A PHP Error was encountered

Severity: 8192

Message: Non-static method Low_search_model::load_models() should not be called statically, assuming $this from incompatible context

Filename: low_search/base.low_search.php

Line Number: 279

A PHP Error was encountered

Severity: 8192

Message: Non-static method Low_title::usage() should not be called statically, assuming $this from incompatible context

Filename: low_title/pi.low_title.php

Line Number: 9

Thromboembolic Disease – Diagnostic Tools

Diagnostic Tools

A number of approaches and investigations can be used to diagnose thromboembolic disease, which vary depending on the location of the disease. A combination of clinical decision rules and physical testing is frequently involved.


Diagnostic algorithms

Clinical decision rules can be used to assess the probability of developing a deep venous thrombosis (DVT) or pulmonary embolism (PE). The most commonly used rules are the:

  • Wells score for DVT and PE
    • not validated for use in patients with previous DVT, DVT in sites other than the lower limb, hospitalized patients or pregnant women
       
  • Geneva score and revised Geneva score1 for PE
    • standardized and based on clinical variables. It has sustained internal and external validation
       

Spiral (helical) computed tomography (CT) scanning2,3

CT can detect pulmonary emboli directly and is the only test that can provide extensive diagnostic information or an alternate diagnosis. Advances in multidetector technology, and the combined use of CT scan and angiography/venography, have markedly improved detection of deep emboli. Because of its sensitivity, pulmonary CT angiography is recommended for the majority of cases of suspected PE. There is evidence to suggest that this test is more cost effective than other diagnostic approaches.


Contrast venography, venous ultrasonography and magnetic resonance (MR) venography

Traditionally, contrast angiography/venography was used as the standard method for evaluating thromboses. However, in recent years, advances in ultrasonography have reduced the need for such invasive procedures. Ultrasonography is not suitable in all cases, however, as its sensitivity is reduced when imaging deeper venous areas.4



In general, contrast venography is still appropriate where patients have experienced prior DVT, or if clinical findings/ ultrasonography are inconclusive or disagree.

MR can provide highly accurate images, similar to those of contrast venography, in a noninvasive fashion. It is particularly useful in the iliac, femoral, popliteal, and calf muscle veins. MR venography is much less reliable in the tibial or peroneal veins.5


Chest radiography and ventilation-perfusion lung scan

Chest radiography is nonspecific for thromboembolic disease, but may be used as part of the diagnostic work-up when signs and symptoms are suggestive of a PE. Ventilation-perfusion (V/Q) scanning can be used after chest radiography, with results classifying the risk of thromboembolic disease as high, moderate or low. Whilst high-rated results have shown good predictive value for PE, low- or intermediate-probability V/Q scans appear to be insufficient to make diagnosis.6,7

D-dimer test

The D-dimer test detects thromboses via identification of the degradation products of cross‑linked fibrin. The test is usually positive in patients with thromboembolic disease; however, false-positives are possible as D-dimer levels may also be elevated in other conditions.

Newer latex agglutination and rapid enzyme-linked immunosorbent D-dimer assays have very high negative predictive values for thromboembolism and seem to have overcome the shortcomings of older assays.8,9 These tests may therefore help to identify patients with suspected thromboembolic disease who require further imaging investigations.


Biomarkers

Although assessment of biomarkers is not currently part of standard diagnostic procedures, recent evidence suggests that biomarkers of endothelial dysfunction, coagulation and tissue fibrosis may be useful in identifying individuals at risk of developing venous thromboembolic disease.10



 

References

  1. Le Gal G, Righini M, Roy PM, et al. Prediction of pulmonary embolism in the emergency department: the revised Geneva score. Ann Intern Med. 2006;144(3):165-171.
  2. Qanadli SD, Hajjam ME, Mesurolle B, et al. Pulmonary embolism detection: prospective evaluation of dual-section helical CT versus selective pulmonary arteriography in 157 patients. Radiology. 2000;217:447–455.
  3. Loud PA, Grossman ZD, Klippenstein DL, Ray CE. Combined CT venography and pulmonary angiography: a new diagnostic technique for suspected thromboembolic disease. AJR. 1998;170:951–954.
  4. Kearon C, Julian JA, Newman TE, Ginsberg JS. Noninvasive diagnosis of deep venous thrombosis. McMaster Diagnostic Imaging Practice Guideline Initiative. Ann Intern Med. 1998;128:663–677.
  5. Cantwell CP, Cradock A, Bruzzi J, et al. MR Venography with True Fast Imaging with Steady-state Precession for Suspected Lowerlimb Deep Vein Thrombosis. J Vasc Interv Radiol. 2006;17(11 Pt 1):1763-1769.
  6. PIOPED Investigators. Value of the ventilation/perfusion scan in acute pulmonary embolism: results of the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED). JAMA. 1990;263:2753–2759.
  7. van Beek EJ, Kuijer PM, Büller HR, Brandjes DP, Bossuyt PM, ten Cate JW. The clinical course of patients with suspected pulmonary embolism. Arch Intern Med. 1997;157:2593–2598.
  8. Burkill GJ, Bell JR, Chinn RJ, et al. The use of a D-dimer assay in patients undergoing CT pulmonary angiography for suspected pulmonary embolism. Clin Radiol. 2002;57:41–46.
  9. Irwin GA, Luchs JS, Donovan V, Katz DS. Can a state-of-the-art D-dimer test be used to determine the need for CT imaging in patients suspected of having pulmonary embolism? Acad Radiol. 2002;9:1013–1017.
  10. Musselwhite LW, Sheikh V, Norton TD, et al. Markers of endothelial dysfunction, coagulation and tissue fibrosis independently predict venous thromboembolism in HIV. AIDS. 2011;25(6):787–795.