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| ==Diagnosis== | | ==Diagnosis== |
| The diagnosis of PE is based primarily on validated clinical criteria combined with selective testing because the typical clinical presentation ([[shortness of breath]], [[chest pain]]) cannot be definitively differentiated from other causes of chest pain and shortness of breath. The decision to do medical imaging is usually based on clinical grounds, i.e. the [[medical history]], symptoms and findings on [[physical examination]], followed by an assessment of clinical probability.<ref name=Goldhaber/> | | The diagnosis of PE is based primarily on validated clinical criteria combined with selective testing because the typical clinical presentation ([[shortness of breath]], [[chest pain]]) cannot be definitively differentiated from other causes of chest pain and shortness of breath. The decision to do medical imaging is usually based on clinical grounds, i.e. the [[medical history]], symptoms and findings on [[physical examination]], followed by an assessment of clinical probability.<cite>Goldhaber</cite> |
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| The most commonly used method to predict clinical probability, the Wells score, is a [[clinical prediction rule]], whose use is complicated by multiple versions being available. In 1995, Wells ''et al.'' initially developed a prediction rule (based on a literature search) to predict the likelihood of PE, based on clinical criteria.<ref name=pmid7752753>{{cite journal |author=Wells PS, Hirsh J, Anderson DR, Lensing AW, Foster G, Kearon C, Weitz J, D'Ovidio R, Cogo A, Prandoni P |title=Accuracy of clinical assessment of deep-vein thrombosis |journal=Lancet |volume=345 |issue=8961 |pages=1326–30 |year=1995 |pmid=7752753 |doi=10.1016/S0140-6736(95)92535-X}}</ref> The prediction rule was revised in 1998<ref name=pmid9867786>{{cite journal |author=Wells PS, Ginsberg JS, Anderson DR, Kearon C, Gent M, Turpie AG, Bormanis J, Weitz J, Chamberlain M, Bowie D, Barnes D, Hirsh J |title=Use of a clinical model for safe management of patients with suspected pulmonary embolism |journal=Ann Intern Med |volume=129 |issue=12 |pages=997–1005 |year=1998 |pmid=9867786 |last12=Hirsh |first12=J}}</ref> This prediction rule was further revised when simplified during a validation by Wells ''et al.'' in 2000.<ref name=pmid10744147>{{cite journal | author = Wells P, Anderson D, Rodger M, Ginsberg J, Kearon C, Gent M, Turpie A, Bormanis J, Weitz J, Chamberlain M, Bowie D, Barnes D, Hirsh J | title = Derivation of a simple clinical model to categorize patients probability of pulmonary embolism: increasing the models utility with the SimpliRED D-dimer | journal = Thromb Haemost | volume = 83 | issue = 3 | pages = 416–20 | year = 2000 | pmid = 10744147 | last12 = Barnes | first12 = D | last13 = Hirsh | first13 = J}}</ref> In the 2000 publication, Wells proposed two different scoring systems using cutoffs of 2 or 4 with the same prediction rule.<ref name=pmid10744147/> In 2001, Wells published results using the more conservative cutoff of 2 to create three categories.<ref name=pmid11453709>{{cite journal |author=Wells PS, Anderson DR, Rodger M, Stiell I, Dreyer JF, Barnes D, Forgie M, Kovacs G, Ward J, Kovacs MJ |title=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 |journal=Ann Intern Med |volume=135 |issue=2 |pages=98–107 |year=2001 |pmid=11453709 | url=http://www.annals.org/cgi/content/full/135/2/98}}</ref> An additional version, the "modified extended version", using the more recent cutoff of 2 but including findings from Wells's initial studies<ref name=pmid7752753/><ref name=pmid9867786/> were proposed.<ref name=pmid10739372>{{cite journal |author=Sanson BJ, Lijmer JG, Mac Gillavry MR, Turkstra F, Prins MH, Büller HR |title=Comparison of a clinical probability estimate and two clinical models in patients with suspected pulmonary embolism. ANTELOPE-Study Group |journal=Thromb. Haemost. |volume=83 |issue=2 |pages=199–203 |year=2000 |pmid=10739372}}</ref> Most recently, a further study reverted to Wells's earlier use of a cutoff of 4 points<ref name=pmid10744147/> to create only two categories.