Incision wound blistering after bunionnectomy

Dear Ask The Doctor: I had a bunionectomy 6 weeks ago. The incision wound had been healing well until today. I noticed what looks like a blood blister forming right on top on the scar where the incision was made. It is extremely tender and very purplish. should I be concerned or is this just part of the healing process? Thank you:)

Dear Amy: This development is not normal. You will need your surgeon to assess your wound as soon as possible. It is possible that you have developed an infection or a hematoma. A hematoma is a collection of clotted blood. It may resolve on its own without treatment but may also become infected and thus may require minor surgery. You doctor will determine the appropriate treatment after he/she has assessed the wound.