Unilateral leg swelling refers to the noticeable enlargement of only one leg. This localized swelling, known as edema, occurs when fluid accumulates in the tissues of the affected limb. While some cases are minor, it can also indicate serious conditions.
Specific Causes of Unilateral Leg Swelling
Deep Vein Thrombosis (DVT) is a cause of swelling in one leg, involving a blood clot in a deep vein. The clot can break loose and travel to the lungs, causing a pulmonary embolism. Symptoms include pain, warmth, redness or discoloration, and a heavy, aching sensation in the affected leg.
Cellulitis is a bacterial infection of the skin and underlying soft tissues. It presents with rapidly spreading redness, warmth, and tenderness in the swollen area. Individuals with compromised circulation or weakened immune systems are more susceptible to cellulitis, which can arise from minor skin breaks.
Lymphedema causes one-sided leg swelling due to impaired lymphatic system drainage. If the lymphatic system is blocked or damaged, fluid accumulates. It develops after certain surgeries, cancer treatments, infections, or injuries affecting lymph nodes, causing persistent swelling, tightness, and thickened skin.
Venous insufficiency occurs when valves within leg veins do not function correctly. This allows blood to pool in the leg instead of returning to the heart. It leads to swelling, aching, a heavy feeling, and sometimes varicose veins, worsening after prolonged standing.
Injury or trauma to the leg causes swelling. Sprains, fractures, muscle tears, or severe blunt trauma can cause swelling in the injured area. Swelling is often accompanied by pain and may hinder weight-bearing.
A Baker’s cyst is a fluid-filled sac that forms behind the knee. If this cyst ruptures, it releases fluid into the calf, causing sudden sharp pain and swelling in the lower leg. Symptoms of a ruptured Baker’s cyst can mimic those of a DVT.
Tumors or cysts can cause unilateral leg swelling by compressing blood vessels or lymphatic channels. This obstructs fluid flow, causing swelling. For example, enlarged lymph nodes can exert pressure on veins, resulting in one-sided leg edema.
When to Seek Immediate Medical Care
Seek immediate medical attention if leg swelling appears suddenly and affects only one leg. If accompanied by pain, redness, or warmth, this could indicate a deep vein thrombosis (DVT).
Swelling with chest pain, shortness of breath, or dizziness warrants emergency care, as these symptoms signal a pulmonary embolism, a complication of DVT. A rapid heart rate or coughing up blood also indicates a medical emergency.
Rapidly spreading redness, warmth, or a fever can suggest a severe infection like cellulitis, requiring urgent antibiotic treatment. Any swelling after a significant injury that prevents weight-bearing also needs prompt medical assessment.
Diagnostic Approaches and Treatment Options
When a person seeks medical attention for unilateral leg swelling, the diagnostic process begins with a thorough medical history and physical examination. The doctor will inquire about the swelling’s onset, duration, and associated symptoms, as well as relevant medical conditions or recent events. A physical examination assesses the swelling’s characteristics, including temperature, color, and tenderness.
Imaging tests identify the underlying cause. A duplex ultrasound visualizes blood flow in veins and can detect blood clots or vein valve issues. X-rays, MRI, or CT scans may be performed for bone concerns or complex cases. Blood tests check for signs of infection, inflammation, or other systemic conditions.
Treatment for unilateral leg swelling addresses the identified underlying cause. If DVT is diagnosed, anticoagulant medications are prescribed to prevent clot growth and reduce pulmonary embolism risk. Bacterial infections like cellulitis are treated with antibiotics.
Symptomatic relief measures include elevating the affected leg to reduce fluid and using compression stockings to improve blood flow and minimize swelling. Pain management strategies are also employed. For lymphedema, specialized therapies like manual lymphatic drainage and compression garments are used, sometimes with physical therapy. Regular movement and avoiding prolonged sitting or standing can help manage and prevent future swelling.