Blog | Tuesday, April 20, 2021

Some thoughts on diagnostic reasoning

Yesterday I tweeted about our success in making some worthwhile diagnoses in the category of unusual presentations of common diseases. As I consider these successes, the principles of diagnostic aggressiveness become central to my thoughts.

For arguments sake let's imagine three types of diagnostic reasoning. The first occurs when there is no diagnosis but we know something is wrong. These patients generally require a broad differential and much clinical thought. We often go back and collect more history, repeat the physical exam and think broadly about labs and imaging. We often need several consultants and often biopsies.

The second version includes the majority of patients – a straightforward diagnosis. We need not spend much time on diagnosis unless the respond to treatment raises warnings that we might have the wrong diagnosis.

The third version involves patients whose presentation involves some subtleties. These are the patients who too often do not stimulate diagnostic curiosity. Yet, when we pay attention to the subtle clues, we often reopen the diagnostic process. The most fulfilling diagnoses that I and my teams have made occur in this latter category.

This fits an Osler quote, “The value of experience is not in seeing much, but in seeing wisely.” The astute diagnostician observes a lab, or physical finding, or imaging finding that does not fit the assumed diagnosis, and has courage to question that diagnosis. Sometimes the trigger finding does not yield a new diagnosis, but we still have the responsibility to wonder, think, and pursue another diagnostic possibility.

We have presented two such cases in our @unremarkablelab YouTube videos: and –

db is the nickname for Robert M. Centor, MD, MACP. db stands both for Dr. Bob and da boss. He is an academic general internist at the University of Alabama School of Medicine, and the former Regional Dean for the Huntsville Regional Medical Campus of UASOM. He still makes inpatient rounds regularly at the Birmingham VA and Huntsville Hospital. His current titles are Professor-Emeritus and Chair-Emeritus of the ACP Board of Regents. This post originally appeared at his blog, db's Medical Rants.