B lines
B lines are
1. hyperechoic lines originating at the pleura and extending down the length of the screen.
2. they move with respiration
3. they erase A lines
4. the are dynamic (can increase or decrease over time)
Similar to absent pleural sliding, differentiating the causes of B lines can be done by considering the clinical presentation, distribution of B lines (upper vs lower zones; unilateral vs bilateral) and the pleural thickness and character.
In most cases except pulmonary oedema and early infection or pulmonary embolus, the pleura is thickened or irregular
THIN PLEURA
Unilateral
early infection
Bilateral
Pulmonary Oedema
THICK/ IRREGULAR PLEURA
Unilateral
infection
contusion
malignancy
early pulmonary embolus
Bilateral
- pulmonary fibrosis (upper or lower zones)
- ARDS (skip lesions)
- bilateral infection (viral, covid (lower zones))
- pneumonitis
- bilateral contusions
- mets (usually consolidations also seen)
- miliary TB