ITEMS IN AFP WITH MESH TERM:
ABSTRACT: Down syndrome (trisomy 21) is the most commonly recognized genetic cause of mental retardation. The risk of trisomy 21 is directly related to maternal age. All forms of prenatal testing for Down syndrome must be voluntary. A nondirective approach should be used when presenting patients with options for prenatal screening and diagnostic testing. Patients who will be 35 years or older on their due date should be offered chorionic villus sampling or second-trimester amniocentesis. Women younger than 35 years should be offered maternal serum screening at 16 to 18 weeks of gestation. The maternal serum markers used to screen for trisomy 21 are alpha-fetoprotein, unconjugated estriol and human chorionic gonadotropin. The use of ultrasound to estimate gestational age improves the sensitivity and specificity of maternal serum screening.
ABSTRACT: According to the American College of Obstetricians and Gynecologists, it has become standard in prenatal care to offer screening tests for neural tube defects and genetic abnormalities. There have been some changes in the recommended method of prenatal screening over the past few years, and research to improve detection rates with better combinations of maternal serum analytes is ongoing. The issues facing physicians are the sensitivity and specificity of multiple serum analyte combinations. The current maternal serum analytes in use in most areas are alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG) and unconjugated estriol. Measurement of AFP alone can detect the vast majority of neural tube defects and a small portion of trisomy 21-affected pregnancies in patients of all ages. Adding hCG and unconjugated estriol to this screen increases the rate of detection of trisomies 21 and 18. Counseling patients about the risks and benefits of such screening is important to provide a balanced discussion of screening issues.