Clinical Reasoning Exercises
Diagnostic Schema
Download Introduction
A diagnostic schema is a cognitive tool that allows clinicians to systematically approach a clinical problem by providing an organizing scaffold. A commonly used schema for acute kidney injury (AKI) separates this problem into pre-renal, intrinsic, and post-renal causes. By approaching AKI using these categories, clinicians can systematically access and explore individual illness scripts as potential diagnoses.
Because they can be retrieved and manipulated as a single item within the working memory, schema also help clinicians to manage their cognitive load and maintain the bandwidth for effective problem-solving.
Examples of basic diagnostic schema include:
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Clinical Problem/Syndrome
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Basic Diagnostic Schema
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Bilateral lower extremity edema
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Cardiac, Liver, Renal, Vascular, Lymphatic
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Anemia
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Blood Loss; Decreased Production; Increased Destruction
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Intrinsic Renal Injury (sub-category of AKI further elaborated)
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Glomerular; Tubular; Interstitial; Vascular
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Sound diagnostic schema help clinicians:
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Tether diagnostic thinking to a logical framework (i.e., structural/anatomic, physiologic, etc.) that can be more easily remembered
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Avoid missing categories of illness, or anchoring on the most familiar diagnoses
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Expand their differential diagnosis for a complex problem
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Trigger differentiating historical or physical exam maneuvers to refine the differential diagnosis (i.e., when activated during a clinical encounter, the schema for volume overload may prompt the clinician to check the Jugular Venous Pressure as that will help to differentiate among the potential diagnostic categories for this problem)
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Teach others how to approach a given clinical problem (‘think aloud’)
Through deliberate practice, learners adapt and individualize their schema—tying these frameworks to prior clinical knowledge and experience, which keeps them robust and accessible. Over time individuals may find that collapsing certain categories, or creating new ones, allows a schema to ‘work’ best for them.
Two cases from the ECR series: When the Script Doesn’t Fit: An Exercise in Clinical Reasoning and Diagnostic Scheming highlight the concept of diagnostic schema. The teaching slides for these cases can be used to bring this key concept to life while reinforcing learners’ medical knowledge.
Case
Teacher's Guide (Case 1)