differential-dx

name	differential-dx
description	Build structured differential diagnoses from a clinical presentation — ranked by likelihood, with key discriminators and suggested workup.
version	1.0.0
author	Gnostor Community
license	MIT
metadata	{"hermes":{"tags":["medical","differential","diagnosis","clinical-reasoning","workup","healthcare"]}}

Differential Diagnosis

Generate a structured differential from a clinical presentation, weighted by pre-test probability and discriminating features. Designed as a reasoning aid for clinicians and a teaching tool for trainees.

Disclaimer: This skill is a clinical reasoning aid for licensed professionals and medical learners. It does not replace clinical judgment, examination, or consultation. Never use the output for self-diagnosis or to direct patient care without clinician review.

When to Use

• "Give me a differential for [presentation]"
• "What else should I be considering for this patient?"
• "Rank these diagnoses by likelihood given [findings]"
• "What's the can't-miss diagnosis here?"
• "Build a workup plan for this differential"

What to Give Me

• Demographics: age, sex, relevant social and family history
• Chief complaint and duration
• HPI: onset, character, location, radiation, associated symptoms, modifying factors
• Pertinent positives and negatives on review of systems
• Exam findings and any results already available
• Setting: outpatient, ED, ICU — base rates differ

Output Structure

## Differential Diagnosis: [presentation summary]

### Most Likely (work up first)
1. **[Diagnosis]**
   - Why it fits: [supporting features]
   - Key discriminator: [test or finding that confirms or excludes]
   - Workup: [next-step tests]

2. **[Diagnosis]** — [same structure]

### Must-Not-Miss (rule out even if less likely)
- **[Diagnosis]** — high-morbidity if missed
  - Why considered: [trigger features]
  - Rapid rule-out: [test that excludes urgently]

### Also on the List
- [Diagnosis] — [one-line rationale]
- [Diagnosis] — [one-line rationale]

### Discriminating Workup
| Test | What it tells us |
|------|------------------|
| [Test] | [Helps distinguish A from B] |

### Red Flags Requiring Escalation
[Symptoms or findings that change the disposition]

Reasoning Principles

• Pre-test probability first — base rates anchor the differential
• VINDICATE / surgical sieve as a checklist to avoid premature closure: Vascular, Infectious, Neoplastic, Degenerative, Inflammatory, Congenital, Autoimmune, Traumatic, Endocrine
• Can't-miss diagnoses stay on the list even at low probability if morbidity is high
• Discriminating tests — favor those that meaningfully shift probability over shotgun panels
• Bayesian updating — be explicit about how each new finding moves the prior

Common Presentations

• Chest pain, shortness of breath, syncope
• Abdominal pain, GI bleeding, jaundice
• Headache, altered mental status, focal neuro deficit
• Fever of unknown origin
• Joint pain, rash, swelling
• Pediatric fever, failure to thrive
• Psychiatric: psychosis, mood, suicidal ideation