Final answer:
A Health Maintenance Organization (HMO) requires a primary care physician for all referrals, as they serve as gatekeepers for accessing specialist services and ensuring cost-effective care.
Step-by-step explanation:
The health care organization that typically requires a primary care physician for all referrals is a Health Maintenance Organization (HMO). In HMOs, patients select a primary care physician who becomes the gatekeeper for all their health care services, including referrals to specialists. Members are generally required to get a referral from their primary care physician before they can see a specialist or receive certain medical services, ensuring that care is coordinated and costs are managed effectively.
HMOs are designed to bring down the cost of health care and increase the quality of the care given by promoting preventative care and limiting unnecessary procedures. These organizations have become integral in efforts to control rising health care costs and improve efficiency within the healthcare system in the United States.