If it were me, i would get a tattoo above the location saying that there is removable material underneath, and get it added to you medical records. There probably should be a way to tattoo a universal message for the medical profession [1], i.e. 'do not resuscitate', 'allergic to X', 'metal under skin here', etc. There are relatively universal signs for magnets for example [2].

[1] https://www.health4you.co.za/directory/category/tattoos/medi...

[2] https://openclipart.org/detail/281487/magnets-warning-symbol