Thank you for your question regarding how you can tell if you have a seroma or just swelling. Basically, the safest thing to do is to visit with your plastic surgeon. Physical examination is usually the best test. Often, plastic surgeons look for what is called “fluid wave”. To do a fluid wave test, you tap on one specific area of the mass in question. If you see fluid propagate or move to another area (like a wave in the pool), then that typically, means there is fluid underneath the mass. This would mean that you have a fluid collection or seroma. If you have a seroma, serial needle aspiration or an insertion of the drain is required. Please consult with your experienced, board-certified plastic surgeon. I hope that I have answered your question regarding the presence of a seroma or just swelling. If you have any more questions, please contact my office. Sincerely, Dr. Katzen