⚡ Promptolis Original · Healthcare & Medical
🧠 Differential Diagnosis Scaffolder
For clinicians: a structured differential with priors, can't-miss diagnoses, and the one test that actually changes your management.
Why this is epic
Separates prior probability (what's common) from posterior stakes (what will kill your patient if missed) — most AI differentials blend these and produce noise.
Names the single highest-yield test per diagnosis, not a shotgun workup. Forces Bayesian reasoning, not pattern-matching.
Explicitly scaffolds YOUR reasoning — it does not diagnose. You remain the clinician; the tool prevents premature closure and anchoring bias.
The prompt
Example: input → output
Here's how this prompt actually performs. Real input below, real output from Claude Opus 4.
Chief complaint: Pleuritic left-sided chest pain, 6 hours Patient demographics & relevant PMH: 34F, BMI 31, on combined OCP x 4 years, no tobacco, returned 2 days ago from a 9-hour flight from Istanbul. No prior DVT/PE. No cancer history. G1P1, LMP 3 weeks ago. HPI: Sudden-onset sharp left chest pain, worse with deep inspiration, mild dyspnea on exertion climbing her apartment stairs. No fever, no cough, no hemoptysis, no leg swelling or pain. No recent URI. No trauma. Denies palpitations. Pain is 6/10, non-radiating. Exam: HR 104, BP 128/78, RR 20, SpO2 96% on RA, T 37.1°C. Alert, mildly anxious. Lungs: clear bilaterally, no pleural rub. Heart: tachycardic, regular, no murmur. Calves: soft, non-tender, symmetric, no Homans. No chest wall tenderness on palpation. Available data: ECG shows sinus tachycardia at 104, no S1Q3T3, no new T-wave inversions. CXR pending. Troponin pending. D-dimer not yet drawn. Setting & resource constraints: Community ED, CT-PA available, ultrasound available, no on-site cardiology. Clinician's current leading diagnosis: PE
Differential Scaffold: 34F with pleuritic chest pain, tachycardia, and recent long-haul flight on OCP
Pretest Context
This patient has three stacking thrombotic risk factors: combined OCP (roughly 3-4x baseline VTE risk), BMI 31, and a 9-hour flight within 72 hours. Her Wells score is approximately 4.5 (tachycardia +1.5, PE as most likely dx +3) placing her in the moderate-probability group where D-dimer is not appropriate as a rule-out — she needs imaging. Your leading diagnosis of PE is well-calibrated; the job of this scaffold is to make sure you don't miss the alternatives and to prevent premature closure once CT-PA results arrive.
Top 5 by Prior Probability (in THIS patient)
| Diagnosis | Prior | Supporting | Disconfirming | Highest-Yield Test | What Changes Management |
|---|---|---|---|---|---|
| Pulmonary embolism | ~35-45% | OCP + flight + BMI, unexplained tachycardia, pleuritic pain, mild exertional dyspnea | No leg findings, SpO2 96%, no hemoptysis | CT-PA | Positive → anticoagulate; negative at this pretest probability effectively rules out |
| Musculoskeletal / costochondritis | ~15-20% | Young, pleuritic quality can mimic | No chest wall tenderness on palpation (significant against) | Reproduction of pain on palpation | Diagnosis of exclusion only — do not anchor here |
| Viral pleurisy / pleurodynia | ~10% | Pleuritic character, low-grade temp | No prodrome, no URI symptoms, no rub | CXR + clinical course | Supports only after PE excluded |
| Pneumonia (atypical/early) | ~5-8% | Pleuritic pain, tachycardia | Afebrile, no cough, lungs clear | CXR | Infiltrate reframes workup |
| Spontaneous pneumothorax | ~3-5% | Sudden onset, pleuritic, thin-ish female | Bilateral breath sounds equal, SpO2 96% | Upright CXR (or lung US) | Any pneumothorax → procedural decision |
Can't-Miss Diagnoses (stakes-ranked)
1. Pulmonary embolism — already your leading dx; the risk is *premature de-escalation* if the initial CXR is normal and troponin negative. Do not let a reassuring troponin talk you out of imaging.
2. Aortic dissection — prior <1% but catastrophic. Pleuritic character and lack of tearing/radiating pain argue against; no BP differential noted. Document a bilateral BP and pulse exam. Escalate if any neuro deficit, syncope, or new murmur.
3. Myopericarditis — rare at 34 but OCP does not protect. No pericardial rub, ECG without diffuse ST elevation or PR depression argues against. Troponin will help; if elevated with a negative CT-PA, pivot hard.
4. Tension pneumothorax — she's stable now, but if she deteriorates during CT-PA prep, reassess breath sounds and tracheal position before assuming PE-related decompensation.
The Reasoning Chain
1. Three VTE risk factors + unexplained sinus tachycardia + pleuritic pain = moderate-to-high pretest probability for PE. Wells ~4.5.
2. At this pretest probability, D-dimer is *not* an appropriate rule-out — a negative D-dimer here still leaves meaningful residual risk (~3-5%). Go directly to CT-PA.
