San Francisco Syncope Rule Calculator

San Francisco Syncope Rule Calculator for Emergency. Positive markers warrant attention within the complete assessment. A zero result is not a discharge recommendation: the external validation cohort reported serious outcomes that the rule missed. An ECG summary also cannot substitute for interpretation of available tracings and clinically indicated rhythm monitoring.

For shared guidance on choosing a tool and documenting results, read the clinical calculator workflow.

How this calculator works

This is a historical five-marker rule, not an explanation of why a patient fainted. It checks clinician-interpreted ECG abnormality, shortness of breath, heart-failure history, hematocrit below 30% and triage systolic pressure below 90 mmHg. Each positive marker contributes one to the displayed count, but the original classification depends on whether any marker is present.

When to use this calculator

Use only as an adjunct after the initial adult emergency assessment for syncope or near-syncope. Definite seizure and loss of consciousness associated with trauma, alcohol or drugs are outside the supported workflow. A serious cause already identified should be managed directly rather than relabeled through a score.

Inputs used

  • Adult syncope or near-syncope, initial ED evaluation completed and exclusions absent?
  • History of congestive heart failure?
  • New ECG change or non-sinus rhythm identified by a clinician?
  • Shortness of breath associated with the presentation?
  • Hematocrit (%)
  • Triage systolic blood pressure (mmHg)

Clinical interpretation

Positive markers warrant attention within the complete assessment. A zero result is not a discharge recommendation: the external validation cohort reported serious outcomes that the rule missed. An ECG summary also cannot substitute for interpretation of available tracings and clinically indicated rhythm monitoring.

Worked example

With no history, ECG or breathing marker, hematocrit 30% and systolic pressure 90 mmHg give zero listed markers. A hematocrit of 29.9% adds one; pressure 89.9 mmHg adds another. A hematocrit entered as 0.30 L/L converts to 30%, preserving the same boundary.

Limitations and safety notes

The derivation's performance is not a guarantee in a new population. This calculator does not assess orthostatic physiology, medication effects, structural heart disease or all dangerous causes. It supplies no probability and no automated admission decision. Observations are not independently verified.

Frequently asked questions

Is 90 mmHg positive?

Not for this particular rule, whose threshold is strictly below 90. Clinical hypotension still requires assessment.

Does a zero count mean benign syncope?

No. Zero means none of these five markers was entered; it cannot establish a cause or exclude a later event.

Why not display the derivation sensitivity as reassurance?

Study performance is population-dependent and external validation missed events. It is not a patient-specific safety guarantee.

References

  • Quinn2004 derivation: five markers, strict hematocrit and pressure boundaries. https://pubmed.ncbi.nlm.nih.gov/14747812/
  • Quinn2006 prospective study: ECG definition and exclusion context. https://pubmed.ncbi.nlm.nih.gov/16631985/
  • Sun2007 external cohort: missed outcomes and lower performance than derivation. https://pubmed.ncbi.nlm.nih.gov/17210201/

Editorial review and citation methodology

Maintained by the Quick Medical Calculator Editorial Team. Content record date: September 9, 2026. A content date is not evidence of independent clinical review. Individual clinical sign-off is not recorded on this page.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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