Characteristics of B lines based on etiologya
| Cardiogenic pulmonary edema | Noncardiogenic diffuse pulmonary interstitial edema | Interstitial pneumonia or pneumonitis (bacterial, viral, or inflammatory) | Interstitial fibrosis | |
|---|---|---|---|---|
| Distribution | Diffuse Usually bilateral and symmetric Predominant in dependent regions | Diffuse or patchy Often asymmetric | Focal or patchy Usually asymmetric | Diffuse or patchy Variable symmetry |
| Spared areas | Absent | Often present | Present | Often present |
| Number of B lines | Variable | Variable | Variable | Variable |
| Pleura | Smooth | Irregular | Irregular | Irregular |
| Subpleural consolidations | Absent | Present | Present | Typically absent |
| Reduced lung sliding | Absent | May be present | May be present | May be present |
| Pleural effusion | Often present | Typically absent | May be present | Typically absent |
↵a Defining the terminology: diffuse = present throughout; patchy = present in many areas throughout, absent in other areas throughout; focal = present in one region but not in others; spared areas = regions of lung with A-line pattern (amid a background of B-line pattern).