Week 4 Fetal Assessment Flashcards
What is the Primary objective of prenatal screening and diagnosis?
to detect genetic d/o or abnormalities that could affect the woman, fetus, and newborn
Explain Screening vs Diagonistic testing
- Screening detects or IDs individuals who are at risk for an abnormality or disease to then be diagnosed
- Diagnostics precise test for a given condition
What is the major limitation of screening tests?
risk of false-negative and false-positive
What are the diagnostic testing options?
- Chorionic villus sampling
- Amniocentesis
- Preimplantation genetic diagnosis
What are the three categories of ultrasounds?
- Standard
- Limited
- Specialized
What all can an ultrasound tell you?
-Maternal anatomy (cervix, uterus, adnexa)
-Number of fetuses
-Biometry (fetal measurements, estimate gestational age, fetal weight, whether structures are abnormal or not)
–Survey of fetal anatomy
Fetal presentation
-Presence of fetal cardiac activity
-Placental location
-AF volume
What is a limited ultrasound?
provides information about a specific problem or concern that require further evaluation
What is a specialized ultrasound? When is it indicated?
(usually performed by specially trained staff such as MFM physician)
- Suspected or known fetal structural anomaly (gastroschisis)
- Suspected or known fetal genetic or chromosomal abnormality
- Hx of previous preg with anatomic, genetic, or chromosomal abnormality
- Fetal growth abnormalities
- Maternal-fetal complications that affect the fetus (Rh-sensitization)
Most women have at least one ultrasound during pregnancy. What is its purpose?
To confirm pregnancy and determine EDD
When can fetal genitalia be identified?
by the 12th week
What type of ultrasounds are given during the first trimester?
Transvaginal
What is the purpose of the first trimester ultrasounds?
- Confirm preg, number of fetuses, gestational age
- Determine implantation location and location of maternal anatomy
- ID’s markers such as nuchal transluscency
What is the purpose of second trimester ultrasounds?
- Confirm fetal viability
- Evaluate fetal anatomy, including umbilical cord, vessels, and insertion site
- Determine gestational age
- Assess serial fetal growth
- Evaluate quantity of fluid
- Compare fetal growth and AF in multifetal gestations
- Evaluate four or five markers in a biophysical profile
- Locate the placenta when previa is suspected
- Determine fetal presentation
Why is gestational age determination less accurate after the first trimester?
because the combination of individual growth potential and intrauterine environment causes greater variations among fetuses
What is included in first trimester screening?
- Nuchal Translucency
- Maternal serum plasma protein –A and hCG
An enlarged nuchal translucency is defined as____
-What are the implications of this?
- 3mm or greater or above the 99th percentile
- Asscoiated with tristomy 21 and structural abnormalities like heart defects
hCG level in maternal blood normally ___ every ___ days for the first ___ weeks of pregnancy
-When does hCG peak?
Doubles every 2 days for the first four weeks. Peaks at 8-10 weeks
Increased levels of maternal hCG have been associated with ____ and decreased levels are associated with ____
- Trisomy 21
- Trisomy 13 and 18
What is plasma protein-a (PAPP-A)? Decreased levels in the first trimester are linked to ___
- Glycoprotein made by the placenta and is released directly into the maternal bloodstream
- Trisomy 21
What are some independent first trimester ultrasound markers
- Nasal bone assessment (11-14 weeks)
- Hypoplasia and flat nose
What is Cell-free fetal DNA (cfDNA)?
Small fragments of cfDNA originating from maternal and fetal cell breakdown at the placental level mix freely in maternal circulation
cfDNA screening is used to screen for ___
- Trisomy 21, 18, 13
- Sex chromosome somposition
- Microdeletions and microduplications
What makes cfDNA analysis challenging?
the test can’t distinguish between fetal and maternal DNA leading to false results
can neural tube defects be ID’ed with cfDNA?
No
What is the function of the second trimester multiple marker screening?
Reports a woman’s risk for trisomy 21, 18 and NTD
When is the optimal time to do the second trimester multiple marker screening? What is the full range of this screening?
between 16-18 weeks
-full range is 15-22 6/7
What is included in the second trimester multimarker screening? What is the common characteristic of these hormones/proteins?
