In recent posts we explored the mechanism and systems framework to approach patient presentations. This week, we will introduce the anatomic framework as a common approach to organizing differential diagnoses. This is is particularly powerful for patients with pain complaints.

Case: You’re seeing a male patient with acute right upper quadrant pain. In this case, you map common disease entities from their anatomic structures.

With the anatomic framework, you structure your differential diagnosis around what structures are in that area that could be causing the sign or symptom. These considerations will help you decide what exam maneuvers and tests to perform. As mentioned previously, this is particularly effective for pain complaints (abdominal pain!) and also musculoskeletal complaints.

Back to the case: You learn that your patient has been nauseated for two days with post-prandial vomiting and pain radiating to his back. He does not have pleuritic chest pain, dysuria, frequency, urgency, or hematuria. He has no history of substance use. On exam you note right upper quadrant guarding, rebound tenderness, and positive murphy’s sign. The rest of the exam is unremarkable.

You are confident through your checklist, history, and physical exam that you have ruled out some causes of his right upper quadrant pain. Your remaining differential before any tests are ordered is cholecystitis, biliary colic, pancreatitis, and hepatitis.

Key Take Home Points:

1. The anatomic framework identifies which structures are in the area of concern, and this helps inform the differential diagnosis, exam maneuvers, and investigations that should be ordered.

2. The anatomic approach can be particularly useful for pain complaints.

Stay tuned for part 4, where we will explore the mnemonic/checklist framework.

References/Readings

1. Check out this excellent podcast on diagnostic reasoning, https://imreasoning.com/.

2. Acute abdominal pain resource: https://www.aafp.org/pubs/afp/issues/2008/0401/p971.html