Pulmonary embolism -- Meyer et al. 340 c1421 -- BMJ 2010

 
Geneva revised score Wells score
Variables Points Variables Points
Predisposing factors
Age >65 years 1 – –
Previous venous thromboembolism 3 Previous DVT or PE 1.5
Surgery or fracture <1 month 2 Recent surgery or immobilisation 1.5
Active malignancy 2 Cancer 1
Symptoms
Unilateral lower limb pain 3 – –
Haemoptysis 2 Haemoptysis 1
Clinical signs
Heart rate 75-94 bpm 3 – –
Heart rate ≥95 bpm 5 Heart rate >100 beats/min 1.5
Unilateral lower limb oedema and pain 4 Clinical signs of DVT 3
– – Alternative diagnosis less likely than PE 3
Clinical probability
Low 0-3 Low 0-1
Intermediate 4-10 Intermediate 2-6
High ≥11 High ≥7

DVT=deep vein thrombosis, PE=pulmonary embolism.

 

Investigations

  • Plasma D-dimer measurement is the next step for most outpatients. D-dimer levels are raised in many situations and a positive test result is non-specific. However, based on a negative likelihood ratio of 0.08, a negative result for a quantitative, enzyme linked immunosorbent assay (ELISA) D-dimer test excludes pulmonary embolism and the need for further testing in about 30% of patients, provided that the clinical probability is low or moderate.11 Quantitative latex based and whole blood qualitative D-dimer assays have a negative likelihood ratio of 0.20 to 0.30 and allow exclusion of pulmonary embolism only in patients with a low clinical probability.11 In patients with a high clinical probability, no D-dimer test is sensitive enough to rule out pulmonary embolism.
     
  • Refer patients with a positive D-dimer test for multidetector spiral computed tomography. This procedure confirms pulmonary embolism when an intraluminal defect is seen in several subsegmental arteries or in a more proximal pulmonary artery. A ventilation and perfusion lung scan may be selected when multidetector spiral computed tomography is contraindicated (renal failure, allergy to contrast medium) but yields a high rate of inconclusive results. Finally, compression ultrasonography of the leg veins showing a proximal deep vein thrombosis in a patient with thoracic symptoms allows confirmation of pulmonary embolism without further testing, but has a low diagnostic yield, except in patients with clinical symptoms of deep vein thrombosis.9 11
     
  • Excluding pulmonary embolism on inappropriate criteria, for example, low D-dimer reading in a patient with a high clinical probability or a low probability lung scan in a patient with a high clinical probability, exposes patients to an increase risk of it recurring and death.