For pediatric patients patients see syncope (peds)


  • Transient loss of postural tone and consciousness due to cerebral hypoperfusion
  • Syncope and pre-syncope assessed similarly
  • Important considerations:
    • Is this true syncope or something else (eg, stroke, seizure, head injury)?
    • If this is true syncope, is there a clear life-threatening cause?
    • If this is true syncope and the cause is not clear, is the patient at high risk for serious outcome?

Risk Factors for Serious Cause

  • Exertion preceding the event
    • Note that syncope during exertion much more concerning than syncope after exertion
  • History of cardiac disease in the patient
  • Family history of sudden death, deafness, or cardiac disease
    • Consider unexplained deaths and deaths due to single vehicle accidents
  • Recurrent episodes
  • Recumbent episode
  • Prolonged loss of consciousness
  • Associated chest pain or palpitations
  • Use of medications that can alter cardiac conduction

San Francisco Syncope Rule

  • 1.4% of patients who are rule-negative will have a 7-day serious outcome
  • 10% of patients meeting the below criteria will have a 7-day serious outcome
  • NOT validated by external studies[1]
Criteria (CHESS Pneumonic)[2]

Clinical Features

Physical Exam

Clinical Features by Cause

  • Cardiovascular-mediated syncope
    • Usually occurs without warning (absence of prodrome)
    • History of structural heart disease
    • Family history of sudden cardiac death
    • Syncope during exertion
    • Chest pain or palpitations associated with syncope
    • Abnormal ECG
  • Neurally mediated syncope
    • Trigger event (fear/pain, prolonged standing, warm environment)
    • Prodrome of nausea/vomiting, tunnel vision, lightheadedness, diaphoresis, warmth [3]
    • Associated with head movement or pressure on neck
  • Orthostatic hypotension-mediated syncope
    • After standing up
    • Change in medications

Differential Diagnosis

Syncope Causes


  • Overall yield of testing is low
  • Cardiovascular findings and evidence of bleeding strongest predictors of adverse outcomes after syncope[4]


ACEP only recommends ECG and H&P as must haves

Consider based on history/symptoms
  • CXR
    • Obtain if symptomatic (i.e. to rule out dissection)
  • Hemoglobin
  • Chemistry
    • Capillary glucose assessment sufficient in many cases
  • Orthostatics (symptomatic)
  • Troponin
    • Not recommended to rule out AMI in patients with isolated syncope[8]
    • Elevated troponin predicts adverse cardiac outcome in syncope[9]
    • May be useful for risk stratification
  • Guaiac
  • Bedside US
    • PSL view may show thickened ventricular septum
    • High sensitivity to rule out AAA
  • b-HCG in female patients of reproductive age to rule out ectopic pregnancy rupture as cause of syncope
  • CT scan of head is not recommended in asymptomatic, insignificant trauma with normal neurologic examination
  • Does PE need to be worked up?
    • NEJM paper by Prandoni[10] showed 3.8% of admitted ED pts with syncope had PE
    • 2018 systematic reviewed [11] showed 0.8% of admitted ED pts with syncope had PE



  • Treat underlying cause, if known (~50% of patients do not have a firm diagnosis)



  • Abnormal ECG
  • CHF
  • Suspicion of structural heart disease
    • Ischemic, dysrhythmic, obstructive, valvular
  • HCT <30
  • Shortness of Breath
  • Hypotension(SBP <90)
  • Family history of sudden cardiac death
  • Advanced age
  • Evidence of hemorrhage (occult blood)
  • Syncope without prodrome


  • None of the above findings (esp if age <45)
  • Consider referral for holter or til-table test

External Links

See Also


  1. Birnbaum A, Esses D, Bijur P, Wollowitz A, Gallagher EJ. Failure to validate the San Francisco Syncope Rule in an independent emergency department population. Ann Emerg Med. 2008;52(2):151-9.
  2. Quinn J, McDermott D, Stiell I, Kohn M, Wells G. Prospective validation of the San Francisco Syncope Rule to predict patients with serious outcomes. Ann Emerg Med. 2006 May;47(5):448-54. PubMed PMID: 16631985.
  3. Romme JJCM, van Dijk N, Boer KR, et al. Influence of age and gender on the occurrence and presentation of reflex syncope. Clin Auton Res. 2008;18(3):127-133
  4. D’Ascenzo F, Biondi-Zoccai G, Reed M, et al. Incidence, etiology and predictors of adverse outcomes in 43,315 patients presenting to the emergency department with syncope: an international meta-analysis. Int J Cardiol. 2013;167(1)57-62
  5. Sud S, Klein GJ, Skanes AC, et al. Predicting the cause of syncope from clinical history in patients undergoing prolonged monitoring. Heart Rhythm. 2009;6(2):238-243
  6. Quinn J, McDermott D. Electrocardiogram findings in emergency department patients with syncope. Acad Emerg Med. 2011;18(7):714-718
  7. Thiruganasambandamoorthy V, Hess EP, Turko E, et al. Defining abnormal electrocardiography in adult emergency department syncope patients: the Ottawa Electrocardiographic Criteria. CJEM. 2012;14(4):248-258
  8. Reed MJ, Newby DE, Coull AJ, et al. Diagnostic and prognostic utility of troponin estimation in patients presenting with syncope: a prospective cohort study. Emerg Med J. 2010; 27(4):272-276
  9. Reed MJ, Mills NL, Weir CJ. Sensitive troponin assay predicts outcome in syncope. Emerg Med J. 2012;29(12):1001- 1003
  10. Prandoni P, Lensing AW, Prins MH, Ciammaichella M, Perlati M, Mumoli N, Bucherini E, Visonà A, Bova C, Imberti D, Campostrini S, Barbar S; PESIT Investigators. Prevalence of Pulmonary Embolism among Patients Hospitalized for Syncope. N Engl J Med. 2016 Oct 20;375(16):1524-1531. PubMed PMID: 27797317.
  11. Prevalence Of Pulmonary Embolism In Patients Presenting With Syncope: A Systematic Review And Meta-Analysis Oqab, Z., et al, Am J Emerg Med 36(4):551, April 2018
  12. Huff JS, Decker WW, Quinn JV et al. Clinical policy: critical issues in the evaluation and management of adult patients presenting to the emergency department with syncope. Ann Emerg Med. 2007;49(4):431-444