The prevalence of congenital anomalies of the central nervous system varies in different epidemiologic studies, mostly as a consequence of the type of ascertainment and the length of follow up. The clinical role of sonographic biometry of the fetal cranium is well established. Biparietal diameter, head circumference, and transverse cerebellar diameter are currently used for assessing gestational age and fetal growth and identifying cranial abnormalities. Anencephaly and spina bifida comprise the majority of neural tube defects. In the 20 plus years since maternal serum alpha-fetoprotein (MSAFP) was recommended in United States for the general population, significant changes in the use of ultrasound and better understanding of the factors that place a woman at increased risk of bearing a child with spina bifida (and thus a candidate for diagnostic testing and not screening) have changed the utility of MSAFP screening. Amniotic fluid evaluation of alpha-fetoprotein and the role of fetal surgery for neural tube defects (NTDs) are also discussed.Read More

A number of interventions are available to reduce morbidity and mortality in fetuses with intrauterine growth restriction (IUGR); but these can only be implemented appropriately with timely diagnosis and monitoring. Prenatal diagnosis of these conditions can aid in decision making concerning the timing and route of delivery, thereby reducing perinatal risk. Regulation of fetal growth is multifactorial and complex. Optimal fetal development depends on genetically predetermined growth potential, and is modulated by fetal, maternal, placental, and environmental factors. The role of Doppler ultrasonography is also discussed. Abnormally small fetuses as a group have a relatively poor prognosis because some of the causes of subnormal size, such as inadequate supply of oxygen and nutrients through the placenta, chromosomal anomalies, and infections, adversely affect fetal outcome. Disturbances of fetal growth -- intrauterine growth restriction (IUGR) and macrosomia -- are associated with increased risk of perinatal morbidity and mortality. Prenatal diagnosis of these conditions can aid in decision making concerning the timing and route of delivery, thereby reducing perinatal risk.Read More

The availability of prenatal diagnosis for a wide range of disorders has been a major advance in the area of reproductive genetics. Ultrasound has played a central role in the development of the various approaches to prenatal diagnosis. In addition, integration of a genetics-based prenatal diagnosis program with tertiary ultrasound has been shown to increase the accuracy of diagnosis when compared with ultrasound alone. The purpose of this document is to focus on the epidemiology of genetic defects and include a description of the various prenatal diagnostic procedures in use.Read More