Bruising and swelling returning on one side 10 days after gynecomastia surgery, which includes incision and liposuction, could be due to several factors: 1. Post-Surgical Healing: It's normal to experience some fluctuation in swelling and bruising as the body continues to heal. Healing can vary between sides, and one side might take longer to resolve than the other. 2. Seroma Formation: Sometimes, fluid can accumulate under the skin, causing swelling. This can be more noticeable if it is not evenly distributed. 3. Hematoma: A localized collection of blood (hematoma) could form, leading to persistent bruising and swelling. This might be due to bleeding under the skin that continues after the initial surgery. 4. Infection: Although less common, an infection could cause increased swelling and bruising. Signs of infection include increased redness, warmth, and possibly discharge. 5. Inadequate Compression: If compression garments are not worn as directed, or if they are not fitting properly, this could lead to uneven swelling and bruising. 6. Activity Level: Engaging in physical activities or movements that stress the area too soon can exacerbate swelling or bruising. It's essential to follow up with your plastic surgeon to assess the situation. They can evaluate your condition to determine if additional treatment is necessary or if this is part of the normal healing process.