What are the possible causes of left arm swelling?

Left Arm Swelling: Causes and Diagnostic Approach

Left arm swelling most commonly results from upper extremity deep vein thrombosis (UEDVT), which accounts for up to 10% of all DVTs and requires urgent duplex ultrasound evaluation, as unilateral swelling indicates an obstructive process at the level of the brachiocephalic, subclavian, or axillary veins. 1, 2

Critical Immediate Causes Requiring Urgent Evaluation

Upper Extremity Deep Vein Thrombosis (UEDVT)

• UEDVT is the most important diagnosis to exclude urgently, as it can lead to pulmonary embolism in up to 36% of cases 2
• Presents with ipsilateral upper-extremity edema, pain, paresthesia, and prominent superficial veins serving as collaterals around the obstruction 1, 3
• Unilateral swelling specifically indicates obstruction at the brachiocephalic, subclavian, or axillary vein level 1, 2, 3

High-Risk Factors for UEDVT

• Indwelling venous devices (catheters, pacemakers, defibrillators) are the highest risk factor for thrombus formation 1, 4
• Advanced age, previous thrombophlebitis, postoperative state, hypercoagulability, heart failure, cancer, intensive care unit admissions, and trauma 1
• Dialysis access (AV fistula or graft) is a high-risk feature 3
• Vigorous repetitive movements with anatomic abnormalities (Paget-Schroetter syndrome/effort thrombosis) 5

Diagnostic Algorithm

First-Line Imaging

• Duplex ultrasound is the initial diagnostic test of choice, with sensitivity and specificity above 80% for UEDVT 2, 3
• Grayscale imaging directly visualizes echogenic thrombus and assesses vein compressibility—lack of compression indicates acute or chronic thrombus 3
• Doppler assessment evaluates blood flow patterns, cardiac pulsatility, and respiratory variation, with dampening indicating central venous obstruction 3
• Test for central vein collapse with rapid inspiration ("sniffing maneuver")—impaired collapse suggests central obstructive process 3

Advanced Imaging When Ultrasound Inadequate

• Venography or CT venography is required when central venous stenosis is suspected and ultrasound cannot adequately visualize thoracic vessels 2, 3, 4
• CTV with IV contrast in neutral and elevated arm positions demonstrates venous thrombosis and collateral circulation 3
• Venous ultrasound may be falsely normal in subclavian thrombosis, particularly with pacemakers—venogram is usually required for definitive diagnosis 4

Other Important Causes of Left Arm Swelling

Central Venous Stenosis

• Ipsilateral extremity swelling without other cause suggests central venous stenosis, particularly in patients with dialysis access 3
• Venous hypertension from downstream stenosis forces blood flow through venous collaterals, producing chronic venostasis that can progress to skin ulceration if untreated 3
• Swelling persisting beyond 2-6 weeks after dialysis access placement requires venography or other noncontrast study 3

Lymphedema

• Results from lymphatic obstruction due to malignancy, surgery (particularly breast cancer treatment), or radiation 1, 6
• Chronic arm edema following breast cancer treatment develops months or years later due to damaged axillary lymph drainage routes 6
• Requires referral to a therapist knowledgeable about lymphedema diagnosis and treatment 2

Increased Capillary Hydrostatic Pressure

• Superior vena cava syndrome, reflex sympathetic dystrophy, or trauma 1
• Malignancy causing compression (adenocarcinoma can present with unilateral upper extremity edema from lymphatic or venous obstruction) 7

Infection and Inflammation

• Arm edema is commonly mistaken for cellulitis, causing delay in diagnosis of subclavian thrombosis 4
• Allergic reactions, infection, or inflammatory arthritis increase capillary permeability 1

Trauma-Related Causes

• Hematoma formation manifests with obvious discoloration and swelling 3
• Infiltration of veins during cannulation causes swelling, bruising, and pain 3
• Arteriovenous fistulas (rare with blunt trauma) 8

Common Pitfalls to Avoid

• Do not dismiss unilateral swelling as benign or treat empirically as cellulitis—this presentation demands urgent evaluation for venous obstruction 3, 4
• Do not rely solely on screening venous ultrasound in patients with pacemakers—subclavian thrombosis should be considered even with normal ultrasound, and venogram may be required 4
• Recognize that catheter-associated UEDVT may be asymptomatic initially, manifesting only as catheter dysfunction before progressing to overt swelling 1, 3
• DVT limited to the brachial veins need not be associated with swelling—obstruction must be at axillary or more proximal level 1

Immediate Management When UEDVT Confirmed

• Initiate therapeutic anticoagulation immediately following standard DVT treatment protocols, with minimum duration of 3 months for UEDVT involving axillary or more proximal veins 2, 3
• Use compression bandages or sleeves for persistent swelling and discomfort 3
• Investigate lower extremities if no local cause identified, as correlation between upper and lower extremity DVT exists 3

Follow-Up Protocol

• Reassess within 48-72 hours to evaluate response to initial management and ensure no progression of symptoms 2, 3
• Schedule formal evaluation at 6 weeks if edema persists to detect delayed complications or underlying pathology 2, 3