Synopsis
Recognise pulmonary embolism promptly, choose the correct probability-led diagnostic branch, and distinguish physiological severity from suitability for carefully supported outpatient care.
- Assess haemodynamic stability before calculating any diagnostic or outpatient score: shock or persistent hypotension places the patient in the emergency high-risk branch.
- In non-pregnant adults with low overall clinical suspicion and a feasible alternative diagnosis, consider PERC; otherwise use two-level Wells: above 4 needs immediate CTPA, while 4 or less needs D-dimer, with interim therapeutic anticoagulation whenever the indicated test is delayed.
- Only physiologically low-risk patients should enter outpatient assessment, using a validated prognostic tool plus bleeding, comorbidity, social and follow-up checks.
Key red flags
Systolic hypotension, obstructive shock, syncope with ongoing compromise, or cardiac arrest requires an emergency PE pathway.
Severe or escalating hypoxaemia, altered consciousness, cold peripheries, oliguria or rising lactate indicates impaired right-heart output.
Active major bleeding, recent intracranial disease or recent major surgery materially changes anticoagulation and reperfusion choices.
Pregnancy, severe renal impairment or contrast allergy changes imaging selection but must not permit diagnostic drift or dangerous delay.
Persistent hypotension, shock, cardiac arrest, cool peripheries, confusion, oliguria or elevated lactate reflects inadequate output from acute right-ventricular pressure overload and mandates emergency escalation.
Investigation priorities
Select the NICE pre-test probability branch in non-pregnant adults before definitive thoracic imaging.
Management branches
Shock, persistent hypotension, cardiac arrest or rapidly worsening organ perfusion is present.
- Start monitored ABC resuscitation, summon senior critical-care and PE expertise, establish vascular access and avoid excessive fluid loading that may worsen right-ventricular distension.
- Obtain the fastest safe confirmation and right-heart assessment, begin continuous UFH for confirmed unstable PE when not contraindicated, and assess systemic thrombolysis immediately against bleeding hazards.
PE is clinically suspected in a non-pregnant adult without haemodynamic instability.