Pulmonary embolism — the diagnostic algorithm and the risk stratification

The diagnostic algorithm:

• Begin with the Wells score (this patient: PE unlikely at 1.5).^[1]
• In the low-risk PE-unlikely patient, apply the PERC rule — if all eight criteria negative, the PE is ruled out without testing. This patient is on the OCP, which fails the PERC oestrogen criterion, so the PERC does not rule out.^[1]
• Proceed to the D-dimer. The age-adjusted cutoff applies (for the patient below 50, the fixed 500). This patient is 45, so the cutoff is 500, and her 680 is positive.^[1][3]
• A positive D-dimer (or a likely PE) proceeds to the CT pulmonary angiography — the diagnostic test of choice for the stable patient.^[1]

The risk stratification (after the diagnosis):

• The high-risk (massive): the shock or the hypotension — reperfusion.^[1]
• The intermediate-risk (submassive): the normotensive with the right ventricular dysfunction (the echo or the CT) or the elevated biomarkers (the troponin, the BNP).^[1]
• The low-risk: the normotensive, no right ventricular dysfunction, the negative biomarkers — the anticoagulation, the risk-stratified outpatient.^[1]
• The PESI or the sPESI scores the 30-day mortality; the sPESI of zero identifies the low-risk.^[1]

The D-dimer: the high sensitivity, the low specificity — it rules out (the high negative predictive value) but it does not rule in. The age-adjusted cutoff (age times 10 for the patient above 50) improves the specificity in the elderly at a three-month failure rate of 0.3 per cent. It is never used in isolation in the high-risk patient.^[1][3]