Symptoms and diagnosis Symptoms: Pain, swelling, redness, and a feeling of warmth in the affected area, usually on one side of the body. Diagnosis: A doctor will assess your symptoms and may order a blood test or an ultrasound scan to look for a clot. Causes Prolonged immobility, such as long-distance travel or bed rest after surgery or illness, can cause blood flow to slow down, leading to clot formation. Certain medical conditions that affect blood clotting. Treatment Blood thinners: These are the most common medication to prevent the clot from growing. Thrombolytics: Stronger medications to dissolve a large clot, used in severe cases due to serious side effects. IVC filter: A device inserted into a major vein if other treatments are not an option. It can catch a large clot before it reaches the lungs. Compression stockings: These can help prevent blood from pooling in the veins. Prevention Stay active and move your legs regularly, especially during long periods of sitting. If traveling by plane, get up and walk around every hour or two for flights longer than 6-8 hours. Follow your doctor's advice on how to stay active when you have certain medical conditions that increase your risk.