Biochemcial Markers Flashcards
What is the prevalence of chromosomal abnormalities in early pregnancy loss?
50%
This statistic highlights the significant rate of chromosomal issues contributing to early pregnancy loss.
What percentage of stillbirths and neonatal deaths is attributed to chromosomal abnormalities?
6-11%
These figures indicate the impact of chromosomal anomalies on perinatal mortality.
What is the prognosis for children with Trisomy 21 in terms of life expectancy?
Mean survival 55 years
Children with Trisomy 21 typically experience moderate mental retardation and have a life expectancy that varies significantly.
What maternal age is considered for offering prenatal diagnosis?
35 years and older
Advanced maternal age is a key factor in assessing the risk of chromosomal abnormalities.
List the indications for prenatal diagnosis.
- Advanced maternal age
- Parental chromosome rearrangements
- Previous affected child
- Positive aneuploidy screening test
- Abnormal ultrasound findings
These indications help identify pregnancies at higher risk for genetic disorders.
What is the risk of Trisomy 21 at 35 years of maternal age?
1/270
The risk increases with maternal age, making screening essential.
What defines an ideal screening test?
- High sensitivity
- High specificity
- Positive early in gestation
- Easy
- Inexpensive
These characteristics ensure effective and reliable screening outcomes.
True or False: The age limit for offering prenatal screening is based on a biological difference.
False
The age limit is more about logistical concerns than biological differences.
What is the detection rate of the second trimester Down Syndrome screening for women younger than 35?
60%
This screening is performed between 16-20 weeks and is most accurate between 16-18 weeks.
What biochemical markers are used in the second trimester screening for Down Syndrome?
- Maternal age
- Alpha-fetoprotein (AFP)
- Beta-hCG (bhCG)
- Unconjugated Estriol (uE3)
These markers help calculate the risk of Down Syndrome in the fetus.
Fill in the blank: The risk of spontaneous fetal death for Trisomy 21 fetuses between 12 weeks and term is _______.
30%
This statistic emphasizes the risk associated with Trisomy 21 during pregnancy.
What is the risk of cardiac defects associated with Trisomy 21?
5-30%
Cardiac anomalies are commonly linked with chromosomal abnormalities.
What are the detection rates of biochemical markers according to maternal age for Down Syndrome?
- 20 years: 2.4% screen-positive rate, 41% detection rate
- 35 years: 14% screen-positive rate, 71% detection rate
- 40 years: 40% screen-positive rate, 91% detection rate
These rates illustrate how detection improves with maternal age.
What is the significance of Nuchal Translucency measurement in prenatal screening?
Increased measurement indicates higher risk for aneuploidies
Nuchal translucency is a key marker for assessing risks of chromosomal abnormalities early in pregnancy.
What is the fetal death risk associated with Trisomy 18 and Trisomy 13 fetuses between 12 weeks and term?
80%
This high rate underscores the severity of these conditions.
What is the effect of maternal age on serum screening detection rates?
Both detection rate and screen positive rate increase with maternal age
This relationship is important for risk assessment in prenatal care.
True or False: Ultrasound abnormalities involving a major organ indicate a low risk of aneuploidy.
False
Major organ abnormalities are significant markers for higher aneuploidy risk.
What is the role of Free beta-hCG in first trimester screening?
Consistently elevated between 8-13 weeks
Free beta-hCG is an important marker for assessing risk early in pregnancy.
What are common non-specific sonographic findings in first trimester screening?
- Embryo size
- Yolk sac size
- Persistent posterior fossa cysts
These findings can help identify potential issues but are not definitive on their own.
What is nuchal translucency (NT)?
A measurement used in prenatal screening to assess the risk of chromosomal abnormalities in a fetus.
What is the gestational age range for measuring nuchal translucency?
11 to 13 weeks (CRL 45-84mm).
What is the significance of a maximum NT measurement greater than 6 mm?
Indicates a 36x age-related risk for aneuploidy.
What is the false positive rate (FPR) for nuchal translucency screening?
2.5% to 9.3%.
True or False: Nuchal translucency measurements can vary due to differences in techniques.
True.
What is the sensitivity for Down syndrome (DS) detection with NT > 3.5 mm?
77%.
What is the relationship between NT thickness and maternal age regarding aneuploidy risk?
Higher NT thickness correlates with increased age-related risk.
List some congenital anomalies associated with abnormal nuchal translucency.
Down Syndrome, Patau Syndrome, Edward’s Syndrome, Turners Syndrome
- Obstructive uropathies
- Noonan syndrome
- Diaphragmatic hernia
- Renal anomalies
- Abdominal wall defect
- Rare genetic syndromes.
What is the role of nasal hypoplasia in prenatal screening?
Absent nasal bone is associated with increased risk for Down syndrome.
What is the recommended age for offering aneuploidy screening to all women?
Before 20 weeks of gestation.
What is the purpose of the Integrated Screen in prenatal care?
To adjust a woman’s age-related risk of having a child with Down syndrome.
What are the two strategies proposed in sequential screening?
- Stepwise sequential screening
- Contingent sequential screening.
How is fetal aneuploidy diagnosed?
AMNIOCENTESIS
– Offered between 15 and 20 weeks
– Cytogenic diagnosis accuracy (>99%)
– Fetal loss 0. 5%
– Transient vaginal spotting or leakage 1-2%
– Chorioamnionitis < 1 in 1,000
– Needle injuries to fetus are rare
– AF cell culture failure is uncommon
What is the pregnancy loss rate associated with early amniocentesis?
2.5%.
What is the fetal loss rate for chorionic villus sampling (CVS)?
0.6-0.8%.
Fill in the blank: The mean half-life for fetal DNA in maternal circulation is ______.
16.3 minutes.
What is the detection rate for fetal DNA in Down syndrome cases?
21% at a 5% false-positive rate.
Who is considered at risk for fetal aneuploidy?
- Women age 35 or older
- Previous pregnancies with autosomal trisomy
- Fetus with major structural defect.
What is a significant marker for preterm delivery in maternal circulation?
Increased levels of fetal DNA.
What screening tests are included in the Quad screen?
- AFP
- uE3
- hCG
- Inhibin A.
What condition is associated with a five-fold increase in fetal DNA in maternal samples?
Preeclampsia.
What is the purpose of fetal echo during the second trimester?
Recommended if abnormal NT is detected.
True or False: The absence of ultrasound evidence for Down syndrome decreases the risk sufficiently to avoid amniocentesis.
True.
What is the association between limb reduction and oromandibular defects?
The association is not clear.
What’s in the Intergrated Screen?
Integrated Screen:
1st trimester NT,
PAPP-A,
2nd trimester AFP,
uE3,
hCG,
Inhibin A
What’s in the Serum Integrated Screen?
• Serum Integrated screen:
1st trimester
PAPP-A, 2nd trimester hCG, uE3, Inhibin
A
