The hidden mortality of congenital diaphragmatic hernia: a 20-year review.

AIMS: The true mortality associated with congenital diaphragmatic hernia (CDH) is hidden because survival analyses do not include fetuses with CDH. A retrospective review of all postmortems (PMs) with a diagnosis of CDH over a 20-year period was carried out to highlight this hidden mortality and also measure the nature and number of associated anomalies.

METHODS: Postmortem case record details were reviewed for the period January 1986 to December 2005. Data were collected on live birth, stillbirth, therapeutic abortion, and spontaneous abortion.

RESULTS: There was a decline in the annual number of PMs during the period of the study. The median for the four 5-year intervals being 609 (570-657), 528 (488-565), 515 (413-537), and 373 (357-388). A total of 130 PMs were identified, which included a diagnosis of CDH; 97 (75%) were left sided, 22 (17%) were right sided, and 11 (8%) were bilateral. There were 69 live births, 46 therapeutic abortions, 10 stillbirths, and 5 intrauterine deaths; 22% were right sided/bilateral in the live and therapeutic abortion groups, whereas 53% were right sided/bilateral in the latter 2 groups. Of 130, 82 (63%) had major associated anomalies, and 50% of these had at least 1 further major anomaly. The commonest categories of anomalies were cardiac (30), gastrointestinal/abdominal wall defect (28), and neural tube defects (25).

CONCLUSIONS: The true incidence of CDH is considerably higher than that seen in neonatal surgical practice. The decline in number of PMs in our region will exacerbate the underestimation of the true incidence. There is a higher incidence of right-sided/bilateral hernias and more than one major anomaly in those who die in utero.