What’s a blood clot?

When you get cut, components of your blood clump together to form a clot. This stops the bleeding. Sometimes blood inside your veins or arteries can form a semisolid lump and cause a clot that serves no purpose. This can be damaging.

If you get a clot in the veins deep in your body, it’s called deep vein thrombosis (DVT). If you get a clot in the veins near the surface of the skin with inflammation, it’s called superficial thrombophlebitis. Clots that dislodge and travel to other locations in the body are called emboli.

DVT usually occurs in veins of the legs, but it can develop in your arms, too. When it happens in the arms, it’s called DVT of the upper extremities (DVT-UE). Of all DVT cases, 4 to 10 percent are DVT-UE, according to a 2017 systematic review.

As many as 60 percent of people with a blood clot in a deep vein of the arm may experience no symptoms at all, according to the same 2017 review. Symptoms may also come on gradually.

You may notice some or all of these in your arm:

  • swelling, usually in one arm
  • cramping-type pain
  • tenderness to the touch
  • reddish or bluish tone to the skin
  • warm to the touch

If you’re experiencing any of these symptoms, seek immediate medical attention.

Blood clots form when blood cells called platelets and various proteins cause your blood to coagulate into a semisolid mass. Blood clots in the arms are classified as primary or secondary, depending on what caused your blood to clot.

Primary DVT-UE is rare. It can be either due to effort thrombosis, also called Paget-Schroetter syndrome, or it can be idiopathic. This means there’s no obvious cause or trigger. People with effort thrombosis develop a clot — usually in their dominant arm — after a strenuous activity like rowing, wrestling, weight lifting, or baseball pitching.

Secondary DVT-UEs make up 80 percent of cases. These happen when something disrupts the vein, initiating the clot.

These triggers can include:

  • central venous catheters
  • pacemakers
  • tumors

Blood clots in the arm have become more common because of the increased placement of medical implements in the veins. More than half of people with DVT-UE have a cardiac pacemaker or central venous catheter in the area of the clot. Up to one-fourth of people with a central venous catheter will develop a clot, according to a 2002 review.

The second most frequent risk factor for blood clots in the arm is cancer. Up to 49 percent of people with DVT-UE have a tumor.

Surgery is another risk factor for blood clots. As many as 54 percent of people with these blood clots developed them postoperatively.

Other factors that can increase your risk of a blood clot in your arms are:

  • being over 40 years old
  • not being able to move much
  • smoking
  • a history of other blood clots

If you’ve had surgery, a central line implanted, or a pacemaker put in, your healthcare team will be watching for signs of blood clots. They’ll be able to diagnose and treat you quickly. If you’re home and notice any symptoms of a blood clot, make an appointment with your doctor.

Your doctor will start with a physical exam and ask you a series of questions about when symptoms started, what you were doing before they started, and other symptoms you may have. Then you’ll probably take an imaging test.

An ultrasound is the fastest, easiest, and least expensive way to look for a blood clot in your arm. In this test, sound waves penetrate your skin and create a view of your veins.

Other imaging tests that your doctor may use to make a diagnosis or to help guide treatment include:

  • CT scan. This imaging test may be used to rule out blood clots in parts of your body other than your arm. It uses computers and X-rays to take cross-sectional images of your body.
  • MRI scan. An MRI uses radio waves and magnets to take images of your body. This test can be used to see your veins.
  • Contrast venography. For this procedure, a contrast dye is injected, and then X-rays are used to see your veins.

If you receive a diagnosis of a deep vein clot in your arm, the primary treatment goals will be to stop growth of the clot, relieve your symptoms, and prevent the clot from moving to your lungs or other parts of your body where it can cause damage.

This will be done with the following:

  • Limb elevation. This will help reduce swelling and ease pain.
  • Graduated compression arm sleeve. This is like a tight sock for your arm. It increases blood flow from the hand back toward the heart.
  • Blood-thinning medications. Although these medications don’t actually “thin” the blood, they do slow the formation of new clots and keep existing clots from getting bigger.

If these treatments don’t solve the problem or if your clot is very large, your doctor may recommend clot removal. The blood clot can be broken up by injecting medication into the problem vein, or it can be surgically broken up and removed.

Once initial treatment is complete, you’ll probably continue maintenance therapy. This can last from a minimum of 3 to 6 months to the long term, depending on the situation. Staying on blood thinners and wearing your compression sleeve will help keep your existing clot from growing. It will also prevent new clots from forming.

The most dangerous complication of a DVT in your arm is if a piece of the clot breaks off and travels to your lung, forming a pulmonary embolism. Up to one-third of people with DVT-UE will have a pulmonary embolism. This is an emergency and can be deadly. If you have sudden shortness of breath and a sharp, stabbing pain in your chest, seek immediate medical attention.

Post-thrombotic syndrome may occur if the valves inside the clotted vein are damaged and cause high blood pressure in that vein. Symptoms vary from mild fluid retention with little discomfort to debilitating limb swelling with pain and formation of skin ulcers. Following your treatment plan — including taking medications and wearing compression sleeves — can prevent or limit post-thrombotic syndrome.

If you stick with your treatment plan, your overall outlook after a blood clot in your arm is good. But they’re known to recur, especially if you need to keep your central venous catheter for ongoing treatments. If you begin experiencing any unusual symptoms, see your doctor.

There are several practical steps you can take to prevent blood clots from forming in your arms:

  • If you’re admitted to the hospital, ask your doctor whether you need blood thinners and compression garments (hose for the legs and sleeves for the arms).
  • If you need a central venous catheter or pacemaker, ask your doctor about preventing blood clots.
  • Stay active and exercise.
  • Maintain a healthy weight.
  • Don’t sit still for too long. Move your feet, ankles, hands, wrists, and arms to keep your blood flowing.
  • Get regular checkups to look for and treat heart disease, diabetes, and cancer.