The one diagnosis from a differential list used to base the patient's treatment plan is referred to as the:

The designation of the diagnosis used to guide a patient's treatment plan is referred to as the Working Diagnosis. This term reflects the ongoing assessment and adjustments that a clinician may need to make as new information arises during the treatment process. It implies that while the diagnosis is currently deemed the most likely explanation for the patient's symptoms, it may be adjusted as more data becomes available or as the patient's condition evolves.

A Working Diagnosis is foundational in clinical practice since it allows healthcare providers to formulate and implement a treatment plan based on the diagnosis they believe is most appropriate at that time. This diagnosis may be revisited and changed in light of new evidence, making it a dynamic component of patient management.

Other diagnoses listed, such as Final, Probable, and Provisional Diagnoses, have distinct meanings but do not capture the same level of ongoing assessment and potential for adjustment that a Working Diagnosis encompasses. A Final Diagnosis usually indicates a more definitive determination that likely matches the patient's existing condition with less immediate need for revision. In contrast, a Provisional Diagnosis suggests a temporary categorization awaiting further confirmation, while a Probable Diagnosis indicates a strong likelihood, yet it does not emphasize the ongoing evaluation aspect inherent in a Working Diagnosis.