Chapter 15: Prenatal Diagnostic Tests Flashcards
After the transcervical chorionic sampling, the nurse should check maternal ________________ and fetal _______________. The mother should ______ for several hours.
vital signs, heart rate, rest
A positive CST test indicates a possibility of ______________ of labor, which would indicate a _____________
intolerance, C section
Maternal assessment of fetal movement or “kick counts” should have at least ___ fetal movements within ___ hours
10, 12
Increased AFP levels are associated with this
neural tube defects
To encourage the fetus to stay awake during the NST, give the mother this
Food and/or drink
Accuracy of ultrasounds can be limited with maternal __________.
obesity
Three other markers that are often assessed with alpha-fetoprotein (AFP) screening
hCG
estriol
inhibin A
(This is also known as the Triple Screen)
The Percutaneous Umbilical Blood Sampling (PUBS) procedure is used to detect these four things
- blood disorders
- acid-base imbalance
- infection
- fetal genetic disease
A straight line on an NST indicates this
no variability
two indications or purposes for third trimester amniocentesis
- hemolytic disease
- determine lung maturity
Maternal assessment of fetal movements begins at ___ weeks
28
If the pregnant woman has diabetes, the LS ratio (does, does not) ensure fetal lung maturity. Amniotic fluid is further tested for the presence of these two phospholipids
does not
phosphatidylglycerol (PG)
phosphatidylinositol (PI)
Before 32 weeks, a reactive NST shows ___ FHR accelerations within ____ minutes in which each acceleration is ____ beats above the baseline for ___ seconds
2, 20, 10, 10
A nipple stimulation test involves brushing the palm across one nipple for __ minutes, stopping if a contraction begins. If contractions do not start after this time period, then test is repeated after ___ minutes of rest.
2, 5
Five main uses of an ultrasound during pregnancy
- presence and location of pregnancy
- multifetal gestation
- gestational age
- viability confirmation
- aids in performance of other tests
This size needle is used for an amniocentesis procedure
3-4 inches
20 or 21 gauge
Each parameter on a biophysical profile can get __-__ points, making a total of ___ points maximum possible with at least __ being a good result.
0, 2, 10, 8
How much amniotic fluid is removed for analysis during an amniocentesis?
20 mL
No change or increases in HR with contractions indicates a (positive, negative) CST
negative
If hCG is increased, then estriol is (increased, decreased)
decreased
Two things that can interfere with the mother’s ability to feel fetal movements
anterior placenta, maternal drugs
Drops in HR with contractions at least ___% of the time indicate a (positive, negative) CST
50, positive
After 32 weeks, a reactive NST shows ___ FHR accelerations within ____ minutes in which each acceleration is ____ beats above the baseline for ___ seconds
2, 20, 15, 15
This type of ultrasound is used in the first trimester and why
transvaginal
uterus, gestational sac, ovaries, and fallopian tubes are deep in pelvis
Moderate (goal) variability in an NST is between __-__ bpm
5, 25
Indications for second trimester amniocentesis:
1. maternal age _______________
2. chromosomal abnormality in ________________________
3. sex determination for maternal carrier of ____________________
4. birth of previous infant with one of these three things
5. pregnancy after multiple ____________________________.
6. unexplained elevation of maternal serum ______
7. maternal Rh ___________________
- 35 years or older
- close family member
- X-linked disorder
- chromosomal abnormalities, neural tube defect, body wall defect
- spontaneous abortions
- AFP
- sensitization
Alpha-fetoprotein (AFP) screening is performed to identify these two things
open body wall defects
chromosomal anomalies
A doppler ultrasound is used in complicated pregnancies with placental insufficiency to assess ____________ and ___________ in the umbilical cord.
blood flow, pulsation
Advantages of amniocentesis
Simple, safe, painless with few reported complications
Four risks associated with transcervical chorionic sampling
- pregnancy loss
- limb defects (before 10 weeks)
- uterine infection
- Rh sensitization
Three reasons that prenatal diagnostic tests are done
- detect congenital anomalies
- high-risk pregnancy to evaluate fetal condition
- baseline information
First method used to initiate uterine contractions for a CST if no contractions are present
nipple stimulation test
FHR accelerations (periodic changes) in an NST are ___ bpm above the baseline
15
Marked variability in an NST is >___ bpm, and a baseline cannot be found
25
The mother should count fetal movements __-__ times per day to identify whether the fetus has at least ___ movements in ___ minutes
2, 3, 3, 60
In order to interpret a CST, must have __ contractions that last ___ seconds within ___ minutes.
