Items such as gel-filled breast forms and other prosthetics do not need to meet carry-on liquid limit if they are considered medically necessary.
If travelling with a prosthetic, make sure it has no metal parts. Some items underneath clothing may show as an anomaly on the scan and trigger the machine. If this happens, you should explain calmly to the officer what the item is. You should not be asked to remove or raise any items of clothing to reveal the item to them, nor should you be asked to remove it in a public place, but you may be subject to a further search.