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Fat embolism syndrome
Fat embolism syndrome usually appears 24–72 hours after a long bone or pelvic fracture, with a triad of breathing difficulty and hypoxaemia, confusion and a petechial rash; treatment is supportive, and the key prevention is early fixation of femoral fractures.
Why it matters in the exam
The typical stem describes a young patient with a femoral fracture after a road accident who is stable on the first day and within a day or two develops breathlessness, falling oxygen saturation, confusion or agitation and a rash of small bleeding spots in the armpits, conjunctiva and mouth. The rash is a relatively specific sign, but it appears in only some patients and sometimes late. The mechanism involves fat droplets from the marrow entering the blood and an inflammatory reaction in the lungs and vessels. Diagnosis is clinical, helped by the Gurd criteria and by excluding other diagnoses: pulmonary embolism from thrombosis, aspiration pneumonia, lung contusion, intracranial bleeding and brain injury. A chest radiograph may show diffuse infiltrates, and brain MRI sometimes shows scattered tiny lesions. Risk factors: multiple long bone fractures, young age, closed fracture and delayed fixation. Early fixation of a femoral fracture, within 24 hours when the patient's condition allows, reduces the risk of the syndrome and of lung complications. Treatment is supportive only: oxygen, ventilation when needed, adequate blood volume and neurological monitoring; steroids are not routine treatment. Most patients recover fully, but in severe cases the syndrome is life-threatening. In a patient with many injuries and an unstable condition, temporary external fixation (damage control) is preferred over a long immediate operation. In differential diagnosis questions, onset immediately after injury fits lung contusion or bleeding better than this syndrome.
Key points
- 24–72 hours after a long bone or pelvic fracture.
- Triad: hypoxaemia, confusion and petechial rash.
- Clinical diagnosis after excluding pulmonary embolism and brain bleeding.
- Supportive care: oxygen and ventilation as needed.
- Prevention: early fixation of a femoral fracture.
Summary table
| Component | Finding | Note |
|---|---|---|
| Respiratory | Breathlessness, hypoxaemia, infiltrates on chest radiograph | The most common sign; may progress to respiratory failure |
| Neurological | Confusion, agitation, reduced consciousness | No typical focal finding; MRI shows tiny lesions |
| Skin | Petechial rash in the armpits, conjunctiva and mouth | Specific sign, present in only some patients |
| Timing | 24–72 hours after injury | Distinguishes it from conditions that appear at once |
| Prevention and treatment | Early femoral fixation; supportive care | Steroids are not routine treatment |
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Sources
- Rockwood and Green's Fractures in Adults, 9th ed. (2019) — Systemic Complications after Trauma
- Gurd AR, Wilson RI, J Bone Joint Surg Br (1974) — The fat embolism syndrome
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.