Prevalence of aneuploidy and additional anatomic abnormalities in fetuses with open spina bifida: Population based study in Utah

Data were used to determine the population prevalence of aneuploidy and add itional anatomic abnormalities in fetuses with open spina bifida. The abili ty of sonography to predict aneuploidy and identify additional anatomic abn ormalities in euploid fetuses was assessed. All cases of spina bifida occur ring in the state of Utah from 1995 through 1997 were reviewed using Utah B irth Defect Network data, including stillborn, liveborn, and terminated cas es. Chromosomes were known in 45 of 51 cases of open spina bifida. Of the 4 5 fetuses, 6 (13%) were aneuploid. Major anatomic abnormalities were presen t in four of six (67%) cases, and two of six (33%) cases had additional ano malies that could be missed sonographically. Of 39 euploid fetuses, 12 (31% ) had additional abnormalities, but only half likely would be detected sono graphically. Our 4% risk of aneuploidy in sonographically isolated spina bi fida is substantially higher than the risk associated with advanced materna l age (0.37%).