Challenge of determining true outcome of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) remains one of the most challenging conditions to manage in neonatology and neonatal surgery. Despite significant advances in antenatal detection, antenatal therapy, neonatal intensive care and neonatal surgery, there is a significant mortality rate due to the combination of pulmonary hypoplasia, cardiac dysfunction and pulmonary hypertension. One of the major deficiencies in the literature has been a lack of high quality, multicentre data with a complete population denominator to accurately reflect the prognosis of this condition. Such studies would aid parental counselling, guide therapy and provide benchmarking data for clinicians and centres. The paper by Long et al 1 is a valuable contribution to the current evidence base, but we must be cautious in interpreting the presented data as true population outcomes. This paper is a prospective study of a cohort of infants who presented to paediatric surgical units in the UK and Ireland with diaphragmatic defects over an 18-month period during 2009–2010. The authors used robust methodology of case ascertainment, supported by the National Perinatal Epidemiology Unit, where local clinicians returned cards on a monthly basis. The data describe 219 live-born infants with an antenatal detection rate of 61%. This reflects 134 antenatally diagnosed CDH cases in 18 months. For the first 12 months of this study, the UK Obstetric Surveillance System (UKOSS) was conducting a study for pregnancies affected by CDH. Although these data have not yet been published, they identified 179 pregnancies in this period (https://www.npeu.ox.ac.uk/research/ukoss-cdh-174). Before discussing the outcome of postnatal surgical management, we should question why only approximately 50% of antenatally diagnosed cases have presented to surgical units postnatally to be included in the presented paper. Possible explanations include terminations of pregnancy and antenatally diagnosed newborns not reaching surgical centres. Modern management of CDH starts …