Fetal Well-Being Assessment and Prenatal Diagnosis Flashcards
Which is the most accurate estimate of the gestational age …?
Fetal crown–rump length (measured in the first trimester)
First trimester screening for aneuploidy includes …?
A combination of maternal age, pregnancy-associated plasma protein-A (PAPP-A), free β-human chorionic gonadotropin (β-hCG), and nuchal translucency (NT)
Second trimester screening for aneuploidy includes..?
A combination of
maternal serum α-fetoprotein (MSAFP),
total or free β-hCG,
unconjugated estriol (uE3), and
inhibin A (quad test);
it is less sensitive than first trimester screening.
The baby in-utero begins to experience the world through touch as early as……. weeks.
8 weeks ‘
At <9 weeks of gestation, if the CRL and LMP dates differ by >5 days, then which is considered to be accurate ..?
ultrasound is considered as the better estimate of GA
After 14 weeks, measurement of the………. is used to estimate GA.
head circumference (HC) and femur length (FL)
Additional fetal measurements, including biparietal diameter (BPD), abdominal circumference (AC), fetal long bones (i.e., femur, humerus, ulna, and tibia), and transverse cerebellar diameter, may also assist in the estimation of fetal GA.
First trimester aneuploidy screening is performed between. …….. weeks of pregnancy
11 and 13+6
Pregnancy-associated plasma protein-A (PAPP-A),
free β-human chorionic gonadotropin (β-hCG)
nuchal translucency (NT) on ultrasound
Conditions associated with decrease levels of PAPP-A (<0.415 MOM) ..?
Besides aneuploidy
fetal growth restriction (FGR),
preterm labor,
gestational hypertension,
preeclampsia (PE), and
ectopic pregnancy
PAPP-A is higher in…?
twin pregnancies
What is assessment tool for NT scan ..?
Ultrasonographic assessment of the fluid collected at the nape of the fetal neck behind the cervical soft tissue, NT, is a sensitive marker for aneuploidy
How to interpret the NT measurement ..?
It should be measured for a CRL between 45 and 84 mm
NT above the 95th centile for a particular CRL (2.1 mm for a CRL of 45 mm, and 2.7 mm for a CRL of 84 mm) is associated with an increased risk of aneuploidy
Risk of other anomalies in the fetus with an increased NT includes…?
cardiac defects
lymphatic defects
single-gene defects,
central nervous system (CNS) defects, and
skeletal and abdominal wall defects
Ultrasound for NT is best performed at what weeks of gestation..?
at 11 to 13+6
Other ultrasound findings in the first trimester fetus that may be associated with trisomy include…?
absent or hypoplastic nasal bone,
abnormal ductus venosus (DV) blood flow, and
triscuspid regurgitation.
What is OSCAR ….?
one-stop clinic for assessment of risk (OSCAR)—
It is practiced in centers where biochemistry is performed by 11 weeks and scan at 11 to 12 weeks and risk assessed after scan.
CVS is offered on the same day if risk is more than 1 in 100
What is Quadruple panel (quad test) …?
serum α-fetoprotein (MSAFP),
hCG (free β or total),
unconjugated estriol (uE3), and
inhibin A
In a pregnancy (fetus) with trisomy 21 quad test ….?
hCG (free β or total) and inhibin A levels are high,
MSAFP and uE3 levels are low
Trisomy 18 quad test ….?
Low levels of all serum biochemical markers
What percentage of fetuses with trisomy 21 will have a “positive” quadruple screen…?
80%
About MSAFP ..?
It is best measured between 15 and 22 weeks.
α-Fetoprotein (AFP) is secreted by the fetus and is present in the amniotic fluid and maternal serum
MSAFP elevated above 2.5 multiples of median (MOM) for the GA occurs in 70% to 85% of fetuses with open spina bifida and 95% of fetuses with anencephaly
USG signs in NTD ..?
Ultrasonography intracranial signs such as
changes in the head shape (lemon sign) or
deformation of the cerebellum (banana sign)
Which approach achieves the highest detection rate of trisomy 21 (97%) at a low screen-positive rate (2%)..?
Integrated screening.
It involves a first trimester ultrasound and maternal serum screening in both the first and second trimesters.
What is Sequential screening …?
Results indicating a high risk of trisomy 21 in the first trimester are declared, but the entire population is screened in the second trimester (stepwise sequential)
Stepwise screening ….?
First trimester screen, then quad screen for all
Contingent screening …?
First trimester screen, then quad screen only for intermediate/high risk
What is TIFFA …?
