After the operation, the skin is bruised locally because the subcutaneous blood vessels are injured by external forces or rupture and bleed. Follow the doctor's advice to do postoperative care, pay more attention to rest and have a light diet. The degree and duration of swelling and bruising mostly depend on the surgical site, surgical incision type (open or closed), skin thickness, postoperative care, personal age, skin elasticity, self-healing ability and the skills and experience of doctors.