OB Module 4: Fetal Surveillance Flashcards
What are the two patients we truly take care of in OB
mother
child
What tests are included under Ante Partum Fetal Surveillance
Fetal Movement Assessment
Nonstress Test
Contract Stress Test
BPP (Biophysical Profile)
Umbilical Artery Doppler Velocimetry (done via ultrasound)
Ultrasound
Amniocentesis
Chorionic Villi Sampling
What are some maternal conditions that may warrant fetal surveillance
Antiphospholipid syndrome
Hyperthyroidism (poorly controlled)
Hemoglobinopathies (hemoglobin SS, Sc, or S-thalassemia)
Cyanotic heart disease
Systemic lupus erythematosus
Chronic renal disease
Type 1 diabetes mellitus
Hypertensive disorders
What are some pregnancy related conditions that may warrant fetal surveillance
Pregnancy-induced hypertension
Decreased fetal movement
Oligohydramnios
Polyhydramnios
Intrauterine growth restriction
Postterm pregnancy
Isoimmunization (moderate to severe)
Fetal anomalies
Previous fetal demise (unexplained or recurrent risk)
Multiple gestation (especially with significant growth discrepancy)
Oligohydramnios
Low amount of amniotic fluid
Polyhydramnios
High amount of amniotic fluid
Isoimmunization
rH incompatabilities
What test is the lowest level of fetal surveillance
Fetal Movement Assessment
AKA: Fetal Kick Counts
What is done in a Fetal Movement Assessment
the mother counts the fetal “kicks” as a means of antepartum fetal surveillance
When should a fetal kick count be done
after dinner with the mother resting on her side ideally
it is done for up to 2 hours then or anytime the baby tends to kick
A mother should not do what within 2 hours prior to a fetal movement assessment
smoke d/t diminished oxygen flow
What are the ideal results for a fetal movement assessment
She should have at least 10 movements in a 2 hour period
if she feels that before 2 hours are up she is done and set to go
What is important to keep in mind about the timeline of a fetal movement assessment
infants can sleep up to 45 minutes so that may be why there is no kicking
Advantages of the Fetal movement assessment
low tech
done as a daily assessment
can be done on all pregnancies
reassuring for the mother
Major disadvantage of the fetal movement assessment?
it is done at a very busy time of day
What are some methods of electronic fetal monitoring?
External monitoring
internal fetal monitoring
IUPC - intrauterine pressure catheter
What is the basic way electronic fetal monitoring works
Two belts go on mother
top one monitors contractions - toco transducer- detects tone in the abdomen that detects contraction (it is on top since the contraction pulls up)
the lower one detects fetal heart tones assuming the baby is in a normal spot
the lowest are optimal anterior
How does an internal fetal monitor to check the scalp work?
to get the internal monitor in the cervix must be dilated, membranes ruptured, and you need to be able to palpate the bony prominences of the infant (not placing it on the fontanelle or something else)
What are the three important parts of EFM (electronic fetal monitoring) interpretation>
- Baseline (For FHR)
- Variability (Jaggedness to Lines)
- Periodic Changes (Increases and Decreases)
How are FHR electronic monitoring results categorized?
It is a three tier system with 3 categories
Category I - Normal
Category II - Suspicious
Category III - Ominous
EFM: Variability
reflects the health of the nervous system, chemoreceptors, baroreceptors, and cardiac responsiveness
What is Variability indicative of in EFM
the health of the parasympathetic nervous system (is it intact, oxygenated, functional) if it is 5-10 bpm above baseline
the health of the sympathetic nervous system if it is 10-25 bpm off the baseline
How many BPM off the baseline of a FHR is indicative of the health of the PNS
5 to 10 bpm
How many BPM off the baseline of an FHR is indicative of the health of the SNS
10 to 25 bpm
What is acceleration of the EFM
an increase in amplitude of 10-25 bpm off the baseline indicative of the health of the SNS
should only occur once in a while
What does the fetal heart rate snapshot about a child?
how they are doing and what is happening neurologically
What does prematurity do to EFM variability
it decreases variability so there will be little rate fluctuation before 28 weeks!
When should variability in EFM be present
after 32 weeks
What, other than prematurity can decrease EFM variability
fetal hypoxia
congenital heart anomalies
fetal tachycardia
systemic pain medications - temporarily
fetal metabolic acidosis
CNS depressants
fetal sleep cycles
preexisting neurological abnormalities
betamethasone
Why is there little fluctuation in FHR/EFM before 28 weeks
because the neurological system must be developed enough to allow and spot changes
What are the variability changes (amplitude/BPM) in EFM for the following:
Absent
Minimal
Moderate
Marked
Absent - amplitude range undetectable
Minimal = <5 BPM
Moderate - 6-25 BPM
Marked- >25 BPM
What appears to be the most significant intrapartum sign of fetal compromise?
