Prenatal detection of pulmonary hypoplasia in fetuses with congenital diaphragmatic hernia: a systematic review and meta-analysis of diagnostic studies.

BACKGROUND Fetuses with congenital diaphragmatic hernia (CDH) are at risk of death from pulmonary hypoplasia at birth. OBJECTIVE To determine the value of prenatal imaging parameters for predicting lethal pulmonary hypoplasia in fetuses with CDH. SEARCH STRATEGY Relevant papers were identified by searching MEDLINE (1966-2008), EMBASE (1988-2008) and the Cochrane Library (2008 issue 3). SELECTION CRITERIA Selected studies examined diagnostic tests for the prenatal prediction of lethal pulmonary hypoplasia in fetuses with CDH. The primary outcome measure was perinatal survival. RESULTS Twenty-one studies fulfilled the entry criteria, of which six examined entirely unique heterogeneous parameters and the remaining 15 examined lung-head ratios (LHR) and/or the presence of liver in the fetal thorax. The strongest association was that of LHR > or = 0.6 compared to 1.0 (OR: 5.07; 95% CI: 2.94-8.74). The finding of liver in the fetal chest was a poor prognostic feature (survival OR: 0.32; 95% CI: 0.21-0.49). CONCLUSION In CDH, LHR and the presence of liver in the fetal thorax may be a useful predictive indicator of perinatal survival. Future usage of developing techniques needs careful evaluation prior to usage to guide therapy.