If the lymph nodes are swollen, ultrasound can determine the nature of the swollen lymph nodes. Most of the swollen lymph nodes are just reactive hyperplasia and do not need to be treated. If it is accompanied by pain and redness on the surface, it is usually caused by inflammation and infection, so it is better to also do an ultrasound to see if there is lymphadenitis, etc. If the swollen lymph nodes are not painful at the same time, ultrasound is needed to determine whether the lymph nodes are benign lesions or caused by tumor metastasis. If it is caused by tumor metastasis, not only the lymph nodes are enlarged, but also the lymph node gate disappears and the shape of the lymph nodes changes, such as oval to round.