Persistently minimal or absent FHR variability
While persistently low variability is an ominous sign…
the presence of good FHR variability may not always be predictive of a good outcome
Betamethasone
a drug given to accelerate infant lung maturity
can decrease EFM variability though
What is important to keep in line about looking at the variability of a monitor?
it is always slightly exaggerated so with something like absence it is even worse than it appears!
What may cause some temporary drops and declines in variability?
movement where the babies heart rate is outside the detection of the monitor
What is the normal baseline for FHR
120-160 BPM
Often this is on the high end for prematurity
they tend to be within 140-160 or 130-250 area
Fetal bradycardia
baseline HR <120 BPM
If 100-120 BPM with normal variability it is not associated with fetal acidosis
What are some etiologies for Fetal bradycardia
heart block (if little or no variability)
occiput posterior or transverse position
serious fetal compromise
if the neurological system is maturing and the baby goes post date then it is common to go low as well
Why does a premature baby tend to have a faster heart beat
because the neurological and cardiac systems are less mature and not coming down as easy
Fetal Tachycardia
fetal baseline HR >160 BPM
Fetal Tachycardia is considered a ___ pattern
nonreassuring (ominous)
When is Fetal Tachycardia considered mild? severe?
Between 160-180 BPM for mild; >180 BPM for severe
Why might a fetus have a HR of >200 BPM?
it is usually fetal tachycardia due to fetal tachyarrhythmia or a congenital anomaly rather than hypoxia
Persistent Fetal Tachycardia
a consistent >180 BPM HR that often occurs in conjunction with fetal hypoxia, fetal anemia, and maternal fever
What does persistent fetal tachycardia with fetal hypoxia, fetal anemia, or maternal fever suggest?
Chorioamnionitis - infection of the uterus
May have occurred if the cervix dilated and bacteria went up
Category I Fetal heart Rate Tracing
“Normal” FHR Showing All of the Following:
Baseline FHR 110-160 BPM
Moderate Variability
Accelerations Present or Absent
No Late or Variable Decelerations
May Have Early Decelerations
What is a Category I Tracing predictive of?
Normal Acid Base Status at the time of observation and typical routine care to be done
Category II Fetal Heart Rate Tracing
A FHR tracing showing any of the following: (Drops in baseline and variability changes)
Tachycardia
Bradycardia w/out Absent Variability
Minimal Variability
Absent Variability w/out Recurrent Decelerations
Marked Variability
Absence of Accelerations After Stimulation
Recurrent Variable Decelerations w/ Min/Mod Varia.
Prolonged Decelerations >= 2 min but less than 10min
Recurrent :ate Decelerations w/ Moderate Variability
Variable Decelerations w/ Other Characteristics such as slow return to baseline and “overshoot”
What is Category II FHR Tracings NOT Predictive of?
Abnormal Fetal Acid Base Status
BUT it does require continued surveillance and reevaluation
Category III FHR Tracing
Fetal Heart Tracing Showing EITHER of the following:
- Sinusoidal Pattern
OR
- Absent Variability w/ Recurrent Late Decelerations, Recurrent Variable Decelerations, or Bradycardia
What is Category III FHR Tracings Predictive Of?
Abnormal fetal Acid base status at the time of observation
Depending on the clinical situation, efforts to expeditiously resolve the underlying cause of the abnormal FHR should be made - such as rapid induced delivery
Sinusoidal Pattern
an abnormal category III FHR pattern
also called “Saw Tooth” pattern with it very equal going up and down
indicative of fetal hypoxia from anemia or O2 disruption
Periodic FHR tracing changes include both __ and __
accelerations and decelerations
What sort of pattern do we want to see on an FHR tracing, and what could hypothetically sometimes happen?
We want to see baseline range with some jaggedness that changes giving variability - hopefully that variability is an acceleration in HR
Sometimes we get decelerations but we must consider what they occur in relation to - if a contraction just occurred then we know some squeezing temporarily cut off O2 and would lead to that
Decelerations on FHR Tracings are Classified as…
Early
Variable
Late
Prolonged
Early Decelerations are due to …
head compression
Early and Late Decelerations tend to have what shape
A Subtle U shape
Variable Decelerations tend to have what shape
A Very Deep V or W shape
Why is head compression so important to know about with FHR tracings?
