Modified PIOPED criteria for diagnosis of pulmonary embolus

Dr Henry Knipe and Radswiki et al.

The modified PIOPED criteria for the diagnosis of pulmonary embolus (PE) determine the probability of pulmonary emboli following a VQ scan.


High probability
  • two or more large mismatched segmental defects or equivalent moderate/large defects with a normal x-ray
  • any perfusion defect substantially larger than the radiographic abnormality
Intermediate probability
  • multiple perfusion defects with associated radiographic opacities
  • >25% of a segment and less than two mismatched segmental perfusion defects with
    • normal radiograph
    • one moderate segmental
    • one large or two moderate segmental
    • one large and one moderate segmental
    • three moderate segmental
  • triple match: solitary moderate-large matching segmental defect with matching radiograph
  • difficult to characterize as high probability or low probability
  • single matched ventilation-perfusion defect with clear chest radiograph
    • this is considered borderline low/intermediate probability, but should be classified as intermediate in most circumstances by most readers, as described in Table 5 of Gottschalk article 1
Low probability
  • nonsegmental defects: small effusion, blunting costophrenic angle, cardiomegaly, elevated diaphragm, ectatic aorta
  • any perfusion defect with a substantially larger radiographic abnormality
  • matched ventilation and perfusion defects with a normal chest radiograph
  • small subsegmental perfusion defects
Normal scan
  • no perfusion defects
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Article information

rID: 12440
System: Chest
Section: Approach
Synonyms or Alternate Spellings:
  • Modified PIOPED criteria for diagnosis of pulmonary emboli

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