Congenital diaphragmatic hernia: the hidden mortality.

From 1969 to 1975, 33 cases of congenital diaphragmatic hernia (CDH) were treated at the National Hospital of Norway with a "visible" or operative mortality of 30%. At least 37 additional infants with CDH who died soon after birth and did not come to the attention of a major referral center were identified retrospectively from a comprehensive survey of neonatal deaths. CDH occurred at least once in every 5455 live births and the "true" mortality was 66%. More than half of the infants born with CDH during this 6-yr period died before they could be treated, contributing to a substantial "hidden" mortality.