San Francisco Syncope Rule (CHESS)
San Francisco Syncope Rule (CHESS mnemonic) — any one positive criterion marks high risk for a serious 7-day outcome; all negative marks low risk.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Abnormal ECG
- Yes
- Triage systolic BP < 90 mmHg
- Yes
Result: High risk for a serious 7-day outcome — CHESS positive: abnormal ECG, systolic BP < 90 mmHg.
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Any CHESS item
- High risk for a serious 7-day outcome when any of CHF, Hct < 30%, abnormal ECG, shortness of breath, or SBP < 90 is positive.
- All negative
- Low risk when all five are negative; ~96% sensitivity as a rule-out. A risk category, not an admission or discharge order.
What you enter
- History of congestive heart failure
- Hematocrit < 30%
- Abnormal ECG (new change or any non-sinus rhythm)
- Shortness of breath
- Triage systolic BP < 90 mmHg
How this is calculated
Quinn JV, Stiell IG, McDermott DA, Sellers KL, Kohn MA, Wells GA. Derivation of the San Francisco Syncope Rule to predict patients with short-term serious outcomes. Ann Emerg Med. 2004;43(2):224-232. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.