Acute pulmonary embolism: diagnostic tool
PERC rule, D-dimer, Well's score, Revised Geneva score
PERC rule for Pulmonary Embolism
This is used when it seems unlikely (pre-test probability ≤15%) but you want to exclude PE.
Result
There is less than a 2% chance of PE. Therefore, no additional tests are necessary.
If the clinician's pre-test probability is less than 15% and no criteria are positive, then the PERC Rule criteria are met.
Well's score
Classic Well's score
Low
Intermediate
High
PE unlikely
PE likely
Simplified Well's score
Low
Intermediate
High
PE unlikely
PE likely
Revised Geneva Score
Low
Intermediate
High
D-dimer (Age-adjusted cut-off value)
The D-dimer test cut-off value is 0.5 ng/mL or 500 mg/L (some hospitals use mg/L as the unit).
Age-adjusted cut-off value
calculated by adding 10 times the age over 50 to the standard cut-off value. For example, if the patient is 55 years old, the cut-off value would be 550 ng/mL.
Cut-off: 500 ng/ml (0.5 mg/L)
A reliable method for diagnosis is to use the ELISA technique for D-dimer to achieve high sensitivity, which can exclude acute pulmonary embolism in low-probability patients.
Method | Time | Sensitivity (%) | Specificity (%) |
|---|---|---|---|
Erythrocyte agglutination assay | 2 min | 82 | |
Semi quantitative latex | 5 min | 86 | |
Enzyme Linked Immunosorbent Assay (ELISA) | > 8 hours | 95 | 46 - 68% |
Quantitative Rapid ELISA | 30 min | ||
Semi quantitative rapid ELISA | 10 min | ||
Qualitative rapid ELISA | 10 min | 90 | |
Quantitative latex agglutination assay | 10 - 15 min |
References
1) Kline JA, Mitchell AM, Kabrhel C, Richman PB, Courtney DM. Clinical criteria to prevent unnecessary diagnostic testing in emergency department patients with suspected pulmonary embolism. J Thromb Haemost. 2004 Aug;2(8):1247-55. doi: 10.1111/j.1538-7836.2004.00790.x. PMID: 15304025.
2) Wells PS, Anderson DR, Rodger M, Stiell I, Dreyer JF, Barnes D, Forgie M, Kovacs G, Ward J, Kovacs MJ. Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and d-dimer. Ann Intern Med. 2001 Jul 17;135(2):98-107. doi: 10.7326/0003-4819-135-2-200107170-00010. PMID: 11453709.
3) Schouten H J, Geersing G J, Koek H L, Zuithoff N P A, Janssen K J M, Douma R A et al. Diagnostic accuracy of conventional or age adjusted D-dimer cut-off values in older patients with suspected venous thromboembolism: systematic review and meta-analysis BMJ 2013; 346 :f2492 doi:10.1136/bmj.f2492
4) Le Gal G, Righini M, Roy PM, Sanchez O, Aujesky D, Bounameaux H, Perrier A. Prediction of pulmonary embolism in the emergency department: the revised Geneva score. Ann Intern Med. 2006 Feb 7;144(3):165-71. doi: 10.7326/0003-4819-144-3-200602070-00004. PMID: 16461960.