Last reviewed 01/2018

Diagnosis is based upon clinical and biochemical features. A commonly used set of diagnostic criteria are those published by Gurd. Gurd produced lists of major and minor criteria. For the diagnosis of FES to be made at least one major and four minor criteria must be present.

Major criteria include:

  • axillary or subconjunctival petechiae
  • hypoxemia (PaO2 < 60 mmHg; FiO2 = 0.4)
  • central nervous system depression disproportionate to hypoxemia
  • pulmonary oedema

Minor criteria include:

  • tachycardia greater than 110 bpm
  • pyrexia greater than 38.5 degrees C
  • emboli present in the retina on fundoscopy
  • fat present in urine
  • a sudden inexplicable drop in haematocrit or platelet values
  • increasing ESR
  • fat globules present in the sputum

Gurd's criteria have been questioned however, and Murray and Racz suggested that tachycardia, tachypnoea, pyrexia and CNS involvement in the presence of arterial hypoxemia (PaO2 < 7.0 KPa) were better indicators. More recently, a fat embolism index has been proposed as a semiquantitative means of diagnosing FES in which each of seven clinical features is given a particular score. A score of more than 5 is required for a positive diagnosis.