Physicians who perform independent medical reviews must be Board Certified and in active practice in that same area of treatment. These physicians are contracted by an Independent review organization, medical management companies, third party administators (TPAs), or utilization review / utilization management companies to provide objective, unbiased determinations on what the root cause of the treatment was, whether or not there is medical necessity, if there was a sentinel event, what was the reason for it, etc.
Terms that medical professionals use that are synonomous with "Independent Medical Review" include "External Medical Review", "Medical Peer Review", "Peer Review", or Hospital Peer Review(if the sentinel event happened at a hospital).