Steeple Sign, Thumb Sign & Tripod Sign Explained | Croup vs Epiglottitis

Steeple Sign, Thumb Sign & Tripod Sign

Croup and Acute Epiglottitis are two important pediatric airway emergencies. Students often confuse the signs seen in these two conditions.

In this post, we will discuss:

• Steeple Sign
• Thumb Sign
• Tripod Sign

Steeple Sign

📌 Type of Sign

👉 Radiological sign

Seen on X-ray Neck AP View

🔍 What is the Sign?

Steeple sign refers to Narrowing of the subglottic airway seen on an AP radiograph of the neck. This produces a characteristic tapered appearance of the upper airway.

🦠 Seen In

Croup (Acute Laryngotracheobronchitis)

🧠 Why does it occur?

In croup there is:

• Inflammation
• Subglottic edema

The subglottic region becomes narrowed.

Since the subglottis is already the narrowest part of the pediatric airway, even a small amount of edema produces marked airway narrowing.

On the AP neck radiograph, the upper tracheal air column appears progressively narrowed and tapered.

⛪ Why is it called Steeple Sign?

The tapering air column resembles the pointed top of a Church steeple

Hence the name, Steeple Sign.

What is the most common causative organism of croup?

What is the narrowest part of the pediatric airway?

What is the typical presentation of croup?

Thumb Sign

📌 Type of Sign

👉 Radiological sign

Seen on X-ray Neck Lateral View.

🔍 What is the Sign?

Thumb sign refers to Enlarged swollen epiglottis appearing as a Thumb shaped soft tissue shadow on a lateral neck radiograph.

🦠 Seen In

Acute Epiglottitis

🧠 Why does it occur?

Acute epiglottitis causes:

• Severe inflammation
• Marked edema of epiglottis
• Edema of aryepiglottic folds

The swollen epiglottis loses its normal thin leaf like appearance and becomes thick and rounded.

👍 Why is it called Thumb Sign?

The swollen epiglottis resembles a human thumb.

Hence the name: Thumb Sign

WHat is the most common organism causing acute epiglottitis?

What is the most dangerous complication of acute epiglottitis?

Should aggressive throat examination be performed in acute epiglottitis?

Tripod Sign

📌 Type of Sign

👉 Clinical sign

Observed during General physical examination.

🔍 What is the Sign?

The child sits in a characteristic posture:

• Leaning forward
• Neck hyperextended
• Chin thrust forward
• Mouth open
• Tongue protruding
• Hands placed on knees or bed for support

This posture is known as the Tripod Position.

🦠 Seen In

Acute Epiglottitis

🧠 Why does it occur?

In acute epiglottitis:

• Epiglottis becomes swollen
• Supraglottic airway becomes critically narrowed

The child instinctively assumes the tripod position to maximize airflow.

This posture:

• Pulls the epiglottis anteriorly
• Widens the supraglottic airway
• Improves ventilation

🪑 Why is it called Tripod Sign?

The posture resembles a Three legged tripod.

Hence the name: Tripod Sign

What is the classical triad of acute epiglottitis?

What condition does hyperextended neck with drooling suggests?

What condition does barking cough with inspiratory stridor but no drooling suggests?

⭐ Rapid Revision Table

🧠 Viva Pearls

• Steeple sign is seen in croup.
• Thumb sign and tripod sign are seen in acute epiglottitis.
• Steeple sign is seen on AP neck X-ray.
• Thumb sign is seen on lateral neck X-ray.
• Subglottis is the narrowest part of the pediatric airway.
• Drooling strongly favors epiglottitis over croup.
• Aggressive throat examination should be avoided in epiglottitis.
• Tripod posture helps relieve supraglottic airway obstruction.