DDx stands for which of the following?

• A. Differential diagnosis
• B. Direct diagnosis
• C. Diagnostic data exchange
• D. Differential data exchange

Answer: (A)

Differential diagnosis is the process of listing multiple plausible causes for a patient’s presentation and then narrowing that list using history, exam findings, and tests to reach the most likely explanation. The shorthand DDx is the standard way clinicians refer to this process in notes and conversations. It emphasizes weighing varied possibilities and prioritizing serious or likely conditions to guide further workup and management. The other options aren’t used in clinical practice to describe this concept—they don’t represent a recognized approach or acronym in medical reasoning. For example, chest pain prompts a differential diagnosis that might include myocardial infarction, pulmonary embolism, aortic dissection, GERD, or musculoskeletal pain, and the clinician works through these possibilities one by one to determine the correct cause.