What Is the Sail Sign on CXR?

The Sail Sign on CXR

When it comes to interpreting chest X-rays (CXR), radiologists and healthcare professionals often look for specific signs that can indicate certain conditions or abnormalities. One such sign is the “Sail Sign.” This article will delve into what the Sail Sign is and its significance in diagnosing certain medical conditions.

Understanding the Sail Sign

The Sail Sign refers to a radiographic finding seen on a chest X-ray that resembles a sail. This sail-like appearance is created by the elevation of the left mainstem bronchus due to an underlying pathology.

Typically, the left mainstem bronchus descends below the level of the carina, which is where it splits into smaller bronchi leading to each lung. However, in cases where there is an abnormality causing displacement or obstruction, the left mainstem bronchus may appear elevated above its usual position.

Causes of the Sail Sign

The Sail Sign can be caused by various conditions, including:

  • Masses: Tumors or masses located near or compressing the left mainstem bronchus can cause it to be displaced upward.
  • Pneumothorax: The accumulation of air in the pleural cavity can cause lung collapse and subsequently shift structures within the chest cavity, including the left mainstem bronchus.
  • Atelectasis: Atelectasis refers to a partial or complete collapse of a lung or lobe. It can lead to displacement of nearby structures, resulting in a sail-like appearance on CXR.
  • Pulmonary fibrosis: In cases of pulmonary fibrosis, scarring of lung tissue can cause distortion and displacement of the left mainstem bronchus.

Significance in Diagnosis

The presence of the Sail Sign on a chest X-ray can provide valuable information to healthcare professionals in diagnosing underlying conditions. By identifying the sail-like appearance, radiologists can narrow down potential causes and recommend further diagnostic tests or interventions.

For example, if a mass is suspected to be the cause of the Sail Sign, additional imaging studies such as computed tomography (CT) scans may be ordered to obtain more detailed information about the mass’s size, location, and characteristics. Similarly, if pneumothorax is suspected, a chest CT or ultrasound may be performed to confirm the diagnosis.


The Sail Sign on CXR is an important radiographic finding that can indicate various underlying conditions affecting the left mainstem bronchus. Understanding its significance and causes enables healthcare professionals to make accurate diagnoses and provide appropriate treatment plans for patients.

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Daniel Bennet