Mid-trimester (targeted imaging for fetal anomalies (TIFFA)] scan, between 18 and 22 weeks, has traditionally enabled imaging to screen and detect fetal structural anomalies.
Fetal echocardiogram (ECHO) for prenatal diagnosis basic views …?
Initially, fetal echocardiography included only
a four-chamber view (basic cardiac echocardiographic examination [BCEE]) of the heart, and
outflow tract view (OTV) and
three-vessel trachea view (3VTV)
Indications of fetal echocardiography could be as follows: Fetal—
suspected CHD on screening ultrasonography,
fetal chromosomal anomaly—fetal extracardiac anatomic anomaly,
fetal cardiac arrhythmia - persistent bradycardia or tachycardia, irregular rhythm, and
nonimmune hydrops fetalis
Indications of fetal echocardiography could be as follows: Maternal ..?
maternal metabolic diseases, e.g., overt diabetes, phenylketonuria, systemic lupus erythematosus, maternal exposure to alcohol, and intake of cardiac teratogenic medications
Which abnormalities that may be missed by fetal echocardiography ….?
Coarctation of aorta,
small ventricular and atrial septal defects,
partial anomalous pulmonary venous return, and
mild aortic or pulmonary stenosis
Indication for Cell-free fetal DNA screening for aneuploidy….?
currently is recommended only for women at a high risk for aneuploidy—women who are >35 years old, have a history of a fetus or newborn with aneuploidy, are carriers of a balanced translocation, or have a positive traditional screening test
Fetal cell fraction is a major determinant of a good NIPT—a minimum of what percentage is needed..?
4.5%
possible sources of false-positive results NIPT ..?
Maternal chromosomal abnormalities or
malignancy
vanishing twins or
confined placental mosaicism
Failed NIPT can occur in……?
maternal obesity and very early GA.
chorion villus sampling (CVS)..?
Performed at or after 11 weeks of gestation (till 13+6 weeks),
CVS provides the earliest possible confirmation of a genetically abnormal fetus through analysis of trophoblast cells
CVS, if performed before 10 weeks of gestation, can be associated with an increased risk of which anamoly..?
fetal limb reduction defects and oromandibular malformations
About Diagnostic study - amniocentesis ..?
Amniotic fluid around the fetus is aspirated through a needle guided by ultrasound.
The removed amniotic fluid (~20 mL) is replaced by the fetus rapidly within 24 hours
Amniocentesis can technically be performed as early as…?
10 to 14 weeks of gestation
although early amniocentesis (<13 weeks) is associated with a pregnancy loss rate of 1% to 2% and an increased incidence of clubfoot
Loss of the pregnancy following an ultrasonography-guided second trimester amniocentesis (16 to 20 weeks) is lower..?
at 0.5% to 1.0% in most centers.
Enzymatic/biochemical analysis of amniotic fluid…?
Increased levels of AFP along with the presence of AChE identify NTDs with >98% sensitivity
Assessment of fetal lung maturity by LS ratio (lecithin/sphingomyelin ratio)
percutaneous umbilical blood sampling (PUBS) risk…?
PUBS is associated with a 1% to 2% risk of fetal loss and 5% risk of preterm delivery.
fetal bradycardia, defined as an FHR
<110 bpm
Feral tachycardia, defined as an FHR…?
> 160 bpm
Fetal dysrhythmias are typically associated with FHR……?
> 200 bpm
Normal Baseline variability of FHR ….?
beat to beat by approximately 5 to 25 bpm
Accelerations of the FHR in response to …?
movements
Early decelerations features …?
Early decelerations are symmetric in shape and closely mirror uterine contractions in time of onset, nadir, duration, and termination.
They are benign and maintain good baseline variability
Late decelerations features …?
Late decelerations are decreases in the FHR that occur “late” in relation to uterine contractions. The onset, nadir, and recovery of the deceleration occur after the beginning, peak, and end of the contraction, respectively.
Late decelerations are the result of …..?
uteroplacental insufficiency and possible fetal hypoxia
As the uteroplacental insufficiency/ hypoxia worsens, what happens to decelerations ..?
(i) baseline variability will be reduced and then lost,
(ii) decelerations will last longer,
(iii) they will begin sooner following the onset of a contraction,
(iv) they will take longer to return to baseline, and
(v) the rate to which the fetal heart slows will be lower
Variable decelerations features ……?
vary in their shape and have no specific relationship with contractions.
Usually, they result from fetal umbilical cord compression.