<ref name=pmid16403929>{{cite journal |author=van Belle A, Büller H, Huisman M, Huisman P, Kaasjager K, Kamphuisen P, Kramer M, Kruip M, Kwakkel-van Erp J, Leebeek F, Nijkeuter M, Prins M, Sohne M, Tick L |title=Effectiveness of managing suspected pulmonary embolism using an algorithm combining clinical probability, D-dimer testing, and computed tomography |journal=JAMA |volume=295 |issue=2 |pages=172–9 |year=2006 |pmid=16403929 | url=http://jama.ama-assn.org/cgi/content/full/295/2/172 | doi=10.1001/jama.295.2.172 |last12=Prins |first12=MH |last13=Sohne |first13=M |last14=Tick |first14=LW |last15=Christopher Study |first15=Investigators}}</ref> | | The most commonly used method to predict clinical probability, the Wells score, is a [[clinical prediction rule]], whose use is complicated by multiple versions being available. In 1995, Wells ''et al.'' initially developed a prediction rule (based on a literature search) to predict the likelihood of PE, based on clinical criteria.<cite>REFNAME1</cite> The prediction rule was revised in 1998 <cite>REFNAME2</cite> This prediction rule was further revised when simplified during a validation by Wells ''et al.'' in 2000. <cite>REFNAME3</cite> In the 2000 publication, Wells proposed two different scoring systems using cutoffs of 2 or 4 with the same prediction rule. <cite>REFNAME3</cite> In 2001, Wells published results using the more conservative cutoff of 2 to create three categories.<cite>REFNAME4</cite> An additional version, the "modified extended version", using the more recent cutoff of 2 but including findings from Wells's initial studies<cite>REFNAME5</cite> <cite>REFNAME6</cite> were proposed. <cite>REFNAME7</cite> Most recently, a further study reverted to Wells's earlier use of a cutoff of 4 points <cite>REFNAME3</cite> to create only two categories. <cite>REFNAME8</cite> |
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| There are additional prediction rules for PE, such as the [[Geneva score|Geneva rule]]. More importantly, the use of ''any'' rule is associated with reduction in recurrent thromboembolism.<ref name=pmid16461959>{{cite journal |author=Roy PM, Meyer G, Vielle B, Le Gall C, Verschuren F, Carpentier F, Leveau P, Furber A |title=Appropriateness of diagnostic management and outcomes of suspected pulmonary embolism |journal=Ann. Intern. Med. |volume=144 |issue=3 |pages=157–64 |year=2006 |pmid=16461959}}</ref> | | There are additional prediction rules for PE, such as the [[Geneva score|Geneva rule]]. More importantly, the use of ''any'' rule is associated with reduction in recurrent thromboembolism. <cite>REFNAME9</cite> |
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| ''The Wells score'':<ref name=pmid12952389>{{cite journal |author=Neff MJ |title=ACEP releases clinical policy on evaluation and management of pulmonary embolism |journal=American Family Physician |volume=68 |issue=4 |pages=759–60 |year=2003 |pmid=12952389 |doi=|url=http://www.aafp.org/afp/20030815/practice.html }} {{dead link|date=March 2010}}</ref> | | ''The Wells score'': <cite>REFNAME10</cite> |
| *clinically suspected [[DVT]] - 3.0 points | | *clinically suspected [[DVT]] - 3.0 points |
| *alternative diagnosis is less likely than PE - 3.0 points | | *alternative diagnosis is less likely than PE - 3.0 points |
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| *malignancy (treatment for within 6 months, palliative) - 1.0 points | | *malignancy (treatment for within 6 months, palliative) - 1.0 points |
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| Traditional interpretation<ref name=pmid10744147/><ref name=pmid11453709/><ref name=pmid17874979>{{cite journal |author=Yap KS, Kalff V, Turlakow A, Kelly MJ |title=A prospective reassessment of the utility of the Wells score in identifying pulmonary embolism |journal=Med. J. Aust. |volume=187 |issue=6 |pages=333–6 |year=2007 |pmid=17874979 |doi=}}</ref> | | Traditional interpretation <cite>REFNAME3</cite><cite>REFNAME4</cite> <cite>REFNAME11</cite> |
| * Score >6.0 - High (probability 59% based on pooled data<ref name=pmid17185658>{{cite journal |author=Stein PD, Woodard PK, Weg JG, Wakefield TW, Tapson VF, Sostman HD, Sos TA, Quinn DA, Leeper KV, Hull RD, Hales CA, Gottschalk A, Goodman LR, Fowler SE, Buckley JD |title=Diagnostic pathways in acute pulmonary embolism: recommendations of the PIOPED II Investigators |journal=Radiology |volume=242 |issue=1 |pages=15–21 |year=2007 |doi=10.1148/radiol.2421060971 | pmid=17185658 |last12=Gottschalk |first12=A |last13=Goodman |first13=LR |last14=Fowler |first14=SE |last15=Buckley |first15=JD |last16=Pioped Ii |first16=Investigators}}</ref>) | | * Score >6.0 - High (probability 59% based on pooled data <cite>REFNAME12</cite>) |
| * Score 2.0 to 6.0 - Moderate (probability 29% based on pooled data<ref name=pmid17185658/>) | | * Score 2.0 to 6.0 - Moderate (probability 29% based on pooled data <cite>REFNAME12</cite>) |
| * Score <2.0 - Low (probability 15% based on pooled data<ref name=pmid17185658/>) | | * Score <2.0 - Low (probability 15% based on pooled data <cite>REFNAME12</cite>) |
