Differential diagnosis
Also called Differential, DDx
A differential diagnosis is a ranked list of the conditions that could explain a patient's problem, with the reasoning for each position.
Why it matters in a workup
Rank it by likelihood and keep the dangerous causes you have not excluded in view. A list with no order gives the reader little to act on.
Write a line on why each item ranks where it does. That line is what lets the next doctor continue your reasoning.
Put it into practice
- Put the most likely cause first
- Keep serious causes listed until excluded
- Note what supports and argues against each
Frequently asked questions
How long should a differential be?
Usually three to five ranked items with reasoning. A longer unranked list is harder to act on.
General guidance on clinical documentation, not advice about any individual patient and not legal advice.
Glossary
Look up related terms
- Working diagnosisA working diagnosis is the explanation you act on until new information confirms or replaces it, usually the top of your differential.
- Pre-test probabilityPre-test probability is how likely a condition is before a test, based on age, sex, risk factors and symptoms. It decides how much a result should move you.
- Clinical reasoningClinical reasoning is how a clinician gathers information, weighs it and reaches a diagnosis and plan, including the checks against common errors.