Swelling of the neck and back of the feet may be related to deep vein thrombosis of the lower limbs, varicose veins of the great saphenous veins, nephrotic syndrome and so on. 1. Lower extremity deep vein thrombosis: Long-term bed rest and hypercoagulability of blood can lead to lower extremity deep vein thrombosis, which will cause blood circulation obstruction and lead to swelling of neck and back of the feet. 2. Varicose saphenous vein: due to the insufficiency of saphenous vein valves, it can lead to varicose saphenous vein, and the blood will be stagnant in the vein, which will make the patient’s neck and back of the foot swollen. 3. Nephrotic syndrome: Nephrotic syndrome can be caused by infection, heredity, immunity and other factors, and can be accompanied by a large amount of proteinuria, hypoproteinemia, hyperlipidemia and other symptoms in addition to swelling of the neck and back of the feet. Swelling of the neck and back of the feet can have many reasons, it is recommended to go to the hospital in time, complete the ultrasound and other related examinations, to clarify the condition and then give appropriate treatment.