Table 1.
Categories of probability of the disease based on patterns of LUS findings
| Category | LUS findings |
|---|---|
| A-Low probability of COVID-19 disease (normal lungs) | Regular sliding |
| A-lines observed over the whole chest | |
| Absence of significant B-lines (i.e., isolated or limited to the bases of the lungs) | |
| B-Pathological findings on LUS but diagnosis other than COVID-19 most likely | Large lobar consolidation with dynamic air bronchograms |
| Large tissue-like consolidation without bronchograms (obstructive atelectasis) | |
| Large pleural effusion and consolidation with signs of peripheral respiratory re-aeration (compressive atelectasis) | |
| Complex effusion (septated, echoic) and consolidation without signs of re-aeration | |
| Diffuse homogeneous interstitial syndrome with separated B-lines with or without an irregular pleural line | |
| Patterns suggestive of specific diagnoses: | |
| Cardiogenic pulmonary edema: diffuse B-lines with symmetric distribution and a tight correlation between the severity of B-lines and the severity of respiratory failure (anterior areas involved in the most severe conditions); in this case distribution of B-lines is uniform and gravity related; extending the sonographic examination to the heart will support the alternative diagnosis | |
| Pulmonary fibrosis and interstitial pneumonia from alternative common viruses: the B-lines pattern has greater spread and there are no or limited “spared areas” (alternating normal A-lines pattern) | |
| Chronic fibrosis: diffuse B-lines with clinical severity mismatch and with diffuse irregularity of the pleural line | |
| C-Intermediate probability of COVID-19 disease | Small, very irregular consolidations at the two bases without effusion or with very limited anechoic effusion |
| Focal unilateral interstitial syndrome (multiple separated and/or coalescent B-lines) with or without irregular pleural line | |
| Bilateral focal areas of interstitial syndrome with well-separated B-lines with or without small consolidations | |
| D-High probability of COVID-19 disease | Bilateral, patchy distribution of multiple cluster areas with the light beam sign, alternating with areas with multiple separated and coalescent B-lines and well-demarcated separation from large “spared” areas |
| The pleural line can be regular, irregular and fragmented | |
| Sliding is usually preserved in all but severe cases | |
| Multiple small consolidations limited to the periphery of the lungs | |
| A light beam may be visualized below small peripheral consolidations and zones with irregular pleural line |