Fetal hemivertebrae: associated anomalies, significance, and outcome.

OBJECTIVE: To study fetuses who had the sonographic diagnosis of hemivertebrae made in utero (excluding open neural tube defects) and to determine the incidence of associated anomalies, karyotypes, and neonatal outcome.
METHODS: Twenty-seven fetuses with sonographically detected vertebral abnormalities (excluding neural tube defects) and postnatal follow-up were included in the study. Associated structural defects and karyotypic anomalies were tabulated. The outcome for fetuses with isolated vertebral abnormalities on prenatal sonogram was compared with that of fetuses with associated anomalies.
RESULTS: Eleven of 27 fetuses had hemivertebrae as the only sonographic anomaly. Nine of the 11 were live-born with a good outcome; one patient elected pregnancy termination, and one fetus died of sepsis after premature rupture of the membranes. Sixteen fetuses had other anomalies including cardiac, intestinal, renal, intracranial, and limb anomalies. Seven of these 16 had Potter syndrome, two of whom also had sacral agenesis. Only five of those with additional anomalies survived; five died and six pregnancies were electively terminated. Because four of the six aborted fetuses had Potter syndrome (renal dysgenesis), a lethal malformation, a total of at least nine of the 16 fetuses with other anomalies would not have survived. All seven fetuses with severe oligohydramnios had lethal anomalies. Eighteen fetuses underwent karyotyping (including all those with isolated vertebral anomalies), and all had normal karyotypes.
CONCLUSION: Our study suggests that sonographically diagnosed, isolated fetal vertebral anomalies carry a good prognosis and the likelihood of a normal karyotype. The presence of associated anomalies reduces the survival to 50%, and when accompanied by significant oligohydramnios, the mortality is 100%.