A review of a plan's decision to deny coverage for or payment of a service by an independent third-party not related to the plan. If the plan denies an appeal, an external review can be requested. In urgent situations, an external review may be requested even if the internal appeals process isn't yet completed. External review is available when the plan denies treatment based on medical necessity, appropriateness, health care setting, level of care, or effectiveness of a covered benefit, when the plan determines that the care is experimental and/or investigational, or for rescissions of coverage. An external review either upholds the plan's decision or overturns all or some of the plan’s decision. The plan must accept this decision.