After flap surgery, if the flap is still alive after 7 days, it can be judged as having survived. Because the flap is in a stage of change within 7 days, there is always the possibility of necrosis of the flap due to vasospasm or re-occlusion of blood vessels. Therefore, 7 days after flap surgery is a dangerous period for the flap. If the flap is still alive after 7 days, it means that the flap has fully survived. However, after the flap has survived, patients are advised to protect the flap to avoid infection. Infection can also lead to necrosis of the flap, which can lead to failure of the surgery. Moreover, the flap is not wear-resistant after the operation, so it is recommended that patients must pay attention to the protection of the flap, to avoid wearing clothes or shoes, friction on the flap, resulting in necrosis of the flap.