A small, hand-held, manually-operated, sterile device designed to assist with the location of the subcutaneous injection port of an implanted tissue expander prior to the insertion of a filling needle into the port in order to fill the tissue expander with, e.g., saline. It is moved over the surface of the skin at the point where the concealed injection site is situated and an indicator, e.g., a small magnet, reacts to the metal material of the port, indicating where it is located. Repetition of this locating process on several axes provides the exact location of the injection site. This is a single-use device.