Chapter 9: Assessing the Fetus

Assessing the Fetus establishes a clear distinction between screening procedures, which identify populations at risk for specific conditions like trisomies, and diagnostic assessments, such as amniocentesis and chorionic villus sampling (CVS), which provide definitive confirmation of genetic or chromosomal anomalies. Central to fetal evaluation is obstetric ultrasound, categorized into standard, limited, or specialized levels, utilizing 2D, 3D, and 4D imaging to assess fetal anatomy, growth, and placental placement. The text details various screening markers, including nuchal translucency and maternal serum analytes like alpha-fetoprotein (AFP) and human chorionic gonadotropin (hCG), alongside advanced cell-free DNA (cDNA) testing. For late-pregnancy management, the chapter explores the assessment of fetal lung maturity through surfactant analysis, focusing on the lecithin-to-sphingomyelin (L/S) ratio and the presence of phosphatidylglycerol (PG). Furthermore, it outlines antepartum surveillance techniques designed to detect fetal hypoxia and prevent stillbirth, including maternal fetal movement counting, the nonstress test (NST), and the contraction stress test (CST). Comprehensive evaluations are conducted via the biophysical profile (BPP), which scores fetal breathing, movement, tone, and amniotic fluid volume to reflect central nervous system integrity, as well as Doppler flow studies that analyze vascular resistance in the umbilical arteries. Collectively, these diagnostic and screening tools empower healthcare teams to manage high-risk pregnancies and facilitate informed decision-making for expectant families.