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| {{Deep vein thrombosis}} | | {{Deep vein thrombosis}} |
| ==Pre-test probability==
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| In a patient with suspected [[DVT]], establishing pre-test probability helps in early risk stratification and appropriate use of laboratory tests and imaging modalities. Many pretest probability scoring system are proposed for use in primary care patients, like Wells score, Hamilton score , and AMUSE score. <ref name="pmid16357403">{{cite journal |author=Subramaniam RM, Chou T, Heath R, Allen R |title=Importance of pretest probability score and D-dimer assay before sonography for lower limb deep venous thrombosis |journal=AJR Am J Roentgenol |volume=186 |issue=1 |pages=206–12 |year=2006 |month=January |pmid=16357403|doi=10.2214/AJR.04.1398 |url=http://www.ajronline.org/cgi/pmidlookup?view=long&pmid=16357403 |accessdate=2011-12-22}}</ref><ref name="pmid21242558">{{cite journal |author=van der Velde EF, Toll DB, Ten Cate-Hoek AJ, Oudega R, Stoffers HE, Bossuyt PM, Büller HR, Prins MH, Hoes AW, Moons KG, van Weert HC|title=Comparing the diagnostic performance of 2 clinical decision rules to rule out deep vein thrombosis in primary care patients |journal=Ann Fam Med|volume=9 |issue=1 |pages=31–6 |year=2011 |pmid=21242558 |pmc=3022042 |doi=10.1370/afm.1198 |url=http://www.annfammed.org/cgi/pmidlookup?view=long&pmid=21242558 |accessdate=2011-12-22}}</ref> When combined with pretest probability, ultrasonography and D-dimer tests are most useful in diagnosis for DVT.
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| ===Wells Score===
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| Wells score is the most widely used tool to assess pre-test probability. It includes 10 clinical questions, with the score ranging from -2 to 9.
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| '''[[Wells score Calculator for DVT]]'''
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| {| class=wikitable border=1
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| !Variable
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| !Wells<ref name="pmid9428249">{{cite journal |author=Wells PS, Anderson DR, Bormanis J, ''et al.'' |title=Value of assessment of pretest probability of deep-vein thrombosis in clinical management |journal=Lancet |volume=350 |issue=9094 |pages=1795–8 |year=1997 |pmid=9428249 |doi=10.1016/S0140-6736(97)08140-3 |url=}}</ref><ref name="pmid14507948">{{cite journal |author=Wells PS, Anderson DR, Rodger M, ''et al.'' |title=Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis |journal=N. Engl. J. Med. |volume=349 |issue=13 |pages=1227–35 |year=2003 |month=September |pmid=14507948 |doi=10.1056/NEJMoa023153 |url=}}</ref>
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| |Active cancer (treatment within last 6 months or palliative)
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| |style="text-align:center"|1
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| |Calf swelling >3 cm compared to other calf (measured 10 cm below tibial tuberosity)
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| |style="text-align:center"|1
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| |Collateral superficial veins (non-varicose)
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| |style="text-align:center"|1
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| |Pitting edema (confined to symptomatic leg)
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| |style="text-align:center"|1
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| |Swelling of entire leg
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| |style="text-align:center"|1
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| |Localized pain along distribution of deep venous system
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| |style="text-align:center"|1
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| |Paralysis, paresis, or recent cast immobilization of lower extremities
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| |style="text-align:center"|1
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| |Recently bedridden > 3 days, or major surgery requiring regional or general anesthetic in past 12 weeks
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| |style="text-align:center"|1
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| |Previously documented DVT
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| |style="text-align:center"|1
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| |Alternative diagnosis at least as likely
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| |style="text-align:center"| - 2
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| |-
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| |}
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| ====Interpretation====
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| * High probability: ≥ 3 (Prevalence of DVT - 53%)
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| * Moderate probability: 1-2 (Prevalence of DVT - 17%)
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| * Low probability: ≤ 0 (Prevalence of DVT - 5%)
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| A modified scoring system stratifies the patients as likely (≥ 2, 28% prevalence) or unlikely (< 2, 6% prevalence) based on the score of 2.
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| ===Limitations of Wells score===
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| * The accuracy of the Wells rule, though useful in secondary and tertiary care centers, has not been properly validated for use in primary care patients with the suspicion of DVT.<ref name="pmid16027451">{{cite journal |author=Oudega R, Hoes AW, Moons KG |title=The Wells rule does not adequately rule out deep venous thrombosis in primary care patients |journal=Ann. Intern. Med. |volume=143 |issue=2 |pages=100–7 |year=2005 |month=July |pmid=16027451 |doi=|url=http://www.annals.org/cgi/pmidlookup?view=long&pmid=16027451 |accessdate=2011-12-22}}</ref>
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| * The performance of Wells score was decreased when evaluating elderly patients or those with a prior DVT or having those having other comorbidities, which might be equivalent to what is found in a primary care setting.<ref name="pmid16027455">{{cite journal |author=Goodacre S, Sutton AJ, Sampson FC|title=Meta-analysis: The value of clinical assessment in the diagnosis of deep venous thrombosis |journal=Ann. Intern. Med. |volume=143 |issue=2|pages=129–39 |year=2005 |month=July |pmid=16027455 |doi= |url=http://www.annals.org/cgi/pmidlookup?view=long&pmid=16027455 |accessdate=2011-12-22}}</ref><ref name="pmid17261865">{{cite journal |author=Qaseem A, Snow V, Barry P, Hornbake ER, Rodnick JE, Tobolic T, Ireland B, Segal J, Bass E, Weiss KB, Green L, Owens DK |title=Current diagnosis of venous thromboembolism in primary care: a clinical practice guideline from the American Academy of Family Physicians and the American College of Physicians |journal=Ann Fam Med |volume=5 |issue=1 |pages=57–62 |year=2007 |pmid=17261865 |pmc=1783928 |doi=10.1370/afm.667|url=http://www.annfammed.org/cgi/pmidlookup?view=long&pmid=17261865 |accessdate=2011-12-22}}</ref> Also, it should be highlighted that Wells criteria is an additional tool to diagnosis rather than being a stand-alone test.
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| ==Value of screening== | | ==Value of screening== |