Which element is NOT considered a key component in determining the level of E/M service?

The determination of the level of Evaluation and Management (E/M) service is based on three key components: History, Examination, and Medical Decision Making. Each of these components contributes to understanding how complex the patient's case is and how much effort is required from the healthcare provider.

History involves the gathering of information about the patient's past medical conditions, current symptoms, and relevant family and social history. This provides the context needed to evaluate the patient effectively. The Examination refers to the physical assessment of the patient, which helps in understanding the patient's current health status. Medical Decision Making involves the complexity of establishing a diagnosis, the number of possible diagnoses, and the risk of complications or adverse outcomes.

In contrast, the Referral Source does not impact the coding of the service level. While it might give context about why the patient is being seen, it does not contribute to the key components that define the complexity or the level of care provided. The coding guidelines specifically emphasize the necessity of history, exam, and medical decision-making in establishing the appropriate E/M service level, making referral source irrelevant in this context.