What is an external review? External review provides an independent review process for individuals covered by a fully insured Massachusetts health plan who have been denied benefits for reasons of medical necessity. In order to be eligible for external review, the service or supply being requested must be a covered benefit in the particular health plan contract -- that is, it cannot be explicitly excluded from the health plan. Medical professionals who are not affiliated with your health plan review your case and issue a determination. The results of external reviews are binding on your health plan.