Clinical exam · Respiratory system
Atelectasis syndrome !
- Syndrome
Part of the lung collapses and loses air: that side of the chest pulls in and the trachea shifts toward it.
Updated 2026-11-01
See it in 3D: Lobar bronchi · Main bronchi · Trachea · Diaphragm
What it is
Atelectasis is collapse of a segment, a lobe or a whole lung with loss of volume. The classic exam form is obstructive: a blocked bronchus stops air entry, the distal air is absorbed and the lung collapses, pulling nearby structures toward the affected side. It is very common after surgery, especially upper abdominal and chest surgery.
Key findings
- Small plate-like atelectases give no exam findings.
- The radiograph shows an opacity with signs of volume loss (fissure shift, high diaphragm, mediastinum toward the side).
Pathophysiology
- Obstructive (resorptive): a blocked bronchus traps distal air, the blood absorbs it and the alveoli collapse.
- Non-obstructive: from compression (effusion, pneumothorax, mass), lack of surfactant (respiratory distress syndrome) or scarring (tuberculosis, fibrosis).
- Volume loss pulls the mediastinum, trachea and diaphragm toward the collapsed side.
- Collapsed lung stays perfused but not ventilated: shunt and hypoxaemia.
| Inspection | Palpation (fremitus) | Percussion | Auscultation |
|---|---|---|---|
| Obstructive: retraction, expansion ↓; trachea toward the affected side | Reduced or absent fremitus | Dullness | Breath and voice sounds absent |
| Non-obstructive (open bronchus): mild retraction; trachea toward the affected side | Normal or increased fremitus | Dullness | Bronchial breathing and crackles may be heard |
Common causes
- Postoperative (the most common cause in hospital).
- Mucus plugging in patients with heavy secretions or on mechanical ventilation.
- Endobronchial tumour (lung cancer) in adults.
- Inhaled foreign body in children.
- Compression by effusion or pneumothorax; surfactant deficiency in the preterm newborn.
Tests that confirm it
- Chest radiograph with signs of volume loss.
- Chest CT to look for the cause of obstruction.
- Bronchoscopy when tumour, foreign body or a persistent plug is suspected.
Test yourself
Think of the answer, then tap the question to see it.
Which way does the trachea shift in a lobar atelectasis?
Toward the side of the atelectasis, because volume loss pulls the mediastinum.
What exam does obstructive atelectasis give?
Retraction and reduced expansion on that side, reduced or absent fremitus, dullness and absent breath sounds.
What is the mechanism of resorptive atelectasis?
A blocked bronchus stops air entry; the trapped air is absorbed into the blood and the distal alveoli collapse.
Which cause of obstructive atelectasis is typical in young children?
An inhaled foreign body.
See it in 3D
The structures of Durgical's 3D anatomy where it is found.
Related
- The pleuropulmonary syndromes: the comparison table to know
- Consolidation syndrome
- Pleural effusion syndrome
- Chest palpation: expansion and tactile fremitus
Related conditions
- Atelectasis
- Lung cancer
- Neonatal respiratory distress syndrome (hyaline membrane disease)
- Pleural effusion
Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.
Sources: Atelectasis: MedlinePlus Medical Encyclopedia (MedlinePlus, U.S. National Library of Medicine, 2024); Breath sounds: MedlinePlus Medical Encyclopedia (MedlinePlus, U.S. National Library of Medicine, 2024).
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Representative model, for educational purposes only.