In polytraumatized patients, a rib or sternal fracture can be visualized as a discontinuity in the anterior cortex of the bone. It may suggest internal injuries such as hemothorax or pulmonary contusion.

Ultrasound visualizes effusions directly, with hemothorax appearing as a heterogeneous fluid collection in the dependent portion of the lung.

Fig 1: Traumatic heterogeneous pleural effusion indicative of hemothorax.

Fig 2: Thoracic ultrasound revealing hemothorax, characterized by a heterogeneous fluid collection in the lung's dependent portion, in a patient with a history of trauma.

Ultrasound can detect pulmonary contusions as subpleural, irregular hypoechoic lesions with either indistinct or sharp margins. Some contusions may also appear as multiple B-lines, resembling those seen in alveolar-interstitial syndrome.

Fig 3: Subpleural irregular hypoechoic area following blunt trauma, suggestive of pulmonary contusion.

Pneumothorax, whether traumatic or nontraumatic, is characterized by the alternating presence and absence of lung sliding. The point where the healthy sliding lung meets the absent sliding in pneumothorax is referred to as the lung point. The more lateral or posterior the lung point on the thoracic wall, the larger the pneumothorax.

In M-mode (motion-mode), the absence of lung sliding is represented by the bar-code sign, which appears as uniform horizontal straight lines below the pleura, replacing the normal grainy appearance of the underlying lung.

In an infectious context, abolished lung sliding may also suggest pneumonia, particularly if accompanied by consolidation with air bronchogram (hyperechoic foci) and localized B-lines.

Fig 4: Hypoechoic area with multiple moving hyperechoic foci (air bronchogram) and associated pleural effusion, suggestive of pneumonia.

Although the A-profile is a normal finding, in non-traumatic acute dyspnea, pulmonary embolism must be ruled out. This involves assessing for thrombosed leg veins or confirming the diagnosis with a CT scan. Multifocal, triangular, heterogeneous hypoechoic lesions may indicate pulmonary infarctions.

Asthma or an acute exacerbation of chronic obstructive pulmonary disease may also present with an A-profile, as their pathophysiology involves airflow obstruction, which is not detectable on ultrasound.

Lung sliding with diffuse bilateral B-lines suggests interstitial pulmonary edema.

Cardiac findings can support the diagnosis of pulmonary thromboembolism, particularly when there are signs of right ventricular dysfunction, such as dilatation. If pulmonary edema is of cardiac origin, signs of cardiac dysfunction will also be present and easily detectable.