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Neonatal respiratory distress: RDS, TTN and MAS
Gestational age, mode of delivery and the chest X-ray separate the three main causes: surfactant deficiency in the preterm baby (RDS), retained lung fluid after caesarean section (TTN) and meconium aspiration in the term or post-term baby (MAS).
Why it matters in the exam
Exam questions present a newborn with tachypnoea, grunting, nasal flaring and recessions, and give three clues: gestational age, type of delivery and the X-ray appearance. From these the candidate must choose a diagnosis and treatment: CPAP and surfactant in RDS, supportive care in TTN, and respiratory support with watchfulness for PPHN and pneumothorax in MAS. Prevention is also asked: antenatal steroids before a preterm birth.
Recurring special cases are congenital diaphragmatic hernia (scaphoid abdomen, bowel sounds in the chest, needs immediate intubation rather than bag-mask ventilation) and congenital GBS pneumonia, which looks like RDS. The key change in newborn resuscitation guidance: a non-vigorous baby born through meconium-stained fluid no longer has routine tracheal suctioning; the usual initial steps and ventilation come first.
In a long question, first mark the gestational age and the type of delivery, and only then read the X-ray description. In most cases the first two facts already narrow the diagnosis to one option, and the X-ray only confirms it. When the picture fits none of the three, think of pneumonia, diaphragmatic hernia or heart disease.
Key points
- RDS is the surfactant-deficiency disease of preterm babies: small volumes and ground-glass on the X-ray.
- RDS treatment: early CPAP, and surfactant when FiO2 rises above 0.30.
- TTN: term baby after caesarean without labour, resolves within 24–72 hours.
- MAS: term or after 41 weeks with fetal distress; risk of pneumothorax and PPHN.
- Antenatal steroids between 24 and 34 weeks reduce RDS and mortality.
Summary table
| Condition | Who is at risk | Chest X-ray | Treatment |
|---|---|---|---|
| RDS (surfactant deficiency) | Preterm babies, especially below 32 weeks; maternal diabetes; male sex | Small lung volumes, ground-glass and air bronchograms | CPAP from the delivery room; surfactant if FiO2 above 0.30 on CPAP |
| TTN (transient tachypnoea) | Term or near-term, caesarean without labour | Fluid in the fissures, prominent vessels, mild hyperinflation | Supportive; resolves within 24–72 hours |
| MAS (meconium aspiration) | Term or after 41 weeks, fetal distress | Hyperinflation with patchy opacities; sometimes pneumothorax | Oxygen and ventilation as needed; watch for PPHN; surfactant in severe cases |
| Congenital pneumonia | Prolonged rupture of membranes, maternal fever, GBS | Opacities; may mimic RDS | Cultures and ampicillin + gentamicin |
| Congenital diaphragmatic hernia | Usually left-sided | Bowel loops in the chest, mediastinal shift | Immediate intubation and gastric tube; no bag-mask ventilation |
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Sources
- European Consensus Guidelines on the Management of Respiratory Distress Syndrome, 2022 update — Delivery-room stabilisation, CPAP and surfactant
- AHA and AAP Neonatal Resuscitation Guidelines, 2020 — Meconium-stained amniotic fluid and initial steps
- Nelson Textbook of Pediatrics, 22nd edition (2024) — Respiratory Tract Disorders of the Newborn
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.