Seroma, also known as serous fluid, is a common postoperative condition that occurs when fluid accumulates in the body's tissues where a surgical procedure has taken place. While the term seroma is commonly used, there are other synonyms that describe this condition, including hygroma, lymphocele, and pseudocyst. A hygroma is a fluid-filled sac that develops near joints, often occurring in dogs. Lymphoceles are collections of lymphatic fluid that can occur in the inguinal or axillary regions. Pseudocysts are cysts that develop from fluid accumulation in the abdomen, pancreas, or other organs. Regardless of the term used to describe this condition, seromas can be easily treated with drainage or observation in most cases.