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Prenatal
Second Trimester Screening
Question | Answer |
---|---|
Down syndrome incidence | 1 in 800 |
13% of all pregnant females are... | over the age of 35 |
% of DS cases born to AMA patients | 25-30 |
AFP is made where? | fetal yolk sac and fetal liver |
AFP peaks during what weeks gestation | 12-14 |
Factors that influence MSAFP values | 1. Gestational age 2. number 3. maternal age 4. maternal race 5. maternal wt 6. IDDM |
Causes of ELEVATED MSaFP | 1. Normal variant 2. Underestimation of gestational age 3. Multiples 4. Overest. of maternal wt 5. Poor placental function 6. ONTD 7. VWD 8. Renal Anomalies 9. Oligohydramnios 10. Congenital skin DOs 11. Bleeding 12. IUFD 13. Maternal DOs |
hCG | high in DS and best marker for DS |
uE3 | Fetoplacental hormone which helps stimulate the endometrium and augment uterine blood flow. |
uE3 levels in DS | are 25-30% lower |
uE3 is the best marker for... | bad dates and trisomy 18 |
DIA | is a glycoprotein of placental origin similar to hCG that is twice as high in DS pregnancies |
Causes of LOW MSAFP | 1. Overestimation of dates 2. Underestimation of maternal weight 3. Normal variant 4. IUFD 5. IDDM 6. SGA 7. DS or other aneuploidy |
Advantages of MSAFP screening | 1. General for all 2. NTD 3. VWD 4. Fetal distress or demise 5. Multiparity 6. Trisomy 21 or 18 7. Nephrosis |
Racial differences in AFP | African Americans and IDDM Women have higher MSAFP levels |