Epidemiological study of congenital diaphragmatic defects with special reference to aetiology.

Congenital diaphragmatic defects (CDD) are easily accessible to ultrasonographic diagnosis. In spite of progress in the management of prenatally detected cases, the mortality rate for CDD remains high. The prognosis depends mainly on the severity of fetal lung hypoplasia but is also linked to the associated malformations. We report on 77 cases of CDD ascertained between 1982 and 1988 from 136,161 consecutive births in the Bouches du Rhône area. The spontaneous perinatal mortality rate was 61% with 28 early post-natal deaths and 14 stillbirths. Eight pregnancies were terminated after prenatal diagnosis. The diaphragmatic defect was associated with other congenital anomalies in 33 cases, more often among stillborn (92.8%) than liveborn infants (23.6%). A chromosomal abnormality was present in 9 cases representing 11.6% of all CDD and in 27.2% of cases with other anomalies. A Mendelian disorder was present in 9 cases (eight Fryns syndrome and one Fraser syndrome). This study underlines the necessity of a systematic work up of prenatally diagnosed cases, including fetal karyotyping and analysis of associated malformations in order to adapt the management of the pregnancy and delivery to the prognosis.