Yes it is absolutely fine to go flat after mastectomy and forego reconstruction. Not every woman wants to have breast reconstruction and not every woman is a candidate for breast reconstruction. If you choose to go flat, your surgeon will design a different incision on your breast and try to leave you with as smooth of a chest contour as possible without a lot of rolls or excessive skin. The chest will feel totally numb permanently. You can opt for an external prosthesis after your chest has healed from surgery, but there are some inconveniences associated with a moderate to large external breast prosthesis. If you ever decide that you wish to pursue breast reconstruction down the road, there are definitely options.