3, 40, 10
The main protein in fetal plasma that can be measured in maternal blood or amniotic fluid
alpha-fetoprotein (AFP)
A transcervical chorionic sampling procedure is done early in case of this
chromosomal abnormalities incompatible with life (mother may choose to terminate pregnancy)
Medication that is given for a Contraction Stress Test
Pitocin (oxytocin)
This test involves a vibrating device placed on the belly that causes the fetus to move from vibration and sound and thereby increase HR
vibroacoustic test
This test is used to determine how the fetal heart responds to uterine contractions that temporarily decrease placental blood flow
Contraction Stress Test (CST) (or Oxytocin Challenge Test)
Steroid that can be given to help with lung maturity of the fetus
betamethasone
Alpha-fetoprotein screening (screens for, confirms) abnormalities
screens for (does not confirm)
Inhibin A helps detect this chromosomal abnormality and is accurate in mothers of this age group
Trisomy 21, <35
If the nipple stimulation test does not work, this method to initiate uterine contractions for a CST is used
IV low-dose oxytocin
For the amniocentesis procedure, the ultrasound is used for these three things
- locate fetus/placenta
- identify largest pockets of amniotic fluid that can be safely sampled
- guide needle insertion
Fetal viability is determined via ultrasound by observation of the fetal _____________ of at least ______ in length
heartbeat, 5 mm
Three body measurements that help estimate gestational age, especially during last half of pregnancy
biparietal diameter (head circumference)
femur length
abdominal circumference
Decreased AFP levels are associated with this
chromosomal abnormalities (Trisomy 21)
Before amniocentesis, these two baseline levels are collected
maternal BP
fetal HR (FHR)
Disadvantage of amniocentesis
2+ weeks for results; may hinder decision for termination of pregnancy
Normal fetal HR
110-160
Increased detection of hCG increases the possibility of these two chromosomal abnormalities
Trisomy 18, Trisomy 21
After an amniocentesis, the pregnant woman should avoid strenuous activity but resume normal activities after ___________.
24 hours
To be most accurate, AFP screening must be done at ___-___ weeks
16, 18
Chorionic villus sampling provides information about these two things
chromosomal defects
metabolic abnormalities
True gestational age must be known in these two scenarios
- screening for maternal serum AFP (levels change with fetal age)
- intrauterine growth restrictions
The biophysical profile includes these five parameters
- NST
- fetal breathing movements
- gross fetal movements (large trunk movements)
- fetal tone (fine body movements)
- amniotic fluid volume
An ultrasound can detect any fetal defects other than this
inborn errors of metabolism
A non stress test cannot be performed before ___ weeks
28
amniocentesis: lecithin/sphingomyelin (LS) ratio is usually ____ until 30 weeks. The goal ratio is greater than _____. This ratio is the best-known test for estimating ___________________.
1:1, 2:1, fetal lung maturity
Reason why a full bladder may be necessary for better visibility of uterus/fetus in ultrasound
Displaces intestines and elevates uterus
Four contraindications of a Contraction Stress Test (CST)
- placenta previa
- too preterm
- classic uterine incision
- breech presentation
A nonreactive NST lacks the characteristics of a reactive NST within ___ minutes
40
Non stress test (NST): FHR accelerations with movement indicate these two things
- adequate oxygenation
- intact neural pathway from CNS
Most reliable indicator of gestational age in the first trimester
measurement of crown-rump length of embryo
Minimal variability in an NST is between __-__ bpm and usually indicates that the fetus is _________.
2, 4, asleep
This procedure involves the aspiration of fetal blood from the umbilical cord near the placenta for prenatal diagnosis or therapy
Percutaneous Umbilical Blood Sampling (PUBS)
Why is the first 1-2 mL of amniotic fluid discarded during an amniocentesis?
Avoids contamination with maternal cells
Percutaneous Umbilical Blood Sampling (PUBS) procedure risks (4)
infection, fetal loss, cord hematoma, cord laceration
Procedure in which a sample of chorionic villi is obtained by going in through the cervix
transcervical chorionic sampling
To prepare for amniocentesis procedure, pregnant woman placed in this position
supine with pillow/towel under one buttock
After an amniocentesis, the fetus is monitored for (time period) to identify any presence of these two things
30-60 minutes, continuing uterine contractions, nonreassuring fetal heart activity
Percutaneous Umbilical Blood Sampling (PUBS) procedure (3 steps)
- Ultrasound locates placenta, fetus, cord
- Needle inserted through abdomen and uterine cavity into umbilical cord where it meets placenta
- Umbilical vein is targeted for blood aspiration
This type of ultrasound is performed in the second trimester when risk factors are present
comprehensive
After an amniocentesis procedure, the pregnant woman should report any of these four things if they occur
- persistent uterine contractions
- vaginal bleeding
- leakage of amniotic fluid
- fever
Chorionic villus sampling can be performed as early as ____ weeks gestation
10
Amniocentesis increases the risk for these two things
Rh sensitization, fetal loss
Four nurse roles during an amniocentesis procedure
- Acquire supplies
- Prepare room
- Administer terbutaline to quiet contractions; RhoGAM if necessary
- Monitor for complications