Background: Delayed postnatal removal of lung liquid may result in respiratory distress, which is more common in infants born by cesarean section. Vertical artefacts (B-lines) arising from the lung surface in lung ultrasound have been shown to correlate with the liquid content of the lungs. Objectives: We studied whether lung ultrasound could be used for the assessment of postnatal lung liquid in healthy term infants born vaginally and by cesarean section. Methods: Lung ultrasound was performed 1, 3 and 24 h after birth to 22 vaginally born infants and 20 infants born by elective cesarean section. The abundance of B-lines was scored for each infant and time point by two independent observers blinded to the mode of delivery and time point on the examination on a five-step scale. Results: In both groups, a significant decrease in abundance of B-lines, indicative of lung liquid absorption, was observed during the first 24 h. 3 h after birth cesarean section was associated with significantly higher lung liquid content than vaginal delivery. Conclusion: The noninvasive bedside ultrasound method for estimation of lung liquid is a promising tool for the early identification of infants at risk for pulmonary maladaptation.

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