Prenatal diagnosis of osteogenesis imperfecta.

The lethal perinatal types (II A-C) of osteogenesis imperfecta are reported to occur in approximately 1:55000 births. We here present three cases in three unrelated families, diagnosed by antenatal ultrasound within one year. A reliable diagnosis of the lethal perinatal type of osteogenesis imperfecta can be made by ultrasound examination during the 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 dysplasia, but is not diagnostic for osteogenesis imperfecta. The diagnosis is confirmed by postmortem examination including radiography and biochemical studies of cultivated fibroblasts from the fetus. Although rare, this lethal condition should be recognized when an ultrasound examination is performed, to prevent unnecessary obstetric intervention. In families with a previously affected fetus, prenatal diagnosis by first trimester transvaginal ultrasound investigation or chorionic villus sampling should be discussed.