This depends upon the need to change the size of the breast, the shape or both. Sometimes one breast is normal and the opposite breast needs changing. In some patients both breasts are abnormal and therefore both require surgery.
When the problem is just a question of size there are three options.
The choice depends on the size and shape of the breasts and patient choice. All can be excellent options. Doing a breast enlargement leaves very few scars on the breast but does mean that one or both breast have an implant which can give different shape and behaviour over the years. By contrast a breast reduction leaves scars on a breast but does tend to give a better life long solution to the problem (in that breast implants often need repeat surgery at some point in life).
When the problem also includes the shape then it can become more complicated. Treatment usually involves a form of breast up-lift and reshaping but may also use breast implants. When there is very little breast then the skin may need stretching with a
medical balloon device called a tissue expander. This is placed under the breast skin and expanded over months or years before a permanent silicone implant is used.
In summary a lot can be done to improve unequal breast size and shape. The techniques can be a combination of breast reduction, mastopexy (breast lift), breast enlargement and reconstruction with a tissue expander and breast implants. All these techniques are discussed in their respective information sheets.
The options appropriate to each patient will be presented at consultation and a decision made as to which is the most appropriate method for that individual.