[quote]You can't just make an appointment with an ENT you have to be referred.[/quote]The USA has two primary models: PPO and HMO. One allows subscribers to go to any provider they choose with out referral while the other requires your primary to make all specialist referrals. There is a network concept with both and in-network providers provider more coverage for less while out-of-network providers can offer whatever service you need but the cost to the subscriber is higher, often a lot higher.

Good luck