Acute Epiglottitis
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Direct answer
Acute epiglottitis is a rapidly progressive infection of the epiglottis that can obstruct the airway within hours. Haemophilus influenzae type b was the classic cause, and conjugate Hib vaccination has made it much rarer. The child sits upright and drools, and since the airway can close suddenly, management belongs in a controlled setting with no throat examination.
What you must remember
- Causative organism: Haemophilus influenzae type b historically; Streptococcus pneumoniae and Staphylococcus aureus can also cause it.
- Onset: rapid, over hours rather than days, with high fever, severe sore throat and dysphagia.
- Voice and cough: a muffled, hot-potato voice and stridor, with no barking cough as the key feature.
- Posture: the tripod position, sitting upright and leaning forward, mouth open, drooling and refusal to lie flat.
- Thumb sign: a swollen epiglottis seen on a lateral neck radiograph, obtained only if the child is stable.
- Airway management: secure the airway in theatre with an anaesthetist and surgeon present, and avoid any manoeuvre that provokes spasm.
- Treatment: a third-generation cephalosporin such as ceftriaxone; corticosteroids are used by many centres, though evidence is limited, and household contacts receive rifampicin prophylaxis when Hib is confirmed.
Epiglottitis versus croup at the bedside
A 3-year-old with fever and a muffled voice can look like croup on the surface, so the features need separating quickly. The table gives the discriminating points.
| Feature | Acute epiglottitis | Croup |
|---|---|---|
| Onset | Over hours | Over one to three days |
| Cough | Absent or muffled | Classic barking cough |
| Voice | Muffled, hot-potato | Hoarse |
| Posture and drooling | Tripod, sits upright, drools | Settles comfortably, no drooling |
| General state | Toxic, high fever | Usually well between episodes |
| Lateral neck radiograph | Thumb sign | Not the diagnostic finding |
| AP neck radiograph | Normal or non-specific | Steeple sign |
| Common cause | Haemophilus influenzae type b (historically) | Parainfluenza viruses |
The clinical picture, not the X-ray, separates these conditions in an emergency. Any child with epiglottitis features is managed as an airway emergency.
Drooling and a tripod posture push the picture firmly away from croup. Radiology is secondary, so the decision to stabilise the airway does not wait for a film, and any distressed child needs anaesthetic and senior input at once.
Where the exam tries to catch you
Four traps recur on this question type.
- Trap: inspecting the throat with a tongue depressor to confirm the diagnosis Correct: this can precipitate complete obstruction, so diagnosis rests on the clinical picture and controlled airway assessment.
- Trap: using the steeple sign to diagnose epiglottitis Correct: the steeple sign belongs to croup, whereas the thumb sign on a lateral film points to epiglottitis.
- Trap: sending an unstable child to radiology before securing the airway Correct: imaging waits until the airway is secured, because the child may deteriorate on the table.
- Trap: treating epiglottitis like simple croup with nebulised adrenaline alone Correct: epiglottitis needs antibiotics and definitive airway planning, not only symptomatic treatment.
Frequently asked questions
What is the thumb sign in acute epiglottitis?
The thumb sign in acute epiglottitis is a swollen, thickened epiglottis seen as a rounded shadow on a lateral neck radiograph. It distinguishes epiglottitis from croup, which shows a steeple sign on the anteroposterior film instead.
How does acute epiglottitis differ from croup?
Acute epiglottitis differs from croup by its rapid onset over hours, absent barking cough, muffled voice, drooling and toxic appearance. Croup develops over one to three days, produces a barking cough and hoarseness, and is usually managed with steroids and nebulised adrenaline.
Why must the airway be secured before imaging in acute epiglottitis?
The airway must be secured before imaging in acute epiglottitis because complete obstruction can occur without warning. Imaging or throat examination can provoke spasm and collapse, so these are done only when the child is stable or in a controlled setting.
Which antibiotic is used for acute epiglottitis?
Ceftriaxone is a commonly used third-generation cephalosporin for acute epiglottitis, with cefotaxime an alternative in many protocols. Antibiotic choice is then adjusted to culture results and local policy, while the airway remains the first priority.
Do household contacts of acute epiglottitis need prophylaxis?
Household contacts of a child with confirmed Haemophilus influenzae type b epiglottitis should receive rifampicin prophylaxis under local protocol. Eligibility depends on the contact's age, vaccination status and the household setting.