Chest radiograph assessment using ABCDEFGHI

Last revised by Daniel J Bell on 16 Jun 2021

ABCDEFGHI can be used to guide a systematic interpretation of chest x-rays.

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

Scan the bones for symmetry, fractures, osteoporosis, and lesions. Evaluate the soft tissues for foreign bodies, swelling, and subcutaneous air.

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.

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.

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).

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.

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.

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 goiter, or tension pneumothorax). In children, be careful not to mistake the thymus for a mass!

In most cases, an impression is worthwhile as it not only forces you to synthesize all the findings together but acts as a double check.

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