A Guide to Superior Vena Cava Syndrome

Medically Reviewed By Megan Soliman, MD
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The superior vena cava returns blood from the upper body to the heart. Superior vena cava syndrome occurs when there’s an obstruction of this blood flow. A blood clot or tumor within the blood vessel wall can cause obstruction. Various treatments are available depending on the cause.

This article explains what superior vena cava syndrome is and how doctors diagnose and treat it.

What is superior vena cava syndrome?

Person experiencing dizziness and headache
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Superior vena cava syndrome happens when there’s an obstruction of blood flow through the superior vena cava. The superior vena cava is a large vein that returns blood to the heart from the neck, head, upper extremities, and torso. A blood clot or tumor within the blood vessel wall can cause obstruction.

This syndrome is often seen alongside cancer, but there are cases of noncancerous causes. The condition is rare in children, but if it does occur, it’s often a medical emergency due to swelling that blocks the trachea.

In adults, severity depends on how quickly the superior vena cava becomes blocked. Each year, there are an estimated 15,000 cases of superior vena cava syndrome in the United States.

What are the symptoms of superior vena cava syndrome?

Symptoms of this condition can develop suddenly or gradually, depending on how quickly the superior vena cava becomes blocked. Common symptoms include:

In rare cases, Horner’s syndrome can occur. This condition presents as a small pupil and drooping eyelid on one side of the face.

What causes superior vena cava syndrome?

The most common cause of superior vena cava syndrome is cancer, particularly small cell bronchogenic carcinoma, also known as small cell lung cancer.

The second most common cancer that causes superior vena cava syndrome is non-Hodgkin lymphoma, followed by metastatic tumors.

Noncancerous causes of superior vena cava syndrome comprise 40% of cases. They are associated with blood clots from catheters or pacemaker wires.

Rare causes of superior vena cava syndrome include:

Who is at risk of superior vena cava syndrome?

People with lung cancer or non-Hodgkin lymphoma are more likely than those with other types of cancer to develop superior vena cava syndrome. However, not everyone with these types of cancers will develop the condition.

Having an implanted medical device, such as a pacemaker, also increases your risk because of the chance of developing a blood clot.

How do doctors diagnose vena cava syndrome?

Initial evaluation for superior vena cava syndrome will include a chest X-ray to look for masses. A CT scan of the chest is also helpful in identifying masses or blood clots.

If your doctor suspects small cell lung cancer, they will collect a sputum sample. If the sputum sample is negative for cancer, they will take a biopsy from an accessible site and test it for cancer.

What are the treatments for superior vena cava syndrome?

Treatment for superior vena cava syndrome depends on the site of the obstruction and the severity of symptoms. People with sufficient blood flow and minimal symptoms may not need treatment.

In people with symptoms, medical management can include:

  • keeping the head elevated
  • taking corticosteroids to reduce swelling
  • taking diuretics to remove excess fluids
  • using a bronchodilator to widen airways
  • using oxygen therapy

If a cancerous tumor is causing the syndrome, treatment will involve chemotherapy, radiation, or both to treat the cancer. Rapid treatment with chemotherapy has been shown to result in complete or partial response rates of superior vena cava syndrome in 80% of people with small cell lung cancer, reports the National Cancer Institute.

When a blood clot is causing superior vena cava syndrome, doctors will remove the blood clot with surgery or medications that break up the clot.

Procedures to open the superior vena cava include:

  • an intravascular stent
  • a surgical bypass for larger noncancerous obstructions

What are the potential complications of superior vena cava syndrome?

Potential complications of superior vena cava syndrome include:

  • cerebral edema, or brain swelling
  • laryngeal edema, or swelling of the larynx
  • pulmonary embolism, if a blood clot is present
  • compromised upper respiratory tract


Superior vena cava syndrome is a set of symptoms that occur when there’s a blockage in the superior vena cava. A blockage is commonly due to a cancerous tumor but can also be from a blood clot.

This syndrome is most common in adults. It rarely occurs in children. People with lung cancer have a higher risk of developing superior vena cava syndrome.

Treatment aims at treating the cancer, blood clot, or other condition causing the blockage. People with no symptoms may not need treatment.

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Medical Reviewer: Megan Soliman, MD
Last Review Date: 2022 Oct 28
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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