Differential Diagnosis for Unilateral Leg Swelling in a Female

Single Most Likely Diagnosis

• Deep Vein Thrombosis (DVT): This is often the first consideration for unilateral leg swelling, especially in the absence of trauma. DVT can occur due to various factors such as immobility, surgery, pregnancy, or the use of oral contraceptives, which increase the risk of blood clot formation.

Other Likely Diagnoses

• Cellulitis: A bacterial infection of the skin and subcutaneous tissues, which can cause swelling, redness, and warmth of the affected leg.
• Lymphedema: Swelling caused by impaired lymph drainage, which can be primary (inherited) or secondary (due to surgery, infection, or trauma).
• Varicose Veins: Enlarged veins that can cause swelling, especially if there is significant venous insufficiency.
• Muscle Strain or Trauma: Direct injury to the leg can lead to swelling due to inflammation and fluid accumulation.

Do Not Miss Diagnoses

• Phlegmasia Cerulea Dolens: A severe form of DVT that causes significant swelling and cyanosis of the leg, which is a medical emergency.
• Compartment Syndrome: Increased pressure within a muscle compartment that can lead to muscle and nerve damage, requiring urgent intervention.
• Malignancy (e.g., Lymphoma or Soft Tissue Sarcoma): Although less common, malignancies can cause unilateral leg swelling and should not be overlooked.

Rare Diagnoses

• Klippel-Trenaunay Syndrome: A congenital condition characterized by vascular malformations, which can lead to leg swelling and other symptoms.
• Lipedema: A chronic condition that causes an abnormal distribution of fat in the legs, leading to swelling and pain.
• Filarial Lymphedema (Elephantiasis): Caused by parasitic infection, leading to severe lymphedema, more common in tropical regions.

Each of these diagnoses has distinct clinical features and requires specific diagnostic approaches and treatments. A thorough history, physical examination, and appropriate diagnostic tests are essential for determining the underlying cause of unilateral leg swelling in a female patient.