin

Acute embolism symptoms include:

A person with these symptoms requires prompt medical evaluation and treatment.

Doctors diagnose acute venous thrombosis and embolism based on medical history, physical examination, and diagnostic test results.

Diagnostic tests for venous thrombosis typically involve radio imaging tests to check for blood clots in the leg and pulmonary veins.

The diagnostic tests for venous thrombosis include:

  • Duplex ultrasonography: This involves using sound waves to detect blood clots and blood flow patterns in the veins. It is the standard imaging test for DVT diagnosis.
  • D-dimer assay: This is a blood test that measures the blood level of D-dimer, which is a substance in the blood that is released when a clot breaks.
  • Contrast venography: This is a unique type of X-ray involving a contrast material or dye to visualize the deep leg veins. It is an invasive but accurate procedure for detecting blood clots in the deep leg veins.

Pulmonary embolism diagnostic tests are as follows:

  • Computed tomography pulmonary angiography (CTPA): This first-line diagnostic test for pulmonary embolism. It provides images of a person’s blood vessels and detects blood clots.
  • Ventilation-perfusion (V/Q) scan: This scan evaluates the degree of airflow and blood flow in the lungs.
  • Pulmonary angiography: This is a special type of X-ray that creates a video of the blood flow to the lung to aid in blood clot detection. It is an invasive procedure that involves inserting a tube into the blood vessel.

The treatment of venous thromboembolism involves the use of specific medications and, occasionally, surgery.

Medications for treating venous thromboembolism include:

  • Anticoagulants: These medications help thin the blood and prevent the formation of new blood clots.
  • Thrombolytic therapy: These medications break up already-formed blood clots in the vein or lungs.
  • Surgery: This may involve vascular procedures such as vena cava filter insertion or direct surgical removal of clots, known as thrombectomy.

Complications of venous thrombosis depend on the location and size of the blood clot.

For example, large blood clots in the lung veins may obstruct blood flow and cause lung damage.

Long-term DVT may also damage the valves in the vein, leading to post-thrombotic syndrome, which can cause swelling, pain, discoloration, and ulceration.

The outlook for acute thrombosis and embolism depends on several factors, such as the location and size of the blood clot, whether a person has other health conditions, and how quickly they receive treatment.

Generally, early diagnosis and swift medical intervention can help reduce complications and prevent organ damage.

Acute venous thrombosis and embolism are clinical conditions affecting the veins and arteries.

Acute thrombosis occurs when a blood clot forms in blood vessels and partially or completely blocks blood flow. An acute embolism occurs when a blood clot or a foreign body enters the bloodstream and obstructs blood flow.

Acute venous thrombosis typically manifests as DVT and acute embolism may present as pulmonary embolism.

Venous thromboembolism symptoms include pain in one leg, swelling, chest pain, difficulty breathing, and fainting spells.

Medications such as blood thinners can help treat these types of blood clots. In some cases, surgery may be necessary.