Is this a bursa or seroma, or just a blister? (Photo)

Hi there,An ultrasound +/- needle aspiration will quickly give you the answer you need. I would suggest returning to see  your plastic surgeon ask is best for him/her to be driving the investigation.All the best,James

The problem may represent a hematoma (collection of blood under the skin) or a seroma (collection of serum under the skin).  The redness may represent an infection such as an abscess (infection of the fluid) or cellulitis (an infection of the overlying skin).  Whatever the cause or diagnosis, close followup and care are required to treat the problem.