TOACS FCPS Station · Chest X‑ray: Transient Tachypnea of Newborn (TTN)

📷 Chest X‑ray (AP view)

Chest X-ray showing perihilar streaking and fluid in fissures in TTN

Figure 1 · AP chest radiograph · Transient Tachypnea of Newborn (TTN)

🔍 Key radiographic features:

✓ Prominent perihilar vascular markings (pulmonary plethora)
✓ Fluid in interlobar fissures – especially right horizontal fissure
✓ Mild cardiomegaly (enlarged cardiac silhouette)
✓ Small pleural effusions (bilateral, small)
✓ Clear lung fields – no ground-glass opacities (differentiates from RDS)

📋 Clinical scenario (examiner prompt)

A 39‑week term infant is born by elective Caesarean section without labor. Within 2 hours of birth, the infant develops tachypnoea (respiratory rate 80 breaths/min), mild subcostal retractions, and mild expiratory grunting. The infant is pink in room air with SpO2 92%. On auscultation, breath sounds are clear with no crackles. The chest X‑ray (AP view) is shown.

Elective C‑section Perihilar streaking Fluid in fissures Term infant

🧑‍⚕️ Examiner tasks · TOACS

1. Identify the diagnosis from the X‑ray and clinical context.

2. Describe the X‑ray findings (perihilar streaking, fluid in fissures).

3. Explain the pathophysiology (delayed fetal lung fluid clearance).

4. Discuss management and differential diagnosis (supportive care, exclude sepsis/RDS).

⚠️ Key concept: Transient tachypnea of the newborn (TTN) is the most common cause of tachypnea in term infants. It results from delayed clearance of fetal lung fluid, especially after elective C‑section without labor. The condition is self‑limited (resolves in 24‑72 hours) and requires supportive care.

🎯 Expected answers (for examiners)

• Diagnosis: Transient tachypnea of the newborn (TTN)
• X‑ray findings: Prominent perihilar markings, fluid in interlobar fissures (right horizontal), mild cardiomegaly, small pleural effusions
• Pathophysiology: Lack of labor → absent thoracic squeeze and catecholamine surge → delayed ENaC-mediated lung fluid clearance
• Management: Supportive care (oxygen if needed, CPAP for moderate distress), NPO with IV fluids if tachypnoeic, exclude sepsis

⚡ Quick FCPS‑style MCQ

The characteristic chest X‑ray finding in TTN is:

A. Ground‑glass opacities with air bronchograms B. Perihilar streaking and fluid in interlobar fissures C. Hyperinflation with flat diaphragms D. Patchy infiltrates with pleural effusion

📌 Topic summary ·

Definition
Delayed fetal lung fluid clearance

Risk factors
Elective C‑section, late preterm, maternal diabetes

X‑ray findings
Perihilar streaking, fluid in fissures

Duration
24‑72 hours (self‑limited)

Treatment
Supportive care, O₂, CPAP if needed

Differential
RDS, sepsis, MAS, PPHN

Feature	TTN	RDS
Gestational age	Term / late preterm	Preterm
Risk factor	Elective C‑section	Surfactant deficiency
CXR	Perihilar streaking, fluid in fissures	Ground‑glass, air bronchograms
Onset	First 2‑4 hours	Immediately or first hours
Duration	24‑72 hours	Days to weeks

🩻 TOACS FCPS Station · Chest X‑ray: Transient Tachypnea of Newborn (TTN)

📷 Chest X‑ray (AP view)

🧑‍⚕️ Examiner tasks · TOACS

📌 Topic summary ·