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| ==Overview== | | ==Overview== |
| Signs and symptoms of pulmonary embolism are nonspecific; therefore, patients presenting with:
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| *Unexplained [[dyspnea]]
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| *[[Tachypnea]]
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| *[[Chest pain]]
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| *Risk factors for pulmonary embolism
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| —should undergo diagnostic tests until the diagnosis is confirmed or eliminated or an alternative diagnosis is made.
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| == CT equipped hospitals == | | ==Computed Tomography== |
| In hospitals having experience in performing and interpreting CT Pulmonary angiography, following flowchart approach can be adopted.
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| {{familytree/start |summary=PE diagnosis Algorithm.}}
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| {{familytree | | | | | | | | GMa | GMa='''Determine chances of PE'''}}
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| {{familytree | | | | |,|-|-|-|^|-|-|-|-|.| | | }}
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| {{familytree | | |JOE| | | | | | | |SIS| | | JOE='''Low chance'''|SIS='''High chance'''}}
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| {{familytree | | | |!| | | | | | | | | |!| }}
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| {{familytree | | |MOM| | | | | | | | |!| |MOM='''[[D-dimer]]'''}}
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| {{familytree | |,|-|^|.| | | | | | | | |!| }}
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| {{familytree |GPa| |JOE|~|~|~|~|~|MOM|GPa='''<500 ng/ml'''|JOE='''>500 ng/ml'''|MOM='''[[Pulmonary embolism other imaging findings#Angiography|CT Pulmonary angiography]]'''}}
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| {{familytree | |!| | | | | | | | | |,|-|^|.| }}
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| {{familytree |MOM| | | | | | |SIS| | |GMa|MOM='''PE excluded'''|SIS=Negative|GMa=Positive}}
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| {{familytree | | | | | | | | | | |!| | | | |!| }}
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| {{familytree | | | | | | | | | |SIS| | |GMa|SIS='''PE excluded'''|GMa='''PE confirmed'''}}
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| {{familytree/end}}
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| ==CT Non-equipped hospitals==
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| Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) Study proposed the following for hospitals who do not have sufficient resources to perform or interpret CT Pulmonary angiography.
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| Wells criteria are used to assess the clinical probability of PE and its graded as Low, Intermediate or High. Later a ventilation-perfusion scan (V/Q) is performed, and based on the result of the scan PE is diagnosed.
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| '''The following table summarizes the possible outcome of V/Q scan:'''
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| {| border="1"
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| |+
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| ! [[Pulmonary embolism ventilation/perfusion scan|V/Q Scan]] !! [[Pulmonary embolism diagnosis#Wells score|Clinical Probability]] !! Diagnosis
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| |-
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| | Normal
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| | any probability
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| | PE excluded
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| |-
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| | Low probability scan
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| | Low
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| | PE excluded
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| |-
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| | High probability scan
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| | High
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| | PE confirmed
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| |-
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| | Variable result/Non diagnostic
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| | Variable
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| | Serial [[Deep vein thrombosis ultrasound|lower extremity USG]] or [[Pulmonary embolism other imaging findings#Angiography|Pulmonary angiography]]
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| |}
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| ==Low risk outpatient population==
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| In populations with low PE prevalence, to avoid unnecessary and costly diagnostic interventions, the following factors were proposed, that formed the PE Rule-out Criteria('''PERC'''):
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| *Age less than 50 years
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| *Heart rate less than 100 bpm
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| *Oxyhemoglobin saturation ≥95 percent
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| *No hemoptysis
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| *No estrogen use
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| *No prior DVT or PE
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| *No unilateral leg swelling
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| *No surgery or trauma requiring hospitalization within the past four weeks.
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| This approach was tested in a multicenter study involving 8138 outpatients with suspected PE.<ref name="pmid18318689">{{cite journal |author=Kline JA, Courtney DM, Kabrhel C, Moore CL, Smithline HA, Plewa MC, Richman PB, O'Neil BJ, Nordenholz K |title=Prospective multicenter evaluation of the pulmonary embolism rule-out criteria |journal=J. Thromb. Haemost. |volume=6 |issue=5 |pages=772–80 |year=2008 |month=May |pmid=18318689 |doi=10.1111/j.1538-7836.2008.02944.x |url=http://dx.doi.org/10.1111/j.1538-7836.2008.02944.x |accessdate=2011-12-19}}</ref> Another study stated that the PERC-approach has a high negative predictive value and sensitivity when combined with a low probability of PE using the Wells criteria, but a low positive predictive value and specificity.<ref name="pmid18272098">{{cite journal |author=Wolf SJ, McCubbin TR, Nordenholz KE, Naviaux NW, Haukoos JS |title=Assessment of the pulmonary embolism rule-out criteria rule for evaluation of suspected pulmonary embolism in the emergency department |journal=Am J Emerg Med |volume=26 |issue=2 |pages=181–5 |year=2008 |month=February |pmid=18272098 |doi=10.1016/j.ajem.2007.04.026 |url=http://linkinghub.elsevier.com/retrieve/pii/S0735-6757(07)00307-5 |accessdate=2011-12-19}}</ref>
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| Therefore, it can be stated, when combined with a clinical assessment of low risk for PE, this approach can exclude PE without additional diagnostic testing. However, in clinical settings with a higher prevalence of PE (>20%), the PERC based approach has significantly poor predictive value. <ref name="pmid21091866">{{cite journal |author=Hugli O, Righini M, Le Gal G, Roy PM, Sanchez O, Verschuren F, Meyer G, Bounameaux H, Aujesky D |title=The pulmonary embolism rule-out criteria (PERC) rule does not safely exclude pulmonary embolism |journal=J. Thromb.Haemost. |volume=9 |issue=2 |pages=300–4 |year=2011 |month=February |pmid=21091866 |doi=10.1111/j.1538-7836.2010.04147.x |url=http://dx.doi.org/10.1111/j.1538-7836.2010.04147.x |accessdate=2011-12-19}}</ref>
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| ==References== | | ==References== |