A System for Differential Diagnosis

Given the objective of this site – namely to approach the evaluation of patients in a systematic fashion – I thought it would be useful to put some thought into how best to develop these systems. The method I’ll detail below might be cumbersome to apply in every situation, but (at this point at least) it is the best way to ensure that nothing is overlooked.

A System for Differential Diagnosis:

A system for systems

Any illness or abnormality for which a patient could seek medical attention (or a colleague, consultation) can be broadly encompassed by the statement above. The differential diagnosis is developed by delineating the chief concern(s) or primary aberrant signs, and selecting a relevant mixture of disease processes and organ systems. The differential can be narrowed by determining subjective and objective details surrounding the chief concern. The differential can be broadened by expanding each major category into subcategories.


  1. Benbassat, J., & Bachar-Bassan, E. (1984). A comparison of initial diagnostic hypotheses of medical students and internists. Journal of medical education, 59(12), 951–956.
  2. Bowen, J. L. (2006). Educational strategies to promote clinical diagnostic reasoning. The New England journal of medicine, 355(21), 2217–2225. doi:10.1056/NEJMra054782
  3. Coderre, S., Mandin, H., Harasym, P. H., & Fick, G. H. (2003). Diagnostic reasoning strategies and diagnostic success. Medical education, 37(8), 695–703.
  4. Fulop, M. (1985). Teaching differential diagnosis to beginning clinical students. The American journal of medicine, 79(6), 745–749.
  5. Graber, M. L., Tompkins, D., & Holland, J. J. (2009). Resources medical students use to derive a differential diagnosis. Medical teacher, 31(6), 522–527.
  6. Sapira, J. D. (1981). Diagnostic strategies. Southern medical journal, 74(5), 582–584.

Intro to “DDx of”

I’m a medical student currently rotating through clinical clerkships resident in emergency medicine. The purpose of this website is to force me to learn. Recently, I’ve found it increasingly difficult to study from review books, and even more difficult to recall and apply that information practically. What has been working is reading heavily about specific cases I’ve seen. Having a real person in mind, hearing their complaints, doing their examination and then supplementing the experience with targeted reading sticks far better.

As for the format, something that has been hammered into me over the past year is to be systematic in everything I do. The benefits being that I’m less likely to miss stuff if I approach everything the same way. The other benefit for me is that I find these systems to be a better way to learn. Less mnemonics, more flowcharts.

So, I’ll select appropriate cases I encounter (altering identifying information of course), read into it a bit, and create a systematic approach for the evaluation, diagnosis and management of that chief complaint.

The site’s going to be a bit rough, the goal is to make it easy to quickly archive these experiences for future reference and learning.