Scalp hematoma is mostly caused by blunt force injury to the scalp, and can be divided according to the relationship between the layers of the scalp: 1. Subcutaneous hematoma: Because of the close connection between the subcutaneous tissue layer and the skin layer and the capillary tendon layer, the hematoma in this layer is not easy to spread and is small in size. The tissue around the hematoma is swollen and thickened, and there is a sense of depression when touched, so it is easily misdiagnosed as depressed skull fracture, and sometimes cranial X-ray examination is required to exclude the possibility of fracture. 2. Subcapsular hematoma: caused by rupture of small artery or conduction vessel. Because of the loose tissue of the subcapsular tendon membrane, blood can easily expand in all directions, and blood can fill the whole subcapsular tendon membrane, making the head significantly larger, and its blood content can reach hundreds of milliliters. 3, subperiosteal hematoma: mostly seen after obvious deformation of the skull during blunt injury, such as birth injuries in newborn infants, infant and child ping-pong ball depression-like skull fractures, and after linear fractures of the skull in adults. The hematoma often does not extend beyond the cranial suture because the periosteum is firmly attached at the cranial suture. In infants, the periphery and periosteum of the old hematoma may thicken or ossify, and even form a bony cyst containing old blood. Treatment: Smaller scalp hematomas tend to absorb on their own, while larger ones often require multiple punctures to remove them, or silicone tubes inserted into the hematoma cavity to drain them, along with local pressure bandaging. For subcapsular hematomas that do not respond to the above treatment and continue to increase in size, the scalp can be incised to stop the bleeding and remove the hematoma. In subperiosteal hematomas with combined skull fractures, attention should be paid to the possibility of complicating intracranial hematomas. In cases where the periosteum is cranially tough or ossified, the top of the raised periosteum is removed. Any hematoma that has become infected requires incision and drainage.