3 conditions are necessary for a patient to reach prior to being categorized as brain dead which include being within a persistent comatose state which does not respond to pain stimuli (e.g. nail bed pressure, sternal rub, pressure upon the orbital rim of the face etc.), possessing absent brain stem reflexes (e.g. pupillary light reflex, oculocephalic reflex, coughing gag reflex etc.), and possessing a lack of spontaneous respiration, if a patient is unable to breathe upon their own accord. If a patient possesses all 3 of these metrics, they are considered brain dead and legally deceased within the U.S.. If tests are inconclusive, ancillary examinations can be provided to determine definitively whether or not a person is brain dead (e.g. electroencephalograph, transcranial doppler ultrasound, diagnostic cerebral angiogram etc.) as well as other tests which can be performed