Often just a surgical bra is uses after a reconstruction. If a free flap or a pedicle flap was used, many times a bra is not worn to avoid compression of the blood supply to the tissue.
You are usually supplied with a bra after your reconstruction procedures so you do not need to worry about getting one. However, if you would like an additional bra, your best bet is a cotton sports bra that is larger than your frame with a zipper in the middle. Best wishes, Dr. T.