If the swelling of the left foot alone occurs, it is necessary to exclude any recent trauma, and if trauma is excluded, it is necessary to see whether there is any abnormality in the skin temperature of both limbs and whether there is any abnormality in the pulsation of the distal arteries. If the difference in skin temperature between the two sides is particularly large, for example, if the skin temperature of the left foot swelling is reduced and the arterial pulsation is weakened, it may be a lesion of the arteries of the lower extremity. If intermittent claudication occurs during normal walking, that is, swollen and painful feet after walking for a period of time, lower extremity artery occlusion or severe stenosis is also considered. In addition, another condition is venous lesion of the lower extremity, that is, swelling of the left side of the foot due to poor vascular reflux in the lower extremity, and in these cases it is recommended to improve the arteriovenous ultrasound examination of the lower extremity. There are some uncommon cases of idiopathic lower limb edema in women, which can be observed regularly if there is no obvious cause after completing relevant examinations.