What Bra Size is a 397cc Implant?

I would guess that this would be a full C or D cup.  In order to make an accurate size recommendation, I would need to assess your chest wall and breast mound measurements and characteristics.  Unfortunately, there is not a general rule of thumb or objective criteria to implant selection.
Your plastic surgeon will perform several measurements of your chest wall and breast anatomy and determine a range of implants that both fit your chest wall and reach your desired goals.
The next step is to try on this range of implants in the office with your doctor.   The key to this success is showing your surgeon the body proportion you desire with a bra sizer and allowing your surgeon to guide you to the right implant.   It will be much easier to communicate in implant cc's than cup size when determining the appropriate implant for you.
I wish you a safe recovery and fantastic result.
Dr. Gill

It is difficult to determine cup size pre-operatively. Every manufacturer produces a variety of bra styles, which may differ in size and shape. Clear communication with your plastic surgeon is important in achieving the desired goals of the patient.  I like to communicate with patients with “goal” pictures.  During surgery, I use temporary sizers to determine the size/profile that will give the patient the look she is looking for. Trying to predict the size of the implant preoperatively is not ideal.  I think it is too much responsibility for the patient to choose the size of the implant.  Ideally, the surgeon would make that determination once he/she is in the operating room with sizers in and examining the patient in the upright and supine position.  There are many variables that come into play when choosing the correct implant size (how much breast tissue the patient currently has, the shape of the chest wall (concave vs. convex), etc..  Some places have you put bags of rice or implants in your bra – that is normally not very accurate.