The neonatal chest X-ray

Written by the X-Ray Atlas editorial team from the sources listed below · Medical review pending · Updated 24 October 2026 · Level: Advanced

The neonatal chest X-ray (CXR) is taken in difficult conditions: a tiny, often ventilated baby, lying supine in an incubator, with lines and tubes crossing the film. It is also one of the most consequential films in medicine, because it guides ventilation, surfactant and urgent surgery. The trick is to combine the film with three facts: gestational age, age in hours, and the mode of delivery. With those, and an assessment of lung volume, the common diagnoses usually separate. This page covers technique, normal appearances, the main causes of neonatal respiratory distress, and the lines and tubes you will be asked about.

1. Technique and normal appearances

• Films are AP and supine. Air rises to the front of the chest and fluid lies at the back, which changes how pneumothoraces and effusions look.
• Rotation is common and changes the apparent size of the heart and the density of each lung. Compare the lengths of the anterior ribs on both sides and the position of the clavicles.
• Inspiration varies with ventilation and the moment of exposure. Over-inflation on a ventilated baby may mean excessive pressure; under-inflation may mean poor recruitment or surfactant deficiency.
• Keep exposures and repeats to a minimum (see radiation protection). Collimate tightly, but include the abdomen when lines need checking.

Normal findings that cause confusion

• The thymus is large in infants. It widens the upper mediastinum and can form a triangular "sail" projecting to one side (usually the right), or a gently undulating edge where the ribs indent it (the thymic wave sign). It should not be mistaken for consolidation or a mass. It can shrink quickly with stress or illness.
• The cardiothoracic ratio can be up to about 0.6 in infants, and the thymus can make it hard to measure.
• Skin folds from the baby or the incubator mattress can mimic a pneumothorax; follow the line beyond the chest wall.

2. Start with lung volume

Lung volume	Typical causes
Low	Respiratory distress syndrome; under-ventilation; pulmonary hypoplasia; poor inspiration at exposure.
Normal or high	Transient tachypnoea of the newborn; meconium aspiration; pneumonia (variable); air trapping; over-ventilation.

Then ask: is the opacification diffuse and uniform (RDS), streaky and perihilar (TTN) or coarse and patchy (meconium aspiration, pneumonia)? Are there effusions? Is there air in the wrong place?

3. Respiratory distress syndrome (RDS)

RDS (surfactant deficiency, formerly hyaline membrane disease) occurs mainly in premature infants, whose lungs do not yet make enough surfactant. The alveoli collapse, so the lungs become small and airless.

• Low lung volumes.
• Diffuse, bilateral, symmetrical fine granular ("ground glass") opacification.
• Air bronchograms extending to the periphery.
• In severe cases a complete white-out, with loss of the heart and diaphragm outlines.

Surfactant treatment can produce a rapid but sometimes asymmetric improvement, which should not be mistaken for new consolidation. Complications include pneumothorax, pulmonary interstitial emphysema and, in the longer term, bronchopulmonary dysplasia (BPD), a chronic lung disease seen as coarse reticular lines with cystic change and areas of over-inflation.

4. TTN, meconium aspiration and pneumonia

Condition	Typical baby	X-ray
Transient tachypnoea of the newborn (TTN)	Term, often after Caesarean section; slow clearance of lung fluid.	Normal or increased volumes, prominent perihilar streaky opacities, fluid in the fissures and small effusions. It clears within about 24–72 hours.
Meconium aspiration syndrome	Term or post-term, meconium-stained liquor.	Hyperinflation with coarse, patchy, asymmetric opacities from a mix of collapse and air trapping. A high risk of pneumothorax.
Neonatal pneumonia (for example group B streptococcus)	Any gestation; maternal risk factors or sepsis.	Variable. It can look just like RDS. Pleural effusions favour pneumonia over RDS.

