Blood clots are easily dislodged when the thrombus is not tightly adhered to the vessel wall and when there is muscle contraction or increased abdominal pressure. In general, when a thrombus is first formed, there is no obvious fibrous tissue connecting the thrombus to the vessel wall, thus making the jelly-like thrombus easily dislodged from the vessel wall, causing pulmonary embolism. With the prolongation of time, the inflammatory response caused by the thrombus gradually encourages the proliferation of fibrous tissues, making the thrombus and the vessel wall closely connected, a process that takes about 2-3 weeks. On the basis of time judgment, the result of D-dimer test can be referred to. If the D-dimer result is low and the time is sufficient, the risk of blood clot dislodgement is generally considered to be reduced. Blood clots are easily dislodged from the vessel wall when squeezed by muscle contraction, and they can also be dislodged by the increased abdominal pressure during defecation caused by constipation. So it is important to be aware of these two points during thrombosis treatment as well.