Whether or not laser treatment for hyperpigmentation caused by trauma can be done in one session is related to the depth of the hyperpigmentation. If the hyperpigmentation is light, the laser treatment can be completed in one session. If the hyperpigmentation is deep, multiple sessions are required. After the trauma, the skin scar healing or the existence of infection in the healing process leads to the appearance of hyperpigmentation usually does not appear to the body damage, but will affect the skin aesthetic, you can choose the way of laser treatment. Laser surgery to get rid of skin pigmentation is mainly through a specific wavelength, penetrate a certain deep layer of the skin, to reach the precipitation area, and break up the pigment particles. Then it is absorbed and discharged through the body’s macrophage processing, so as to achieve the effect of getting rid of hyperpigmentation. If the pigmentation is relatively mild, it can be completed in one treatment, but if the pigmentation is deeper, multiple laser treatments will be required; however, it is very rare that it can be treated in one treatment. Please consult your doctor for more information.