The sonographic findings in four infants with Noonan's syndrome are described. All four fetuses had cystic hygromata located laterally along the cervical spine and normal karyotypes. Three of the four pregnancies were complicated by polyhydramnios and those three fetuses had associated pleural effusions. One fetus developed frank hydrops and did not survive, a clinical course that appears to be part of the clinical spectrum of Noonan's syndrome. The diagnosis of Noonan's syndrome was given serious consideration prenatally based on the sonographic findings and normal karyotype and confirmed at birth in all four cases. Three of the infants survived.

Twelve cases of fetal trisomy syndromes are reported in which prenatal sonographic findings were highly suggestive of the chromosomal abnormality. The abnormal appearance on the sonogram led to karyotype studies in ten fetuses and to appropriate obstetrical management. The sonographic abnormalities pertained to the extremities and face of the fetus.

Massive intracranial hemorrhage was diagnosed in utero in a 27-week-old fetus. The subsequent development of hydranencephaly was monitored by ultrasound until term.

The pren;ital sonogrnphi<.: diagnosis of spinal almormalities associated with neural tuhe element mulformations has heen well described ; however, the diagno. -;is of fotal skeletal anomalies of the vertehral bodies with a neurologically intact spine has received little attention. Three cases of congenital hemivertehra identified sonogruphicnll)' in fotuses between 17 and 28 weeks' gestation are reportecL One of the fotuses also had associated abnormalities involving the heud and extremities. The prenatal diagnosis of congenital hemivertebrn should alert the sonogrnpher to search for other congenital defects and for orthopedic complications of vertebral hody malformations in childhood. Prior knowledge of the presence of an abnormal vertebral body can alel't the pediatrician to watch for early signs of problems such as scoliosis or kyphoscoliosis, and to plun surgery if necessary.