VTE is composed of deep vein thrombosis (DVT) and pulmonary embolism (PE).
A DVT is a blood clot that forms in the veins deep in your leg, usually in the calf or thigh, but can sometimes occur in other veins in your body. The blood clot blocks the flow of blood in the affected vein either partially or completely.
PE is usually the result of an underlying blood clot in the leg known as a DVT.
The clot breaks away and travels through the body, via the heart to reach the lungs. When the clot reaches the lungs, it travels through the vessels of the lung until it reaches smaller vessels where it becomes wedged. The clot may then prevent any further blood from travelling to that section of the lung. A PE is a serious, potentially life-threatening condition which requires immediate treatment.
The diagram below explains how a DVT and PE can occur