ABCDE Approach to Chest X-ray: Complete Guide

If you are familiar with the basics of X-ray, the next step involves the interpretation of the Chest X-Ray. For this, an ABCDE approach to Chest X-Ray is widely used. This mnemonic is widely used worldwide by medical students as a checklist for evaluating the CXR.

In this post, we will provide you with a step-by-step approach to the ABCDE acronym and explain the same with images so that you grab the concepts from scratch.

Overview: ABCDE Approach to Chest X-Ray

When examining a chest radiograph, it is critical to take a methodical approach. The following ABC technique is simple to remember, so when it comes to tests and you are asked to discuss a chest X-ray, you can keep to these fundamentals even if you have no idea what is going on!

  • A: Airway
    • examine the trachea, mainstem bronchi on the right and left, and intermediate bronchi.
  • B: Breathing
    • Examine the lungs to check if they are evenly inflated and compare the lung fields.
    • Examine the borders of each lung.
    • Examine the four silhouettes.
  • C: Circulation
    • Examine the cardiac size.
    • Take a look at the great vessels (pulmonary vessels and aorta).
    • Examine the mediastinum and hilum.
  • D: Disability
    • Look for a fracture, particularly one of the ribs or the shoulder girdle.
  • E: Everything else
    • Check for air under the diaphragm.
    • Check for the edges for surgical emphysema.
    • Check for breast shadows.
    • Check for any foreign bodies and other ‘unnatural presences’.

Need this guide in PDF Format to go through it again?

A: Airway

What to Look for (Airway)?

  1. Tracheal Deviation
  2. Angle of Carina

How to Look for Airway?

  1. At the Top: Begin at the top and work your way down, following the trachea (1). It should be in the midline. It splits at the carina (2), branching into the left mainstem bronchus (3) and the right mainstem bronchus (4).
  2. On the Left: The airway terminates on the left at the bifurcation of the left mainstem bronchus, where it divides into the upper lobe bronchus (5) and lower lobe bronchus (6).
  3. On the Right: The right mainstem bronchus gives off the upper lobe bronchus (7) and continues inferiorly as the intermediate bronchus (8) on the right. The airway terminates at the bifurcation of the intermediate bronchus, where it divides into the middle lobe (9) and lower lobe (10) bronchus.

Interpretation of Normal Airway

The trachea is central.

B: Breathing

Chest X-rays do not reveal many particular illnesses (e.g., pneumonia, bronchial cancer, etc.), but rather pathological indicators that might provide insight into the underlying disease process. The followings are some diseases and symptoms to be aware of while ABCDE approach to Chest X-ray:

What to Look for (Breathing)

  • Consolidation/Airspace shadowing
  • Air bronchogram
  • Collapse (atelectasis)
    • right upper lobe collapse
    • middle lobe collapse
    • right lower lobe collapse
    • left upper lobe collapse
    • left lower lobe collapse
    • complete lung collapse
  • Pneumonectomy
  • Solitary mass lesion
  • Multiple mass lesions
  • Cavitating lung lesion
  • Fibrosis
  • Pneumothorax
  • Tension pneumothorax
  • Hydropneumothorax
  • Pleural effusion
  • Pulmonary edema
  • “Bat’s wing’ pattern shadowing
  • Septal lines

How to Look for Breathing?

It is basic knowledge that Black = Air and White = No Air. There are a total of 5 steps that you must follow for the ABCDE approach to Chest X-Ray:

  1. Are the lungs evenly expanded?
  2. Examine the lung fields for white areas (shadows):
    • Contrast the left and right apexes.
    • Contrast the left upper zone with the right upper zone.
    • Contrast the left and right mid zones.
    • Contrast the lower left zone with the lower right zone.
  3. Examine the borders of each lung.
  4. Examine the costophrenic angles.
  5. Examine the four silhouettes
    • Right Heart Border: The absence of the right heart border denotes a lack of air in the middle lobe (due to collapse or consolidation).
    • Left Heart Border: Lack of the left heart border suggests a loss of air in the lingula (the equivalent of the left lung’s middle lobe).
    • Right and Left Hemidiaphragm: The absence of a distinct diaphragmatic silhouette implies a loss of air in the lower lobe (collapse or consolidation) or the presence of anything between the diaphragm and the lower lobe of the lung (e.g. fluid).

Interpretation of Normal Breathing

The lungs are uniformly expanded and the lung fields are clear.

C: Circulation

What to Look for (Circulation)

  • Dextrocardia
  • Cardiomegaly (enlarged heart)
  • Left atrial enlargement
  • Widened mediastinum
  • Hilar enlargement
  • Hiatus hernia

How to Look for Circulation?

  1. Examine the cardiac size. The width of the heart should not be greater than half the total width of the thorax.
  2. Take a look at the great vessels (pulmonary vessels and aorta).
  3. Because the Latin word for heart is ‘cor’ (as in cor pulmonale), remember to look at the ‘core‘ of the X-ray.
    • Check the mediastinum, both hilum, and for a hiatus hernia.

Interpretation of Normal Circulation

The heart size is normal. There is no shift of the mediastinum. The mediastinal contours and hilum appear normal.

D: Disability

What to Look for (Disability)

  • Fractures of the ribs and other bony anomalies

How to Look for Disability?

  1. Examine the ribs for any fractures (#) or bony abnormalities. Remember to rotate the Xray 90 degrees.
  2. Bring your gaze closer to the CXR and examine the borders of each individual bone for fractures. Examine each bone for regions of blackness and compare the density of the bones on both sides. They ought to be the same.
  3. Repeat the examination, searching for any fractures or bone abnormalities in the vertebrae, clavicles, or shoulder girdle.
Why Rotation of CXR?

This is due to the fact that when you look at an xray, your eyes are accustomed to look at the structure of the lungs and heart, among other things. Rotating the picture, on the other hand, confuses your brain, and your eyes focus on the more dense sections (ribs and other bones), making it easier to identify a fracture or skeletal irregularity.

Interpretation of No Disability

I cannot see a fracture or bony abnormality.

E: Everything Else

What to Look for (Everything Else)

  • Air under the diaphragm (pneumoperitoneum)
  • Subcutaneous emphysema/Surgical emphysema
  • Mastectomy
  • Foreign bodies and medical interventions

How to Look for Everything Else?

  1. Examine the hemidiaphragm for air under the diaphragm. Due to the location of the heart, both hemidiaphragm normally peak in the center, with the right hemidiaphragm being higher than the left (not due to the liver). Areas of calcification beneath the right hemidiaphragm (gallstones) and dilated loops of the bowel under the hemidiaphragm are two more intra-abdominal findings that may be observed.
  2. Examine the margins of the body and the whole film for surgical emphysema.
  3. Look for breast shadows in female patients. A prior mastectomy might be indicated if one breast is smaller or absent (may explain secondary lung metastasis). Look for masses in the axillae and lower neck.
  4. Look for ‘other strange presences‘ and foreign bodies.

Interpretation of Normal “Everything Else”

There is no evidence of air under the diaphragm, surgical emphysema, or any foreign body.

Need more? Read our complete guide on Chest Xrays:

If you have any queries on our “ABCDE approach to Chest X-Ray Interpretation”, please leave feedback or query in the comments below.

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