3. While awaiting CT-PA: complete CXR (rules in pneumothorax, pneumonia, widened mediastinum), troponin (PE strain vs. myopericarditis), and bedside lower-extremity compression US if available.
4. If CT-PA positive: risk-stratify (sPESI, RV strain on CT, troponin). Most 34-year-olds with submassive-or-less PE go to anticoagulation and admission, not thrombolytics.
5. If CT-PA negative: PE is effectively excluded at this pretest probability. Now re-examine the chest wall carefully, consider pericarditis workup if troponin is positive, and reassess the HR — persistent unexplained tachycardia in a young woman post-flight still deserves a second look.
6. Disposition depends on imaging, but do not discharge with *unexplained* tachycardia, even if imaging is clean.
Cognitive Traps in This Case
- Anchoring on PE — once you've said PE out loud, a normal CT-PA can feel like 'nothing found' and lead to premature discharge. Tachycardia without a diagnosis is a finding, not a wastebasket.
- Young-and-healthy bias — 34-year-old women with chest pain are statistically the most under-worked-up cohort in EDs. Resist the reflex to soften the workup.
- D-dimer temptation — in moderate pretest probability, a negative D-dimer does NOT rule out. Skip it, go to CT-PA.
- OCP-as-explanation-for-everything — the OCP raises VTE risk, but don't let it pre-commit you before imaging.
What I'd Want to Know Next
1. CXR result — rules in/out pneumothorax, pneumonia, widened mediastinum in one test.
2. Troponin — dissociates PE-strain from myopericarditis if CT-PA is negative.
3. Any syncope, presyncope, or exertional symptoms at home she hasn't mentioned — changes PE severity stratification.
Clinician's Call
These are probability estimates on the data you've provided — I haven't seen the patient, and your bedside gestalt outranks any framework. The disposition is yours.
Common use cases
- ED attending working up atypical chest pain at 3am who wants a sanity check before disposition
- PGY-2 on inpatient medicine preparing for attending rounds on a diagnostic dilemma
- Rural family physician without immediate specialist access thinking through next steps
- Hospitalist building a written differential for the chart to document reasoning
- Board exam prep — practicing structured clinical reasoning on vignettes
- Teaching tool for medical students learning illness scripts
- Second-opinion scaffold before consulting specialty or ordering expensive imaging
Best AI model for this
Claude Opus 4 or GPT-5 Thinking. Reasoning depth matters here — faster models tend to produce textbook differentials without calibrating to the specific presentation. Avoid models that refuse medical content categorically.
Pro tips
- Paste actual exam findings, not summaries. 'Lungs clear' is less useful than 'no crackles, no wheezes, symmetric air entry, RR 18'.
- Include pretest modifiers: age, sex, comorbidities, medications, and local epidemiology (e.g., 'endemic Lyme region'). Priors collapse without them.
- If the model produces generic textbook answers, add: 'Rank by prior probability in THIS patient, not in the general population.'
- Always ask for the 'one test' logic — if it can't justify why that test changes management, the differential isn't calibrated.
- Use it BEFORE you look things up, not after. It's a bias check, not an authority.
- Document in your note that AI was used for reasoning scaffolding only, per your institution's policy.
Customization tips
- Swap the <role> block to match your specialty context (e.g., 'senior ED attending' vs 'hospitalist' vs 'pediatric attending') — priors shift meaningfully.
- If you work in a specific epidemiologic context (high TB prevalence, endemic Chagas, high Lyme), add one line to the pretest context instruction to force the model to weight it.
- For teaching, add to the output format: 'After the differential, generate 3 Socratic questions I should ask the learner.'
- Add an 'uncertainty budget' line to force the model to say where it's least confident — useful for high-stakes cases.
- For documentation workflows, add: 'Also produce a 3-sentence reasoning paragraph suitable for the medical decision-making section of the chart.'
Variants
Pediatric Mode
Shifts priors to age-appropriate diagnoses, flags NAT/child-protection red flags, uses weight-based dosing logic.
Resource-Limited Mode
Assumes no CT, no MRI, limited labs — forces differentials answerable with H&P, basic labs, and ultrasound.
Board Exam Mode
Reformats as USMLE/MRCP-style reasoning with classic buzzword associations and most-likely-tested answer.
Frequently asked questions
How do I use the Differential Diagnosis Scaffolder prompt?
Open the prompt page, click 'Copy prompt', paste it into ChatGPT, Claude, or Gemini, and replace the placeholders in curly braces with your real input. The prompt is also launchable directly in each model with one click.
Which AI model works best with Differential Diagnosis Scaffolder?
Claude Opus 4 or GPT-5 Thinking. Reasoning depth matters here — faster models tend to produce textbook differentials without calibrating to the specific presentation. Avoid models that refuse medical content categorically.
Can I customize the Differential Diagnosis Scaffolder prompt for my use case?
Yes — every Promptolis Original is designed to be customized. Key levers: Paste actual exam findings, not summaries. 'Lungs clear' is less useful than 'no crackles, no wheezes, symmetric air entry, RR 18'.; Include pretest modifiers: age, sex, comorbidities, medications, and local epidemiology (e.g., 'endemic Lyme region'). Priors collapse without them.
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