Transient tachypnoea of the newborn — viva

Opening (2 minutes)

The candidate should recognise early neonatal respiratory distress in a term infant delivered by elective caesarean without labour and generate transient tachypnoea of the newborn as the leading diagnosis while committing to exclude alternatives. [3]

Branch 1 — pathophysiology

Examiner: "Why does this baby have respiratory distress when a baby born vaginally after labour does not?" The expected answer is the labour catecholamine surge upregulating epithelial sodium channels (ENaC) that absorb fetal lung fluid, with vaginal delivery providing additional mechanical clearance. [2]

Elective caesarean without labour removes the catecholamine signal and the thoracic squeeze, delaying ENaC activation and leaving residual alveolar fluid that lowers compliance. A strong candidate links this directly to the preventable nature of early elective delivery. [2]

Branch 2 — investigations

Examiner: "What does the chest radiograph show, and what would change your mind about the diagnosis?" The expected findings are perihilar streaking, hyperinflation and fluid in the minor fissure; a ground-glass, low-volume pattern would redirect toward RDS, and focal consolidation toward pneumonia. [1]

The candidate should mention a pre-post-ductal saturation comparison to screen for shunting, blood culture with inflammatory markers for sepsis, and the highly specific lung ultrasound double lung point where available. [1]

Branch 3 — escalation

Examiner: "Two hours later the SpO₂ is 90% in 35% oxygen. What now?" The correct move is to add bubble CPAP at around 5–6 cmH₂O and re-evaluate, recognising that an oxygen requirement climbing above 40% is a red flag that this may not be simple TTN. [3]

The candidate should articulate when to step back and reconsider surfactant deficiency, sepsis, congenital heart disease or persistent pulmonary hypertension, rather than tightening the TTN label. [1]

Closing (1 minute)

Summarise the plan: supportive care with oxygen to SpO₂ 91–95%, hold feeds while tachypnoeic, empirical antibiotics until sepsis excluded, CPAP for moderate distress, and clear thresholds for re-evaluation and discharge. [3]