SVC obstruction is a narrowing or blockage of the superior vena cava (SVC), which is the second largest vein in the human body. The superior vena cava moves blood from the upper parts of the body to the heart.

Superior vena cava obstruction; Superior vena cava syndrome

SVC obstruction is a rare condition.

It is most often caused by cancer or a tumor in the mediastinum (the area of the chest under the breastbone and between the lungs).

Types of cancer that can lead to this condition include:

• Breast cancer
• Lung cancer
• Lymphoma
• Metastatic cancer to the lung (cancer that has spread to the lungs)
• Testicular cancer
• Thyroid cancer
• Thymus tumor

SVC obstruction can also be caused by noncancerous conditions that cause scarring near the SVC. These conditions include:

• Histoplasmosis (a type of fungal infection)
• Inflammation of a vein (thrombophlebitis)
• Lung infections (such as tuberculosis)

Other causes of SVC obstruction include:

• Widening of the artery that leaves the heart (aortic aneurysm)
• Blood clots in the SVC
• Tightening of the thin lining of the heart (constrictive pericarditis)
• Effects of radiation therapy for certain medical conditions
• Enlargement of the thyroid gland (goiter)

Catheters placed in the large veins of the upper arm and neck may cause blood clots in the SVC.

Symptoms occur when something blocks the blood flowing back to the heart. Symptoms may begin suddenly or gradually, and may worsen when you bend over or lie down.

Early signs include:

• Swelling around the eyes
• Swelling of the face
• Swelling of the whites of the eyes
• Distended veins in the neck

The swelling may be worse or more prominent when lying down than when upright. It may be worse in the early morning hours and may go away by mid-morning.

The most common symptoms are shortness of breath (dyspnea) and swelling of the face, neck, trunk, and arms.

Other possible symptoms include:

• Decreased alertness
• Dizziness, fainting
• Headache
• Reddish face or cheeks
• Reddish palms
• Reddish mucous membranes (inside the nose, mouth, and other places)
• Redness changing to blueness later
• Sensation of head or ear fullness
• Vision changes

The goal of treatment is to relieve the blockage.

Diuretics (water pills) or steroids (anti-inflammatory medicines) may be used to temporarily relieve swelling.

Other treatment options may include radiation therapy or chemotherapy to shrink the tumor, or surgery to remove the tumors. Surgery to bypass the obstruction is rarely performed. Placement of a stent (tube placed inside a blood vessel) to open up the SVC may be performed.

The outcome varies, depending on the cause and the amount of blockage.

SVC obstruction caused by a tumor is a sign that the tumor has spread, and it indicates a poorer long-term outlook.

The throat could become blocked, which can block the airways.

Increased pressure may develop in the brain, leading to changed levels of consciousness, nausea, vomiting, or vision changes.

Contact your provider if you develop symptoms of SVC obstruction. Complications are serious and can sometimes be fatal.

Prompt treatment of other medical disorders may reduce the risk of developing SVC obstruction.

Published Date: February 13, 2025
Published By: Jacob Berman, MD, MPH, Clinical Assistant Professor of Medicine, Division of General Internal Medicine, University of Washington School of Medicine, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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