A hematoma is formed when a blood vessel ruptures due to external forces, spilling blood and accumulating in the surrounding tissue. For how long the hematoma is not absorbed, there is no clear time limit for opening, usually the hematoma can be absorbed normally without open surgery, but there are some cases that need open surgery. 1. Traumatic hematoma: subcutaneous hematoma caused by trauma can usually be absorbed by itself in 2-3 weeks, but if the hematoma is large, the absorption time may be extended accordingly, but if the patient 2. postpartum hematoma: the patient is prone to vaginal hematoma after delivery, which usually recovers in about 1 week, but if the hematoma is still not absorbed after 1 week due to its large size and serious symptoms, it may need to be treated with open drainage; 3. intracranial hematoma: for such patients, if the onset is acute, it may cause serious harm to the organism. For those who meet the indications for surgery, such as extra-membranous hematoma with a bleeding volume of more than 30 ml or sub-membranous hematoma with a bleeding volume of more than 10 ml, as well as those whose bleeding volume does not reach the standard but whose brain swelling is more serious and whose patients are already in coma and other symptoms, timely surgery is required; 4. Postoperative hematoma: hematoma is a common postoperative complication, and for superficial hematomas, local pressure bandages can be applied after surgery, which can usually be absorbed in 1-2 weeks. For hematomas that fail to be absorbed, open drainage treatment may be required at the discretion of the surgeon. For hematomas after laparotomy, smaller hematomas may resolve on their own in about 1 week, while progressively larger hematomas require surgical puncture and drainage under ultrasound guidance.