Paget-Schroetter syndrome (PSS) is a rare blood clotting syndrome that affects the blood vessels in the upper arms. It’s more common in young athletes who use upward repetitive arm motions, such as weightlifters or wrestlers.

PSS is a rare kind of deep vein thrombosis (DVT). DVT is when a blood clot forms in a deep vein. In particular, PSS is DVT of the upper extremities, specifically the axillary and subclavian veins in the arms.

The syndrome is rare, with an incidence rate of about 1 to 2 people per 100,000, and it’s most common among people in their 20s or 30s who have no other health issues.

Sometimes PSS doesn’t have any symptoms. But when it does, it might affect how you feel or how your arm looks.

Symptoms of PSS include:

  • pain in your arm, neck, or shoulder
  • swelling in your arm
  • changes in skin color on your arm
  • tenderness in your arm
  • veins you can see or feel

Feelings of a dull ache in the shoulder or swelling in the hand can also be symptoms of the syndrome.

Some people call PSS “effort thrombosis,” as it usually happens after repeated upward motions of the arms, such as during weightlifting, swimming, pitching, and wrestling. That said, it can also occur in people who don’t engage in these types of activities. Thrombosis is another word for blood clot formation.

Along with upward motions, the thrombosis results from compression of the area around the subclavian vein. The subclavian vein carries blood from the upper body back to the heart. Over time, this compression damages the vein’s lining. Additionally, muscle growth in that area can reduce the amount of room for the vein.

PSS is a type of thoracic outlet syndrome, a group of conditions where there’s compression of a blood vessel or nerve between the collarbone and top rib.

Some risk factors for PSS include:

  • being in your 20s or 30s and having no other risk factors for blood clotting
  • having a cervical rib or “neck rib”
  • having lateral insertion of the costoclavicular ligament, a ligament that connects the collarbone to the first rib

A “neck rib” is an overdevelopment of the spine that usually goes unnoticed and typically doesn’t cause medical problems. The costoclavicular ligament helps stabilize a shoulder joint, and “lateral insertion” refers to how the ligament sits in the body.

PSS is twice as common in males than females, and it typically happens in the shoulder of the dominant arm.

Doctors usually diagnose PSS using imaging tests. The first step is an ultrasound of the upper arms and shoulders. It’s not always possible to see all the veins using an ultrasound, so a doctor might perform other imaging tests using CT or magnetic venography.

They might also order blood tests to look for evidence of thrombophilia, a condition that makes it more likely that your blood will form clots.

If you have signs of a pulmonary embolism (PE), which is when a blood clot breaks loose from a vein and travels to the lungs, a doctor might order further testing. Symptoms of PE include shortness of breath, chest pain, and dizziness.

The first-line treatment for PSS is anticoagulant therapy. A doctor might administer a blood-thinning medication like heparin into your vein.

If it’s been less than 2 weeks since your symptoms started, a doctor might also try catheter-directed thrombolysis. In this procedure, a healthcare professional will place a thin tube into your vein and pass a clot-breaking medication through the tube.

A doctor might also recommend surgery to relieve the compression of the vein. The type of surgery you need will depend on what’s putting pressure on the area. But options include:

  • removing all or part of the rib
  • removing part of the surrounding muscle
  • removing part of the costoclavicular ligament
  • breaking up of scar tissue around the vein

Another possible option is to insert a stent into the vein to keep it open, but surgery is a more permanent treatment for PSS.

People can recover after experiencing PSS.

A 2021 review of studies listed outcome rates of different treatments for PSS. Across 25 studies involving 1,511 people, thrombolysis resolved the clot in 78% of those who had this procedure. Anticoagulation therapy got rid of the clot in just over 40% of people.

The review noted that there’s not enough data that compares thrombolysis, anticoagulant therapy, and decompression surgery.

PSS is a type of thoracic outlet syndrome. It’s when a blood clot forms in one of the deep veins in the upper body.

It’s most common among younger people with no other health issues. A primary cause is repetitive upward movements of the arms.

Treatment involves blood-thinning medications and thrombolysis to get rid of the clot and decompression surgery to relieve pressure on the vein.