Why Sizing Is Complex
Implant size selection is not simply choosing a volume from a menu. The same implant volume produces dramatically different results in different patients depending on: chest wall width, existing breast tissue volume, skin elasticity and compliance, breast base width, nipple-to-fold distance, and tissue thickness. 400cc in a patient with a wide chest and substantial existing tissue looks very different than 400cc in a patient with a narrow chest and minimal starting volume.
Base Width Measurement
The breast base width (the horizontal width of the breast footprint on the chest wall) is the primary anatomical constraint in implant selection. Surgeons measure base width in centimetres and select implants whose diameter approximates or slightly exceeds this measurement. Implants substantially wider than the base width will have visible or palpable lateral edges; implants substantially narrower may not provide adequate lateral fill. This is why identical heights can wear very different implant sizes.
Sizers and Dimensional Planning
Physical breast sizers (temporary implant shells of known volume) can be placed inside a specially sized bra to give patients a visual preview of approximate results. Allergan's VECTRA 3D imaging system projects surgical outcomes onto a 3D model of the patient's body, allowing visualisation before surgery. Both methods have limitations — actual surgical results depend on how the specific implant interacts with the specific tissue — but they improve communication between patient and surgeon.
The Rice Test
A simple home method for approximating implant size involves putting measured quantities of uncooked rice in a zip-lock bag and placing it inside a bra to simulate different volumes. While imprecise, it allows patients to experience the weight and approximate visual effect of different volumes before consulting with a surgeon, and helps articulate goals more specifically.