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| Alternative interpretation<ref name=pmid10744147/><ref name=pmid16403929/> | | Alternative interpretation <cite>REFNAME3</cite><cite>REFNAME8</cite> |
| * Score > 4 - PE likely. Consider diagnostic imaging. | | * Score > 4 - PE likely. Consider diagnostic imaging. |
| * Score 4 or less - PE unlikely. Consider [[D-dimer]] to rule out PE. | | * Score 4 or less - PE unlikely. Consider [[D-dimer]] to rule out PE. |
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| ===Blood tests=== | | ===Blood tests=== |
| Early primary research has shown that in low/moderate suspicion of PE, a normal [[D-dimer]] level (shown in a [[blood test]]) is enough to exclude the possibility of thrombotic PE.<ref name=pmid8165626>{{cite journal |author=Bounameaux H, de Moerloose P, Perrier A, Reber G |title=Plasma measurement of D-dimer as diagnostic aid in suspected venous thromboembolism: an overview |journal=Thromb. Haemost. |volume=71 |issue=1 |pages=1–6 |year=1994 |pmid=8165626 |doi=}}</ref> This has been corroborated by a recent [[systematic review]] of studies of patients with low [[clinical utility of diagnostic tests|pre-test probability]] (PTP) of PE and negative [[D-dimer]] results that found the three month risk of thromboembolic events in patients excluded in this manner was 0.14%, with [[confidence interval|95% confidence intervals]] from 0.05 to 0.41%, though this review was limited by its use of only one [[randomized controlled trial|randomized-controlled clinical trial]], the remainder of studies being [[prospective cohort study|prospective cohorts]].<ref>{{cite journal |author=Carrier M, Righini M, Djurabi RK, ''et al.'' |title=VIDAS D-dimer in combination with clinical pre-test probability to rule out pulmonary embolism. A systematic review of management outcome studies |journal=Thromb. Haemost. |volume=101 |issue=5 |pages=886–92 |year=2009 |month=May |pmid=19404542 |doi=10.1160/TH-08-10-0689}}</ref> D-dimer is highly sensitive but not very specific (specificity around 50%). In other words, a positive D-dimer is not synonymous with PE, but a negative D-dimer is, with a good degree of certainty, an indication of absence of a PE.<ref>{{cite journal |author=Schrecengost JE, LeGallo RD, Boyd JC, ''et al.'' |title=Comparison of diagnostic accuracies in outpatients and hospitalized patients of D-dimer testing for the evaluation of suspected pulmonary embolism |journal=Clin. Chem. |volume=49 |issue=9 |pages=1483–90 |year=2003 |month=September |pmid=12928229 |doi= 10.1373/49.9.1483|url=http://www.clinchem.org/cgi/content/full/49/9/1483}}</ref> | | Early primary research has shown that in low/moderate suspicion of PE, a normal [[D-dimer]] level (shown in a [[blood test]]) is enough to exclude the possibility of thrombotic PE. <cite>REFNAME13</cite> This has been corroborated by a recent [[systematic review]] of studies of patients with low [[clinical utility of diagnostic tests|pre-test probability]] (PTP) of PE and negative [[D-dimer]] results that found the three month risk of thromboembolic events in patients excluded in this manner was 0.14%, with [[confidence interval|95% confidence intervals]] from 0.05 to 0.41%, though this review was limited by its use of only one [[randomized controlled trial|randomized-controlled clinical trial]], the remainder of studies being [[prospective cohort study|prospective cohorts]]. <cite>REFNAME14</cite> D-dimer is highly sensitive but not very specific (specificity around 50%). In other words, a positive D-dimer is not synonymous with PE, but a negative D-dimer is, with a good degree of certainty, an indication of absence of a PE. <cite>REFNAME15</cite> |
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| When a PE is being suspected, a number of [[blood test]]s are done, in order to exclude important secondary causes of PE. This includes a [[full blood count]], [[coagulation|clotting status]] ([[prothrombin time|PT]], [[aPTT]], [[thrombin time|TT]]), and some screening tests ([[erythrocyte sedimentation rate]], [[renal function]], [[liver enzyme]]s, [[electrolyte]]s). If one of these is abnormal, further investigations might be warranted. | | When a PE is being suspected, a number of [[blood test]]s are done, in order to exclude important secondary causes of PE. This includes a [[full blood count]], [[coagulation|clotting status]] ([[prothrombin time|PT]], [[aPTT]], [[thrombin time|TT]]), and some screening tests ([[erythrocyte sedimentation rate]], [[renal function]], [[liver enzyme]]s, [[electrolyte]]s). If one of these is abnormal, further investigations might be warranted. |