Clots occur in veins when there is altered flow, damage to the vein wall, abnormalities of the blood’s clotting factors, or a combination of the three. Clots that occur in the large veins connected directly to the heart are called deep venous thrombosis (DVT).

Signs and symptoms

Symptoms can progress over a day or several days and may include:

  • Pain and swelling of the affected limb
  • Skin that turns red or purple


Ultrasound is the first tool used to determine the location and extent of the affected veins. Additional imaging may be needed to identify the extent of the clot or the reasons for the clot.


Anticoagulation (blood thinners) is the first-line therapy for treating clots. If the clot is extensive and symptomatic, it is treated with thrombolysis (dissolution) or thrombectomy (removal).

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