A medical procedure is defined as non-invasive when no break in the skin is
created and there is no contact with the mucosa, or skin break, or internal body
cavity beyond a natural or artificial body orifice. For example, deep palpation
and percussion are non-invasive but a rectal examination is invasive. Likewise,
examination of the ear-drum or inside the nose or a wound dressing change all
fall outside the definition of non-invasive procedure. There are many
non-invasive procedures, ranging from simple observation, to specialised forms
of surgery, such as radiosurgery.