Differential Diagnosis & Clinical Reasoning Worksheet
Building a differential diagnosis requires more than listing conditions that could explain a patient’s symptoms. Clinical reasoning involves developing a working set of possibilities, deciding which diagnoses deserve the most attention, and revising that reasoning as new information becomes available.
The Differential Diagnosis & Clinical Reasoning Worksheet is designed to make that reasoning visible. It can be used during clinical rotations, case preparation, post-encounter review, or coursework that requires students to explain how they moved from a patient presentation to a prioritized differential.
What This Worksheet Helps You Do
The worksheet follows the iterative diagnostic process described by the National Academies of Sciences, Engineering, and Medicine, moving from an initial problem representation through a prioritized differential and then back to re-ranking as additional information becomes available (National Academies of Sciences, Engineering, and Medicine [NASEM], 2015).
It helps organize:
- a concise problem representation;
- a prioritized differential;
- findings that support or weaken each diagnosis;
- dangerous alternatives and cannot-miss features;
- information that could change testing, treatment, disposition, or follow-up;
- the purpose of diagnostic testing; and
- re-ranking after new information becomes available.
The worksheet is a framework for organizing clinical reasoning, not a diagnostic algorithm or substitute for clinical judgment.
Start With the Problem Representation
The worksheet begins with a one-line problem representation and a prompt to identify what makes the case distinctive.
A useful problem representation compresses the features that meaningfully distinguish the presentation and change the differential. A problem representation should capture the clinical features that distinguish the presentation without reproducing the entire history.
Build a Prioritized Differential
The differential table asks you to document why each diagnosis remains under consideration instead of creating an unranked list.
For each diagnosis, identify findings that support it and findings that are absent, inconsistent, or still unknown. The worksheet also separates likelihood from cannot-miss features so that consequence remains visible when diagnoses are prioritized.
AHRQ describes diagnostic reasoning as synthesizing available information into a prioritized differential diagnosis (Agency for Healthcare Research and Quality [AHRQ], 2022). NASEM further describes the working diagnosis as a process of generating and refining diagnostic possibilities as information accumulates. A differential may begin relatively broad and become increasingly focused as the clinical picture develops (NASEM, 2015).
Identify What Could Change Your Mind
The worksheet asks you to identify information that could move a diagnosis higher or lower on the differential or change the management plan. This creates a deliberate point for reassessment when later findings no longer fit the initial impression.
Connect Testing to a Clinical Decision
The testing and management section asks three practical questions:
What am I trying to learn from this test?
Identify the diagnostic uncertainty the test is intended to reduce.
Would the result change management?
Consider what would change depending on the result.
What can be decided clinically?
Identify which parts of the assessment can reasonably be addressed through the history, examination, clinical course, or other information already available.
These questions help connect diagnostic testing to the decision it is meant to inform.
Re-Rank the Differential
The final section asks you to rank the differential again after additional information becomes available. Diagnoses may move higher, move lower, or leave the active differential as the clinical picture changes.
Re-ranking makes the change in reasoning visible and reinforces that the differential is a working clinical tool.
Download the Worksheet
Blank Differential Diagnosis & Clinical Reasoning Worksheet
Use the blank version for clinical cases, simulation, coursework, or independent practice.
Completed Fictional Example
See how the sections work together in a fictional outpatient case. The example demonstrates a reasoning process and is not a diagnostic algorithm.
Course, faculty, preceptor, and clinical-site requirements should take precedence when they differ from the structure used in this resource.
Continue With Clinical Reasoning
The companion guide, How to Build a Differential Diagnosis Without Anchoring Too Early, examines anchoring, premature closure, discordant findings, diagnostic momentum, and when new information should reopen the differential.
Use the guide alongside the worksheet when you want to examine the reasoning behind how diagnoses are added, prioritized, or reconsidered.
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References
Agency for Healthcare Research and Quality. (2022). Foundations of diagnosis education. https://www.ahrq.gov/diagnostic-safety/resources/issue-briefs/education-dx-outcomes-2.html
National Academies of Sciences, Engineering, and Medicine. (2015). Improving diagnosis in health care. The National Academies Press. https://doi.org/10.17226/21794