Ultrasound Level 1 Tutorial: Lung Ultrasound
Tutorial: Lung Ultrasound
Learn ultrasound of the lung. Identify pneumothorax, pleural effusions and wet lungs.
How to level up?
Develop your skills by completing our Practice Cases!
Tutorial: Lung Ultrasound B lines
Times Practiced
Cases Completed
1h 24m
Total Time spent
1m 24s
Average Time
B lines

B lines

B lines are artifacts seen within the lung. Like "A lines", they are also a reverberation artifact, but are a special kind of reverberation called "ring down".

They look like this (outlined by yellow lines):
   B lines on ultrasound

How they are formed:

Remember for A lines, the reverberation occured between the parietal pleura and the ultrasound probe. In B lines, the reverberation occurs betwen the parietal pleura and the visceral pleura. The distance between these 2 pleural surfaces is very short, so the spacing between all the reverberation lines is very very short. In fact, it is so short that the lines merge with each other and make a "white" shaded appearance, as you can see above.

B lines are created when there is an abnormality of the visceral pleura. The most common abnormality is that the visceral pleura is thickened by fluid. This might be fluid from heart failure, or fluid from inflammation. This thickened, abnormal visceral pleura vibrates in response to the ultrasound beam and the vibrations cause the reverberation artifact. The vibration is continuous, so the B lines continue all the way down to the bottom of the ultrasound image. The ultasound machine cannot determine the distance to an object when it is continuously vibrating.

Very important details:
  • B lines are abnormal
  • B lines require an interaction between the visceral and parietal pleura. Therefore, a pneumothorax or pleural effusion will prevent B lines from forming
  • B lines will obliterate A lines
  • B lines will move if lung sliding is present
  • B lines are perpendicular (straight down) from the pleura
  • B lines extend all the way to the bottom of the screen
  • B lines are similar, but different than comet tails (see next lesson)

B lines can be caused by:
  • congestive heart failure (CHF)
  • pneumonia
  • pneumonitis
  • ARDS
  • lung contusion
  • neoplasia
  • ARDS
  • less commonly:
    • pulmonary fibrosis
    • atalectasis
    • pulmonary embolism