The evaluation of the lung by ultrasound is an adjunct tool to the clinical assessment. Among different hallmarks at lung ultrasound, B-lines are well known artifacts which are not correlated to identifiable structures but can be used as an instrument for pathological classification. Multiple B-lines are the sonographic sign of lung interstitial syndrome with a direct correlation between the number of B-lines and the severity of the interstitial involvement of lung disease. In neonatology and paediatrics, the quantitative assessment of B-lines is questionable as opposed to in adult medical care. Counting B-lines is an attempt to enrich the clinical assessment and clinical information, and not simply arrive at a dichotomous answer. A semiquantitative or quantitative B-lines assessment was shown to correlate with fluid overload and demonstrated prognostic implications in specific neonatal and paediatric conditions. In neonatology, the count of B-lines is used to predict the need for admission in neonatal intensive care unit and the need for exogenous surfactant treatment. In paediatrics, the B-lines count has the role of quantifying hypervolemia in infants and children receiving dialysis. B-lines as predictors of length of stay in the paediatric intensive care unit after cardiac surgery, as a marker of disease severity in bronchiolitis, or as an indicator of lung involvement from SARS-CoV-2 infection are speculative and not yet supported by solid evidence. Lung ultrasound with the quantitative B-lines assessment is promising. The current evidence allows to use the quantification of B-lines in a limited number of neonatal and paediatric diseases.

Background: Lung ultrasound (US) proved useful in patients with COVID-19, but limited data are available about its use in affected children. Aim: Lung ultrasound (US) is in the front door in the assessment of patients with coronavirus disease 19 (COVID-19), but limited data are available about its use in affected children. We aimed to describe lung US features and discuss its potential applications in COVID-19 children considering the usually mild disease course. Methods: We performed lung US to children with COVID-19 admitted between March 1st and April 27th, 2020. Clinical and radiological data were collected. One or more subsequent lung US were obtained from all subjects. Results: A series of 13 confirmed COVID-19 children were recruited. 8/13 patients showed signs of respiratory interstitial syndrome as for focal or coalescent B-lines or white lung, also in the absence of relevant clinical symptoms. Conclusions: As clinical characteristics of pediatric COVID-19 differ from adults, it is of interest to determine whether pediatric lung US shares the same imaging pattern of adults and whether COVID-19 pneumonia may differ from other virus pneumonia. Our small series highlighted that lung US documented signs of interstitial pneumonia in paucisymptomatic or asymptomatic pediatric patients. In conclusion, we pinpoint the usefulness of point of care lung US for the evaluation of infected children correlated with clinical information.