The possible causes of swollen waist include trauma, infection, lumbar spine tuberculosis, tumor and so on. 1. Trauma: When the lumbar region suffers from impact and other traumatic injuries, it may cause fractures, local soft tissue injuries and other conditions, resulting in swelling, pain and limited movement of the lumbar region. 2. Infection: If the skin or soft tissues of the lower back are infected, it will also show up as swelling, pain, redness, and high local skin temperature in the lower back. 3. Tuberculosis of lumbar vertebrae: Tuberculosis of lumbar vertebrae can cause abscess of the surrounding muscles, which manifests as swelling and severe pain in the lumbar region. 4. Tumor: If tumor occurs in the muscles or soft tissues of the waist, it will also manifest as swelling and pain in the waist. Swelling of the waist may also be caused by other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment.