Which requirement must be met when services provided by teaching physicians are billed to Medicare?

When billing Medicare for services provided by teaching physicians, it is essential that the teaching physician is involved in key portions of the service. This requirement ensures that there is an appropriate level of supervision and involvement, allowing the teaching physician to maintain oversight over patient care.

Involvement in key portions implies that the teaching physician has participated directly in the patient's evaluation, treatment, or management. This is critical for Medicare compliance, as it establishes the teaching physician's role in the care delivered to patients while also facilitating the educational aspect where residents can learn under supervision.

The other choices reflect misunderstandings of Medicare billing policies for teaching physicians. For instance, it is not necessary for the resident to manage the patient independently, nor should documentation solely contain the resident's services without acknowledging the teaching physician's role. Additionally, having the teaching physician operate without oversight contradicts the principles of supervised learning in a teaching environment. Proper involvement and oversight are foundational in providing quality care and education.