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Combining clinical probability and ventilation-perfusion scan for diagnosis of pulmonary embolism
  1. Kerstin Hogg, Clinical Research Fellow,
  2. Ged Brown, Specialist Registrar
  1. Department of Emergency Medicine, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WL, UK;


    A short cut review was carried out to establish whether clinical probability estimates improve the utility of VQ scan results in patients being investigated for possible pulmonary embolus. Altogether 387 papers were found using the reported search, of which six presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these best papers are tabulated. A clinical bottom line is stated.

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    Kerstin Hogg, Clinical Research Fellow
 Ged Brown, Specialist Registrar

    Clinical scenario

    A 20 year old woman presents to the emergency department with shortness of breath and chest pain. Her D-dimer level is abnormal and you have sent her for a ventilation-perfusion scan. The scan result is reported as “low probability for pulmonary embolic disease, however this does not rule out pulmonary embolism”. You have assigned her a low clinical probability of pulmonary embolism score and wonder if this helps interpret the scan.

    Three part question

    In [patients who have undergone ventilation-perfusions scans for possible pulmonary embolus] does [combining clinical probability of pulmonary embolism and ventilation-perfusion scan result] increase the [diagnostic utility]?

    Search strategy

    Medline using the OVID interface 1966-07/03. [exp pulmonary embolism/ OR pulmonary embol$.mp. OR OR exp thromboembolism/ OR pulmonary infarct$.mp.] AND [exp nuclear medicine/ OR exp ventilation-perfusion ratio/ OR OR ventilation OR OR lung] AND [exp Risk Assessment/ OR risk OR risk OR] LIMIT to human AND English.

    Search outcome

    Altogether 387 papers found of which six addressed the question and are shown in table 3.

    Table 3


    All ventilation-perfusion scans must be interpreted with an independent clinical probability score.

    Kerstin Hogg, Clinical Research Fellow
 Ged Brown, Specialist Registrar


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