A blood clot forms when blood cells and proteins thicken into a semi-solid mass inside a vessel. While most people associate these clots with the legs, they can also occur in the upper body, specifically in the arm. This condition, called Upper Extremity Deep Vein Thrombosis (UEDVT), is less common than its counterpart in the lower limbs, making up about 5% to 10% of all deep vein thrombosis cases. Recognizing this possibility and its distinct features is important because, like any deep vein clot, an arm clot carries the risk of serious complications if not addressed promptly.
Understanding Upper Extremity Thrombosis
Upper Extremity Deep Vein Thrombosis involves the formation of a clot within one of the deeper veins in the arm, shoulder, or neck. These deep veins include the subclavian, axillary, and brachiocephalic veins, which are responsible for returning deoxygenated blood toward the heart. The presence of a thrombus obstructs normal blood flow, leading to congestion in the limb.
UEDVT is distinct from a superficial clot, which forms in a vein closer to the skin’s surface and is generally considered less severe. However, a deep vein clot in the arm can pose a serious threat due to its proximity to the chest and major vessels. The location of the clot determines the severity of the symptoms and the risk of the clot traveling toward the lungs.
Identifying the Warning Signs
The physical manifestations of an arm clot often begin with swelling, known as edema, that affects the arm, hand, or fingers. This swelling may be accompanied by a feeling of heaviness or fullness in the limb, which can limit movement and cause discomfort. The degree of swelling can vary, sometimes becoming quite noticeable when compared to the unaffected arm.
Pain or tenderness is another common symptom, typically localized in the arm, shoulder, or neck region. The skin over the affected area may also show noticeable changes, including warmth to the touch and discoloration, appearing unusually red, purple, or bluish (cyanosis). These signs reflect the back-up of blood flow caused by the blockage.
In some instances, the symptoms can be subtle or even absent. However, certain signs require immediate medical attention as they may indicate a serious complication, such as a pulmonary embolism (PE). These complications occur if a piece of the clot breaks off and travels to the lungs.
Signs of a possible PE include the sudden onset of shortness of breath, chest pain that may worsen with a deep breath, and light-headedness or dizziness. If these symptoms occur alongside arm discomfort, it is a medical emergency requiring immediate contact with emergency services.
Key Causes and Risk Factors
The development of UEDVT is typically categorized into secondary causes, which are the most frequent, and primary causes. The majority of arm clots are secondary, meaning they are provoked by external factors, particularly medical procedures. The increasing use of central venous catheters (CVCs), peripherally inserted central catheters (PICCs), and pacemakers significantly raises the risk.
These devices can mechanically damage the inner lining of the vein during insertion or irritate the vessel wall over time, triggering the clotting process. Cancer is also a major secondary risk factor, as the disease itself and its treatments can increase the blood’s tendency to clot. Trauma to the arm or shoulder, such as a fracture or severe muscle injury, can also precipitate clot formation.
Primary UEDVT
Primary UEDVT occurs less often and is generally associated with anatomical factors or strenuous physical activity. Effort thrombosis, also known as Paget-Schroetter Syndrome, typically affects young, otherwise healthy individuals, often athletes involved in repetitive overhead arm motions. The repeated physical stress causes microtrauma to the axillary or subclavian veins.
This microtrauma, combined with possible compression of the vein by nearby structures, such as a cervical rib or tight muscles, leads to clot formation. General health conditions, including inherited clotting disorders (thrombophilias) or periods of prolonged immobility, also increase the likelihood of developing an arm clot.
Necessary Action and Treatment
If an arm clot is suspected based on swelling, pain, or discoloration, seeking immediate medical evaluation is necessary. Diagnosis typically begins with a physical examination and is confirmed through imaging tests, most commonly a duplex ultrasound, which uses sound waves to visualize blood flow and identify the clot. In some cases, a blood test for D-dimer may be used to assess the likelihood of a clot being present.
The standard medical treatment for UEDVT involves the use of anticoagulant medications, commonly called blood thinners. These medications do not dissolve the existing clot but work to prevent it from growing larger and reduce the risk of a part of it breaking off to cause a pulmonary embolism. Anticoagulation also allows the body time to naturally break down the clot.
Treatment generally lasts for a minimum of three months, though the exact duration depends on the cause of the clot. If the clot is related to a functional catheter, the catheter may be left in place while the patient receives anticoagulation therapy. In select cases, other procedures may be used to remove or dissolve the clot, but anticoagulation remains the mainstay of initial treatment.