Sudden thickening of the legs is usually considered when the patient develops leg swelling, which can be of cardiac, hepatic, or renal origin, as well as due to localized causes. If there is a sudden thickening of the legs, one usually chooses to press to see if there is any edema. If there is a pit, which slowly returns to its original shape, edema is usually considered to be present, and cardiogenic, hepatic, or nephrogenic edema is most often considered to be the cause. In addition, if there is no pit when pressed down, it should be considered that there is no lymphatic obstruction, and the patient should also be considered to have edema due to thyroid problems. In addition, it is also necessary to see whether the patient’s bilateral edema is symmetrical, if only unilateral edema, i.e., unilateral leg suddenly thick, the most important thing is to be alert to the emergence of lower extremity venous thrombosis, at this time, the patient is required to do the lower extremity venous ultrasound, to see the situation of the thrombus, thrombus thrombosis should be given in a timely manner to thrombolytic therapy.