Swelling is any abnormal enlargement of a body part. This can be due to fluid - including blood - bony malformation, muscle, or any number of things. Edema describes fluid, or swelling, that has accumulated in the tissue. Acute swelling refers to swelling that occurs within 24 hours of injury. If the swelling occurs within the first 2 hours, it is probably associated with hemarthrosis (blood in edema), and should be checked out by a physician. Chronic swelling refers to swelling that occurs over a long period of time, and can be difficult for an athlete to detect, but is dangerous if left untreated.