5. Air leaks: pneumothorax and PIE

• Pneumothorax is common in ventilated babies and in meconium aspiration. Because the baby is supine, air collects anteriorly and medially. Instead of a visible pleural edge you may see a hyperlucent hemithorax, an unusually sharp heart border or diaphragm, or a deep, lucent costophrenic angle. A tension pneumothorax shifts the mediastinum away and flattens or inverts the diaphragm. Bedside transillumination can help, but a deteriorating baby should not wait for a film. See pneumothorax.
• Pneumomediastinum can lift the thymus off the heart, producing a "spinnaker sail" or "angel wing" appearance. See pneumomediastinum.
• Pulmonary interstitial emphysema (PIE) occurs in ventilated preterm babies: air escapes into the lung interstitium, giving linear and small cystic lucencies radiating from the hila, sometimes in one lobe. It suggests barotrauma and often precedes a pneumothorax.

6. Diaphragmatic hernia and heart shapes

Congenital diaphragmatic hernia (CDH)

CDH is usually left-sided and posterolateral (Bochdalek type). Bowel herniates into the chest during development, and the lung on that side (and often both lungs) is hypoplastic.

• Gas-filled bowel loops in the left hemithorax; in the first hours, before bowel fills with gas, the chest may look like an opaque mass.
• Mediastinal shift to the right.
• Few or no gas-filled bowel loops in the abdomen.
• The tip of an NG tube may be seen curling up into the chest if the stomach has herniated.

The differential includes congenital pulmonary airway malformation (CPAM), which also produces cystic lucencies in the chest; abdominal gas pattern and an NG tube help distinguish them.

Congenital heart disease patterns

Plain films are not diagnostic of heart disease, which is assessed by echocardiography, but some shapes are classic exam material:

• Boot-shaped heart (coeur en sabot) with reduced pulmonary vascularity: tetralogy of Fallot.
• Egg on a string (narrow upper mediastinum): transposition of the great arteries.
• Snowman or figure of eight: supracardiac total anomalous pulmonary venous return.

7. Lines and tubes

Tube and line confirmation must follow your organisation's policy. That policy usually sets who may confirm a position, which documentation is needed, and when a radiologist must review the film. This page explains the radiographic criteria. It does not authorise anyone to confirm positions.

Device	Usual target (approximate; sources vary)	Watch for
Endotracheal tube	Tip at about T1–T2, or roughly 1–2 cm above the carina. Head position moves the tip: flexion moves it down, extension up.	Right main bronchus intubation: collapse of the left lung or right upper lobe and over-inflation on the right. See ETT position.
Umbilical venous catheter (UVC)	Runs upward and slightly right through the ductus venosus; tip at the IVC–right atrial junction, roughly T8–T9, just above the diaphragm.	Tip in the liver or portal vein (stays below the diaphragm), or across into the left atrium.
Umbilical arterial catheter (UAC)	Runs down into an iliac artery, then up the aorta, to the left of the spine. High position T6–T10, or low position L3–L5.	Avoid about T11–L2 (coeliac, superior mesenteric and renal arteries); some sources quote T10–L2.
Nasogastric / orogastric tube	Tip in the stomach, below the left hemidiaphragm.	Coiling in the oesophagus (for example in oesophageal atresia), or tube in the airway. See NG tube position.

Ultrasound is increasingly used to confirm umbilical line positions. See also central lines and PICCs.

Red flags: act now

What to focus on, by role

Role	Priorities
Medical student	The normal thymus, the RDS versus TTN contrast, and the appearance of CDH.
Neonatal nurse	Recognise a sudden deterioration that may be a pneumothorax or tube displacement, and know local policy on who confirms line and tube positions.
Junior doctor	Combine gestation, age in hours and lung volume; review every line and tube on every film; act on air leaks.
Radiographer	Minimise rotation and repeats in the incubator, collimate correctly, and include the abdomen when umbilical lines are present.
Advanced / FRCR	PIE, BPD, CPAM versus CDH, cardiac silhouettes and subtle supine air leaks.

Practise on paediatric X-rays →

References

1. Radiopaedia. Umbilical arterial catheter. radiopaedia.org
2. Radiopaedia. Endotracheal tube position. radiopaedia.org
3. Radiology Masterclass. Chest X-ray anatomy. radiologymasterclass.co.uk
4. Royal College of Radiologists. Reducing the harm caused by misplaced nasogastric feeding tubes in adults, children and infants (audit). rcr.ac.uk
5. Royal College of Radiologists. iRefer: making the best use of clinical radiology. irefer.org.uk

For education only. Not a substitute for a formal report, senior review or your local policy. Never use this page to make decisions about a real patient.