-hCG
-Alpha-fetoprotein
-Inhibin A
-Unconjugated estriol (uE3)
These hormones and proteins are produced by the fetus or the placenta and cross over into maternal circulation
What does the triple screen measure?
hCG, AFP, uE3
How is risk calculated in second trimester multimarker screenings?
Computer risk calculations use serum values along with demographic information to calculate risks
What is AFP?
Glycoprotein that is produced early in the first trimester in the yolk sac and eventually from the fetal GI system
Where is AFP produced?
Fetal plasma, then into urine, swallowed and digested
Where can AFP be found?
- AF
- Fetal circulation
- Maternal circulation
AFP levels increase until ___ weeks then they begin to decline
10-14 weeks
Low AFP levels can indicate what three things?
- Trisomies
- Gestational trophoblastic disease
- Normal fetus with an overestimated gestational age or increased maternal weight
Elevated AFP levels are associated with ___
NTD’s
Where is uE3 produced?
Fetal liver and placenta
How levels of uE3 are associated with ___
Trisomy 18, and 21
Inhibin A that is ____ times higher than normal is associated with ___
two
Tri 21
What is an integrated screening?
combines NT measurement and PAPP-A with a quad screen
What does a quad screen measure?
- hCG
- Alpha-fetoprotein
- Inhibin A
- Unconjugated estriol (uE3)
How is the integrated screening done?
two portions done to compare results
Chorionic Villus sampling (CVS) is done during the ___ trimester
first
What is the benefit of CVS?
If allows for more immediate results earlier in preg than other diagnostics
Chorionic Villi contain ___
This is why they are used for diagnostics
chromosomal, metabolic, and genetic material makeup of the fetus
When is a CVS performed? (Weeks)
between weeks 10 and 13
How is a CVS performed?
Can be done transcervical or trans abdominal
-guided by ultrasound
When are CVS results ready?
5-7 days
What is the main aftercare intervention after a CVS?
RhoGAM if the woman is Rh neg
What are the risks/SE’s involved in a CVS?
- Less than 1% preg loss
- Post-procedure spotting for 2 days
What education is given to women after a CVS
- Cramping is normal the day of
- Rest for 24 hours and avoid exercize, heavy lifting, and sex for several days
- Report heavy bleeding, clots, or tissue passage, leaking of AF or a temp above 100.4
What are the common indications of an Amniocentesis?
- ID of genetic, or metabolic abnormalities
- Determine fetal lung maturity
What are the risks of Amniocentesis
loss less than 1%
-Vag spotting or leaking of AF
What are common post-procedure s/s of Amniocentesis
- May complain of cramping
- Low abdo discomfort that can last 24 to 48 hours
- May notice small amount of AF leakage the first day
- Report heavy bleeding, clots, or tissue passage, leaking of AF or a temp above 100.4
When is a Amniocentesis performed?
between 15-20 weeks
-only if adequate AF is present and viable fetal cells are also present
What is the disadvantage of a Amniocentesis?
-results in 10-14 days
What are the primary lab methods for determining Fetal lung maturity using the results of a Amniocentesis?
Using the lecithin-to-sphingomyelin (l/S) ratio and presence of absence of phosphatidylglycerol (PG) and lamellar body counting
When would an Amnio be used to determine Fetal lung maturity?
When no prior prenatal care has been given and the woman is past her first trimester. Determining gestational age could be off by several weeks by this time. assessing FLM will determine a rough est. of age and viability if delivery is needed
What is Lecithin? (Fetal lung maturity)
a phospholipid component of fetal lung fluid and surfactant
What is spingomyelin? (fetal lung maturity)
amniotic membrane lipid with a relatively stable conc in amniotic fluid during the entire pregnancy
When does Lecithin peak? (Fetal lung maturity)
34 to 35 weeks of gestation
By 35 weeks, the L/S ratio should be
2:1
A L/S ratio of ___ or greater indicates adequate fetal lung surfactant and fetal lung maturity
2:1
Another positive indicator of fetal lung maturity is the presence of ____
phosphatidylglycerol (PG)
Before the results of the Amnio are sent off. ____ can offer information about surfactant levels
Visual inspection of the AF for color and particles
Describe what AF should look like at 35-37 weeks
Cloudy with particles of vernix
What is the test to verify fetal lung maturity via visualization of AF?
