The ABCDEFGHI’s of Chest X-Ray Interpretation

Do you really know how to read a chest X-ray? It’s important that as nurse practitioners and physician assistants we can scrutinize the quality of chest X-rays an have the skills to interpret this important diagnostic tool. With so many crucial body systems encompassed in one test it’s necessary to have a systematic method for approaching chest X-ray interpretation. Fortunately, simply following the first few letters of the alphabet can help.

The first thing you should do when interpreting a chest X-ray is to check the patient name on the image. Are you interpreting the right X-ray for the right patient? Second, assess X-ray quality.  Does the picture include the complete anatomy of the chest? For example, make sure the apices of the lungs are not cut off and are included in the picture. You can’t accurately diagnose a pulmonary condition if you can’t see the entire lung. Make sure the picture isn’t over or under penetrated and that the angle from which the picture was taken is appropriate. If you aren’t sure how to critically assess the quality of an X-ray, there are plenty of online tutorials that can help.

Once you’ve analyzed the quality of your picture, you’re ready to start reading. Here’s what to look for:

Airway

Look at the trachea and its branches to make sure the airway is patent and midline. Narrowing of the airways can indicate edema or stenosis. In a tension pneumothorax, the airway will be deviated away from the affected side. Note that in kids, the airway should be straight. In adults, it can be deviated to the right due to the aortic arch.

Bones and Breast Shadows

Check the bones including the clavicles, ribs, scapulae, thoracic vertebrae and humeri looking at size, shape, shadows and boarders. Remember, don’t miss the bony structures outside the chest as these are often visible in the X-ray. Examen the bony structures for fractures, lytic lesions (darker areas or changes in bone density), and deformities. At the joints, look at joint spaces for narrowing, widening, and air in the joint space.

Cardiac Silhouette and Costophrenic Angles

The cardiac silhouette is the white space on the X-ray representing the heart. Normal heart size is half of the chest width. Most computerized X-ray viewing program have an easy to use measuring tool that can quickly help you determine if the heart is enlarged, known as cardiomegaly. Examen the shape of the heart. A water-bottle-shaped heart can be indicative of pericardial effusion. Note the location of the heart, which side is it on? The boarders around the heart should be clear. An undefined right boarder suggests middle lobe lung consolidation and a poorly defined left boarder suggests lingular lung consolidation.

Check the costophrenic angles, where the diaphragm and chest wall meet. The angle should be well defined. Whiteness or poorly defined angles can be a sign of pleural effusion or consolidation.

Diaphragm

The outline of the diaphragm should be smooth and the right ride of the diaphragm higher than the left. The highest point of the left diaphragm should be just lateral to the middle of the lung and the highest point on the right in the middle of the right lung. Deviation to one side or the other can signal pneumothorax. Look for air below the diaphragm which may indicate bowel perforation.

Extrathoracic Tissues

Examen the soft tissues for abnormalities, specifically lymph nodes and subcutaneous emphysema (air below the skin), as well as any other lesions.

Fields

Dividing the lungs into sections, upper, middle, and lower, and begin to examen the lungs themselves. Look for symmetry between the lungs. Fluid, such as blood, mucus, or tumor, are radiodense making the area appear white. Air filling appears black on the X-ray. As you examen the lungs, check for areas of opacity or patchy shadows, examen the vasculature and look for areas of consolidation. Also, look for Kerley lines, thin linear opacities that signal pulmonary edema and suggest congestive heart failure.

Gastric Fundus

Just below the heart, you should note the presence of a gastric bubble. Assess the amount of gas present.

Hilum and Mediastinum

Look at the hilum, the area of the lung containing the pulmonary arteries and main bronchus. The left lung hilum should be slightly higher than the right. Specifically, check for any visible lymph nodes. Calcified lymph nodes can be a sign of prior tuberculosis infection.

Instrumentation

Are there any tubes, IV lines, EKG leads, surgical drains, or a pacemaker present on the X-ray? If so, are they properly positioned? Make note of these in your report.

Reading chest X-rays is an art and can be a difficult skill to master. With some effort, time and practice, you will hone your skills and become an X-ray interpretation expert.

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