PRENATAL-DIAGNOSIS OF OSTEOGENESIS IMPERFECTA

The lethal perinatal types (II A-C) of osteogenesis imperfecta are rep orted to occur in approximately 1:55000 births. We here present three cases in three unrelated families, diagnosed by antenatal ultrasound w ithin one year. A reliable diagnosis of the lethal perinatal type of o steogenesis imperfecta can be made by ultrasound examination during th e second trimester, by identification of fractures of the long bones. The compression of the fetal head by the ultrasound probe and the low echogeneity of the cranium, should raise the suspicion of skeletal dys plasia, but is not diagnostic for osteogenesis imperfecta. The diagnos is is confirmed by postmortem examination including radiography and bi ochemical studies of cultivated fibroblasts from the fetus. Although r are, this lethal condition should be recognized when an ultrasound exa mination is performed, to prevent unnecessary obstetric intervention. In families with a previously affected fetus, prenatal diagnosis by fi rst trimester transvaginal ultrasound investigation or chorionic villu s sampling should be discussed.