Equivocal-suspicious—the presence of intermittent late decels or significant variable decels; requires follow-up testing. o Risks: Hyperstimulation Amniocentesis/CVS/Fetal Fibronectin/Evaluation of Fetal Lung Maturity • Maternal serum alpha protein (MSAFP) o Component of the Quadruple check or Quad Screen that utilizes the multiple markers, including alpha-fetoprotein (AFP), hCG, diamric inhibin-A, and estriol to screen pregnancies for neural tube defect (NTD), trisomy 21, and trisomy 18; use maternal blood – The quad screen is the most widely used test to screen for Down syndrome, trisomy 18, and neural tube defects. o MSAFP Definition— a screening test; not diagnostic; examines alpha - fetoprotein in the mother's blood during pregnancy – If the fetus has a NTD, AFP levels are elevated
– NTSs are the most common defect in U.S.A. and range from anencephaly to Spina bifida o significance: – levels increased with: anencephaly, multiples, fetal demise, multiples – levels decreased with: Down syndrome – When a fetal body wall defect is present, AFP leaks and is absorbed into the maternal circulation, causing the woman’s serum AFP level to rise. o accuracy = 98%; fairly accurate o Typically performed at 15-18 weeks gestation • Amniocentesis o Procedure used for genetic Dx o Between 15-20 wks. Gestation; won’t do in first trimester because of low AFV – Can make chromosomal and biochemical determinations: enzyme analysis, AFP, blood type, cytogenic, metabolic, and other DNA testing – Later in pregnancy, from 30 to 35 weeks’ gestation, amniocentesis may be done for lung maturity studies such as L/S ratio and presence of phosphatidylglycerol and phosphatidylcholine o Increases risk of infection, preterm labor (stimulate cramping and possibly contractions), physician could potentially stick the baby (U/S guided) should be clear, no blood, or infection Evaluation of Fetal Lung Maturity: • Lecithin/Sphingomylin: L/S Ratio- component of surfactant, indicates fetal lung maturity o Want a 2:1 ratio for fetal lung maturaty (want twice as much Lecithin as Sphingomylin) • Phosphatidylglycerol Levels (PG)—Phospholipid component of surfactant; released into amniotic fluid (AF) around 36 wks. when surfactant is released Other testing methods: • Chorionic Villus Sampling (CVS) o Detects genetic, metabolic, and DNA abnormalities; cannot detect NTDs o Obtain a small sample (5-40 mg) of chorionic billi from from the edge of the developing placenta o Needle inserted to withdraw chorionic villus; findings have implications for pregnancy termination (abortion); done in the 1 st trimester somewhere in 8-12 weeks – Villi in th chorion frondosum reflects fetal chromosome, enzyme, and DNA content • Fetal Fibronectin (fFN)—glycoprotein produced by trophoblast and other fetal tissues o The presence of cervicovaginal fFN between 20 and 34 weeks’ gestation has been shown to be a strong predictor of preterm delivery due to spontaneous preterm labor or premature ROM
– Positive findings = strong predictor of preterm labor or rupture of the
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- Fall '12
- Obstetrics, Fetal heart rate, fetal well-being, fetal lung maturity