Background: Pulmonary hypoplasia is the main cause of mortality in isolated congenital diaphragmatic hernia (CDH) and its prediction is paramount when counseling parents. We sought to identify antenatal parameters that predicted neonatal mortality in CDH.
Method: Search was conducted in MEDLINE, EMBASE, Cochrane Database of Systematic reviews, PubMed, Scopus, and Web of Science on the ability of lung-to-head ratio (LHR), observed-to-expected LHR (o/e LHR), total fetal lung volume (TFLV), o/e TFLV, percentage predicted lung volume (PPLV) and degree of liver herniation to predict neonatal morbidity and mortality in fetuses with CDH. Primary outcome was perinatal survival and secondary was the use of extracorporeal membrane oxygenation (ECMO).
Results: Until April 2016, 1067 articles were found, of which 22 were included in our meta-analysis. This showed that the odds of survival with LHR <1.0 and liver herniation on ultrasound were 0.14 (CI 0.10-0.27) and 0.21 (CI 0.13-0.35) respectively. Mean LHR, o/e LHR, absolute TFLV, o/e TFLV, PPLV and liver herniation all predicted survival, however o/e LHR and o/e TFLV performed best in this prediction. When the longest diameter measurement method was used, the o/e TFLV (summary area under curve (AUC) 0.8) was slightly superior to o/e LHR (summary AUC 0.78). This difference disappeared when LHR was measured by the trace method. The most discriminatory threshold for O/E LHR and O/E TFLV was 25%. LHR <1 was predictive of extracorporeal life support (ECLS) use.
Conclusion: O/E LHR, o/e TFLV (thresholds of 25%) and liver herniation are good predictors of mortality in CDH.
Level of evidence: Level II Type of study: Systematic review and meta-analysis.
Keywords: Congenital diaphragmatic hernia; Lung-head ratio; Outcomes; Prenatal diagnosis; Total fetal lung volume.
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