Prenatal Testing Flashcards
Question
Answer
A 42-year-old in your office who is now 5 weeks pregnant
with her fifth baby. She is very concerned regarding the risk of down syndrome because of her advance maternal age.
After extensive genetic counseling, she has decided to
undergo a second-trimester amniocentesis to determine
the karyotype of her fetus. Prior to performing the procedure, you inform the patient that all of the following are possible complications of the amniocentesis. EXCEPT:
a. Amniotic fluid leakage
b. Chorioamnionitis
c. Limb reduction defects
d. Cell culture failure
D. Cell culture failure
Williams, pg 293
. Amniotic fluid leakage
The risk of having a baby with down syndrome for a 30 yo woman increase
a. if the father of the baby is 40 yo
b. if her pregnancy has achieved by induction of
ovulation by menotropins (follistin, gonadal F)
c. if she has had a previous baby with triploidy
d. if she has had three first trimester spontaneous abortion
c. if she has had a previous baby with triploidy
Williams, pg 278
Other important fetal aneuploidy risk factors (other than age) include numerical chromosomal abnormality or structural chromosomal rearrangement in the woman or her partner or a prior pregnancy with autosomal trisomy or triploidy
a 24 yo white woman has a maternal serum a-fetoprotein (MAFP) at 17 weeks gestation of 6.0 mutliples of the median (MOM). The next step should be
a. A second MSAFP test
b. Ultrasound examination
c. Amniocentesis
d. Amniography
b. Ultrasound examination
Williams, pg 283
Most centers now use targeted sonography as the primary method to evaluate elevated MSAFP levels and as the prenatal diagnostic test of choice for neural-tube defects.
MSAFP level of 2.5 MoM as the upper limit of normal
Advantages of ultrasound nuchal translucency over
biochemical screening for down syndrome include
a. Uses transvaginal approach
b. More consistent measurements than lab
tests
c. Better in multiple gestation
d. Wide gestational age range
e. More convenient for patients
c. better in multiple gestation
Williams, pg 286
Sonography can augmesnt screening by providing acurate gestational age assessment by detecting multifetal gestations and by identifying major sturctural abnormalities and minor sonographic markers.
the embryonic neural tube is formed via neuralation, which involves shaping, folding, and midline fusion of the neural plate and is complete after how many days from conception?
a. 14 days
b. 21 days
c. 25 days
d. 35 days
d. 35 days
Williams, pg 192
NTDs result from incomplete closure of the neaural tube by the embryonic age of 26 to 28 days.
Presomite- 19 days
-differentiation of body stalk and en embryonic sac is formed
7 somites- 21 days
-neural groove begins forming
17 somites- 22 days
PERIODS:
- IMPLANTATION: 1-2 Weeks
- EMBRYONIC PERIOD/ ORGANOGENESIS: In here neural tube develops in the 3rd -4th week.
aneuploidy is typically associated with neural tube defects, EXCEPT:
a. trisomy 21
b. trisomy 18
c. turner syndrome
d. 46 XXY
c. turner syndrome
true regarding antenatal monitoring of neural tube
defects, EXCEPT:
a. fetal echocardiogram is requested for cardiac function and structure
b. amniocentesis should be considered for fetal karyotyping
c. antepartal serial ultrasound of femoral length alone to monitor fetal growth
d. determination of alpha feto protein is an integral part during antepartum
c. antepartal serial ultrasound of femoral length ALONE to monitor fetal growth
this form of neural tube defect appears as a wide
splaying of the vertebral arch with no visible covering
a. myelomeningocele
b. meningocele
c. anencephaly
d. myeloschisis
d. myeloschisis
pg 192
Myelomeningocele - herniation of a meningeal sac containing neural elements
Meningocele – is a birth defect where there is a sac protruding from the spinal column. The sac includes spinal fluid, but does not contain neural tissue. It may be covered with skin or with meninges
Anencephaly - is the absence of a major portion of the brain, skull, and scalp that occurs during embryonic development.
Myeloschisis - a developmental defect characterized by a cleft spinal cord that results from the failure of the neural plate to fuse and form a complete neural tube
herniation of a meningeal sac containing neural elements
a. myelomeningocele
b. meningocele
c. anencephaly
d. myeloschisis
a. myelomeningocele
birth defect where there is a sac protruding from the spinal column. The sac includes spinal fluid, but does not contain neural tissue. It may be covered with skin or with meninges
a. myelomeningocele
b. meningocele
c. anencephaly
d. myeloschisis
b. meningocele
the absence of a major portion of the brain, skull, and scalp that occurs during embryonic development.
a. myelomeningocele
b. meningocele
c. anencephaly
d. myeloschisis
c. anencephaly
combining both free beta hCG and pregnancy associated plasma protein –A alone can identify trisomy 21 in
how many percent?
a. 40-45%
b. 55-60%
c. 60-65%
d. 65-70%
d. 65-70% (should be 80-84%)
pg 280 Table 14-4 1st trim screen NT, hCG, PAPP-A = 80-84% 1st trim NT alone = 64-70%
the possible consequences of higher AFP or unexplained
elevation in AFP level in structurally normal pregnancy is
associated with development of
a. fetal growth restriction
b. polyhydramnios
c. placenta previa
d. abortion or 1st trimester loss
a. Fetal growth restriction
Williams, pg 283
Table 14-6
Adverse outcomes include fetal growth restriction, preeclampsia, pre-term birth, fetal demise, and stillbirth
Aneuploidy is typically associated with neural tube defect and is present in 10% of cases of
A. Trisomy 21
B. Trisomy 18
C. Turner Syndrome
D. 46XX
A. Trisomy 21
MSAFP is best measured during this time:
A. 12-14 weeks
B. 14-16 weeks
b. 14-16 weeks
Trisomy 21
Down Syndrome
Trisomy 18
Edward Syndrome
Trisomy 13
Patau Syndrome
45, X
Turner Syndrome
In addition to neural tube defects, elevated AFP and + acetylcholisterase are also present in other fetal obnormalities such as
. Ventral wall defects . Esophageal atresia . Fetal tetratoma . Cloacal extrophy . Skin abnormalities such as epidermolysis bullosa
Signs of Trisomy 18
Edward Syndrome
. Unusally small head
. Back of head is prominent
. Ears are malformed and low-set
. Mouth and jaw are small (may also have cleft palate)
. Hands are clenched into fists, and the index finger overlaps the other fingers
. Clubfeet (or rocker bottom feet) and toes may be webbed or fused
In addition to maternal age, other risk factors for down syndrom and other aneuploidy are
. Numerical chromosomal abnormality or structural chromosomal rearrangements in the woman or her parterner
. Prior pregnancy with autosomal trisomy or triploidy
What 4 structures do you look for in first trimester scan in sagittal section of the fetus?
. Nuchal translucency (most important)
. Nasal bone
. Skin - hyperechoic line
. Intracranial
