Lumpectomy 3 wks ago. Large hematoma 4 days post op. Any suggestions?

You should be in contact with your surgeon to be see in person for an evaluation. Best of luck, Regards, 

The proper management of a significant hematoma is incision and drainage surgically. This will shorten the healing interval and decrease the risk of infection.

A hematoma of the size you describe open to the environment is a huge breeding ground for bacteria.  You need to call your surgeon ASAP and have the hematoma evacuated in an operating room under sterile conditions.  Hematomas occur in all specialties of surgery and the best surgeons in the world, if they are still practicing, get hematomas (hopefully rarely).  When these occur and are treated immediately, they rarely affect the appearance of the breast, rarely get infected, and heal quite well.  Conversely, if not treated expeditiously, they can lead to a true mess.  I said it already but I will say it again, call your surgeon ASAP.

Thank you for your question. I am sorry to hear of your post-operative complication. This needs an in-person examination today. A hematoma this large needs to be evacuated in the operating room. Please see your surgeon promptly to address this problem. Good luck.

Thank you for your question and I am sorry to hear of your hematoma.  Though nothing replaces an in-person examination or series of photographs, a hematoma of that size should be surgically evacuated, residual bleeding controlled, and the incision closed.