The bulge above the incision after thyroid surgery may be caused by hematoma, inflammation and infection, scar hyperplasia and so on. 1. hematoma: if the wound is not closed well after thyroid surgery due to loose sutures, it will cause blood seepage from the wound to form a hematoma, which can be manifested as a bulge above the incision. 2. Inflammation and infection: If the incision is infected with staphylococcus and other pathogens after thyroid surgery, it will lead to localized swelling and pus, which can cause bulge above the incision. 3. Scar hyperplasia: Abnormalities in the repair process of the post-thyroid surgery incision can lead to overgrowth of tissues and the formation of a bulge. It is recommended to go to the hospital in time to clarify the cause of the bulge above the incision after thyroid surgery. If treatment is needed, standardized treatment should be carried out under the guidance of the doctor.