Last revised by Dr Daniel J Bell on Radiopedia.org on 16 Jun 2021
ABCDEFGHI can be used to guide a systematic interpretation of chest x-rays.
- Assessment of quality / Airway
- Bones and soft tissues
- Cardiac outline/associated structures
- Diaphragm
- Effusions / Extrathoracic soft tissue
- Fields, fissures and foreign bodies
- Great vessels / gastric bubble
- Hila and mediastinum
- Impression
- Related articles
Assessment of quality / Airway
The quality of the image can be assessed using the mnemonic PIER:
- position: is this a supine AP file? PA? Lateral?
- inspiration: count the posterior ribs. You should see 10 to 11 ribs with a good inspiratory effect
- exposure: well-exposed films have good lung detail and an outline of the spinal column
- rotation: the space between the medial clavicle and the margin of the adjacent vertebrae should be roughly equal to each other; look for indwelling lines or objects
Bones and soft tissues
Scan the bones for symmetry, fractures, osteoporosis, and lesions. Evaluate the soft tissues for foreign bodies, swelling, and subcutaneous air.
Cardiac
Evaluate the heart size: the heart should be <50% of the chest diameter on PA films and <60% on AP films. Check for the heart shape, calcifications, and prosthetic valves.
Diaphragm
Check the hemidiaphragms for position (the right is commonly slightly higher than the left due to the liver) and shape (may be flattened bilaterally in chronic asthma or emphysema, or unilaterally in case of tension pneumothorax or foreign body aspiration). Look below the diaphragm for free gas.
Effusions / Extrathoracic soft tissue
Pleural effusions may be large and obvious or small and subtle. Always check the costophrenic angles for sharpness (blunted angles may indicate small effusions). Check the lateral film for small posterior effusions (more sensitive for small effusions).
Fields, fissures and foreign bodies
Check lungs for infiltrates (interstitial vs. alveolar), masses, consolidation (+/- air bronchograms), pneumothoraces, and vascular markings. Vessels should taper and should be almost invisible at the lung periphery.
Evaluate the major and minor fissures for thickening, fluid or change in position.
Check the position of foreign bodies e.g. ETT, NGT, pacemaker leads, central venous lines etc. Comment on previous surgery e.g. cholecystectomy clips, sternotomy wires.
Great vessels / gastric bubble
Check aortic size and shape and the outlines of pulmonary vessels. The aortic knob should be clearly seen. The gastric bubble should be seen clearly and not displaced.
Hila and mediastinum
Evaluate the hila for lymphadenopathy, calcifications, and masses. The left hilum is normally higher than the right. Check for widening of the mediastinum (which may indicate aortic dissection in the appropriate clinical setting) and tracheal deviation (which may indicate a mass effect, e.g. from large goitre, or tension pneumothorax). In children, be careful not to mistake the thymus for a mass!
Impression
In most cases, an impression is worthwhile as it not only forces you to synthesise all the findings together but acts as a double check.
SUMMARY OF THE ABCDEFGHI approach
A – Assessment of quality / Airway
– Position: supine AP ?PA? Lateral?
– Inspiration: count 10-11 posterior ribs
– Exposure: good lung detail and outline of spinal column
– Rotation: medial clavicle to margin of adjacent vertebrae should be roughly equal
B – Bones and soft tissues
– Scan for symmetry, fractures, osteoporosis, and lesions
– Evaluate soft tissues for foreign bodies, swelling, and subcutaneous air
C – Cardiac
– Evaluate heart size: <50% of chest diameter on PA films and <60% on AP films
– Check heart shape, calcifications, and prosthetic valves
D – Diaphragm
– Check hemidiaphragms for position and shape
– Look below diaphragm for free gas
E – Effusions / Extrathoracic soft tissue
– Check for pleural effusions and sharpness of costophrenic angles
– Check lateral film for small posterior effusions
F – Fields, fissures and foreign bodies
– Check lungs for infiltrates, masses, consolidation, pneumothoraces, and vascular markings
– Evaluate major and minor fissures for thickening, fluid, or change in position
– Check position of foreign bodies and comment on previous surgery
G – Great vessels / gastric bubble
– Check aortic size and shape, outlines of pulmonary vessels, and aortic knob
– Check gastric bubble for clarity and displacement
H – Hila and mediastinum
– Evaluate hila for lymphadenopathy, calcifications, and masses
– Check for widening of mediastinum and tracheal deviation
– Be careful not to mistake the thymus for a mass in children
I – Impression
– Synthesize all findings together
– Provide an overall impression as a double check