-Cloudy with vernix particles and cant read newsprint through the tube considered a mature L/S ratio
What is percutaneous umbilical blood sampling performed?
After 18 weeks
Why is the umbilical vein perferred for P umbilical sampling?
It is larger and less likley to cause complications
percutaneous umbilical blood sampling is used to
- obtain fetal chromosomes,
- manage fetal hemolytic dz,
- confirm congenital infections such as CMV
Who should be offered prenatal screening and diagnosis?
All women who want it
What are the 8 maternal indications for antepartum fetal assessments?
- HTN disorders
- Diabetes
- Chronic renal disease
- Cyanotic heart disease
- Thrombophilia
- Antiphospholipid antibody syndrome
- Cholestasis
What are the What are the 7 fetal indications for antepartum fetal assessments?
- Dec. fetal movement
- Growth restriction
- Post term
- Fetal anomalies
- Multi gestation
- AF abnormalities
- PPROM
What are the 7 “other” indications for antepartum fetal assessments?
- Previous still birth
- AMA
- Obesity
- Abnormal serum markers
- Substance abuse
- Poor education
- Black Race
What are the 6 common fetal surveillance (screening) methods?
- Fetal movement counting
- NST
- CST
- Biophysical profile
- Modified Biophysical profile
- Doppler flow study
Decreased fetal movement can indicate___
Hypoxia-decreased movement to conserve O2
How is fetal movement counting done?
- Women are instructed to rest in a quiet location and count distinct fetal movements
- Maternal perception of 10 distinct movements in a 1-to-2 hour period is reflective of a nonhypoxic fetus at that point in time
What is the non stress test? (NST)?
-Measurement of FHR using the EFM
What are some FHR signs of hypoxia?
FHR does not accelerate with movement
What does the non stress test identify?
IDs whether an increase in the FHR occurs when the fetus moves, indicating adequate oxygenation, a healthy neural pathway from the fetal CNS to the fetal heart, and ability of the fetal heart to respond to stimule
FHR accelerations after 32 weeks are ___
-Before?
15X15 less than 2 min
-10x10
Describe the procedure for the non-stress test
- min of 20 min FHR monitoring
- Mom pushes button when she feels fetal movement
- May require fetal stimulation
How is fetal stimulation done?
-Buzzer for 1-2 seconds
Non-reactive NST are defined as ____
fewer than 2 accelerations during a 40-minute period
Vari. decels are associated with _____
-If these occur during a NST, when should interventions be done?
- Umbilical cord compression
- Non recurrent and last less than 30 sec
What does the contraction stress test determine and when is it done?
- Determine fetal well-being in response to stress – contractions
- Done if NST nonreactive
What two things can be used to induce contractions in a contraction stress test?
- Oxytocin
- Nip stim
When is a CST negative?
No late decelerations
When is a CST positive?
late decels are present with a minimum of 50% of the contractions, even when fewer than three contractions occur in 10 minutes
What is a Biophysical profile?
A screening tool that combines EFM with ultrasounds
What does a biophysical profile tell you?
reflection of CNS and provide an indirect means of evaluating fetal oxygenation
What four things does a biophysical profile tell you?
- Fetal movement
- Fetal tone
- Fetal breathing movement
- AF amount
What are the four short term indicators of adequate fetal oxygen in a BPP
FHR reactivity
Fetal breathing movement
Fetal movement
Fetal tone
What is the long term indicator of fetal oxygenation in a BPP
Adequate AF
Place the order of BBP reactions as hypoxemia increases in the fetus
- Loss of FHR reactivity
- Reduced then absent Fetal breating movements
- Reduced then absent gross fetal movements
- Reduced fetal tone
- Reduced amniotic fluid volume if hypoxemia is prolonged
what causes decreased AF during prolonged hypoxemia?
- Blood is shunted to vital organs
- Blood is shunted away from the kidneys
- Less renal perfusion = less urine
- less urine = decreased AF
What is a modified BPP?
a NST plus AF measurements
the NST is a short-term indicator of ____
fetal oxygenation
an AFI greater than ___ is considered reassuring
10
an AFI greater than 18-20 indicates____
Excessive AF (Polyhydramnios)
