Final answer:
In an emergency, an enrollee of an HMO with a gatekeeper system should go to the nearest emergency facility without needing prior authorization.
Step-by-step explanation:
When an enrollee of a health maintenance organization (HMO) with a gatekeeper system needs emergency health services, they should immediately seek care at the nearest emergency facility. HMO plans, which often require going through a primary care physician for referrals to specialists, generally provide coverage for emergency medical conditions regardless of the provider's network status. In the case of a true emergency, enrollees are not required to obtain prior authorization and should prioritize promptly addressing their urgent health needs.