Neonatal respiratory distress syndrome: Chest X-ray or lung ultrasound? A systematic review

Background and aim: Neonatal respiratory distress syndrome (NRDS) is a leading cause of morbidity in preterm new-born babies (< 37 weeks gestation age [GA]). The current diagnostic reference standard includes clinical testing and chest radiography (CXR) with associated exposure to ionising radiation. The aim of this review was to compare the diagnostic accuracy of lung ultrasound (LUS) against the reference standard in symptomatic neonates of ≤ 42 weeks GA. Methods: A systematic search of literature published between 1990 and 2016 identified 803 potentially relevant studies. Six studies met the review inclusion criteria and were retrieved for analysis. Quality assessment was performed before data extraction and meta-analysis. Results: Four prospective cohort studies and two case control studies included 480 neonates. All studies were of moderate methodological quality although heterogeneity was evident across the studies. The pooled sensitivity and specificity of LUS were 97% (95% confidence interval [CI] 94%-99%) and 91% (CI: 86%-95%) respectively. False positive diagnoses were made in sixteen cases due to pneumonia (n=8), transient tachypnoea (n=3), pneumothorax (n=1) and meconium aspiration syndrome (n=1); the diagnoses of the remaining three false positive results were not specified. False negatives diagnoses occurred in nine cases, only two were specified as air-leak syndromes. Conclusions: LUS was highly sensitive for the detection of NRDS although there is potential to miss co-morbid air-leak syndromes (ALS). Further research into LUS diagnostic accuracy for neonatal ALS and economic modelling for service integration is required before LUS can replace CXR as the imaging component of the reference standard.