A three-year-old child who fell on the back of the head with a bag can first apply cold compresses, and then take the child to the hospital to rule out intracranial injury. The child fell on the back of the head bag, most of the scalp capillary rupture bleeding, the formation of subcutaneous hematoma, you can first cold compress (within the first 72 hours), to reduce the symptoms of swelling and pain. At the same time, take your child to the hospital to determine whether there is any intracranial injury by doing a cranial CT examination. If the hematoma is only subcutaneous, most of it can be absorbed on its own. If the hematoma is still not absorbed after a week, especially if it is large, a syringe can be used to puncture and aspirate it. If there is a combination of intracranial injury, such as brain hemorrhage, depending on the amount of bleeding, choose to hospitalize conservative treatment or surgical treatment. If your child has a bump on the back of the head from a fall, try to take him or her to the hospital and treat him or her according to his or her condition.