Head compression is a mirror image of contraction rate and depending on compression severity or duration we may lose variability gradually if the baby cannot make it thought
We may see this coming as the head makes it through the ischial spine region
Why are late decelerations in FHR so concerning
they are an ominous sign of placental insufficiency (inadequate blood flow)
as the uterus contracts, placental blood flow will cut off and if the placenta is already compromised there is even worse blood flow compromise
How can induction of labor cause late decelerations in FHR?
Never sure how responsive the uterus will be so we can cause severe and strong contractions without much of a rest period in between
When occurring progressively less blood flow will get to the baby and cause late decelerations
When will late decelerations begin and end in reference to contraction?
It will start toward the peak of contraction and will recover at the end of a contraction
What causes variable deceleration
Cord Compression - and depending on where the cord is this may or may not occur with contractions
When will variable decelerations correspond with contractions?
If the cord is around the shoulder or neck
OR
With specific maternal positions that move the cord
Why can variable decelerations be very significant or intermittent?
90% of women will have variable decelerations in the second stage as the baby comes down the vaginal vault because of cord pinching - recovery and potential for overshoot should be looked for however
Reassuring Pattern of FHR
Baseline FHR 120-160 BPM
Preserved FHR beat to beat and there is long term variability
Accelerations last for 15 or more seconds above baseline and peak at 15 or more BPM
Saltatory Pattern of FHR
Wide and more marked variability
The oscillations of FHR are above and below the baseline exceeding 25 BPM
It is all over the place and the bottom graph (contractions) will have a bell curve shape at times of contraction
Early deceleration is associated with …
head compression
Early Decelerations are described as “Mirror Image,” Why?
The onset and return of the deceleration coincide with the start and the end of the contraction giving this characteristics subtle U shape that repeats
If there is a low variability and early decelerations what may that mean?
the baby may have been in labor for a long time and is losing some reserve
Late Decelerations are caused by …
reduced placental exchange
What are some examples of reduced placental exchange causing late decelerations
excessive uterine contractions
maternal hypotension (maybe due to a sedative)
maternal hypoxemia
hypertensive disorders
diabetes
IUGR
abruption
COVID-19 resp effect and Hgb effect causing maternal hypoxemia
Anything that can affect the health of the placenta
Late decelerations are ___ shaped and occur when?
U shaped and occur late in contraction toward the peak of one (when O2 is cut off)
So as the contraction hits the top of the bell curve shape that’s when early deceleration would occur - a late deceleration occurs as it returns toward the contraction line baseline and ends after the contraction is done for a bit
What is a late deceleration with loss of variability indicative of?
ominous pattern
reflects uteroplacental insufficiency and immediate delivery is needed (C Section ASAP)
Variable deceleration is associated with …
umbilical cord compression with pre and post accelerations (“Shoulders”) that occur before and after the contraction
What shape is a variable deceleration
V or W shaped and reaches its nadir in 30 seconds
Nadir
lowest point
___% of women have variable decelerations in the second stage of labor
90
What does a severe variable deceleration with overshoot say?
With variability preserved this represents and acute episode in a fetus with good reserve
these are longer decelerations that are slower to return to baseline that also overshoot (overcompensate)
If a first time mom we may need to consider C Section
Overshoot
overcompensation of deceleration indicating hypoxia in a newborn
If a distress pattern does not cease, vaginal birth is not imminent, bradycardia (<120) is present, non-average variability is present/absent and things are not reassuring indicates what?
C Section
If the bradycardia is present without vaginal birth imminent and the distress pattern will not cease with intervention = C Section
If variability is not average and it is not reassuring with the other things then it also = C Section
Fetal Distress = C Section Delivery
Nursing Interventions for Fetal Distress to try and prevent need for C section`
Reposition the patient
turn off pitocin
increase IV rate
administer O2
assess labor progress/scalp stimulation
assess for cord prolapse
notify provider
prepare for delivery and resuscitation (right there - sterile field, etc)
How can position change help with fetal distress
sometimes it helps the baby rotate to correct head compression
it can also optimize blood flow to placenta or ge the baby off the cord
Why stop Pitocin with fetal distress
it induces contractions which will worsen fetal blood flow`
How much O2 is administered in Fetal Distress
8-10 L O2 via non rebreather in order to max saturate Hgb
Scalp Stimulation
Noogie-ing the baby through the cervix with a finger to see if there if fetal response recovery
Non Stress Test
period of electronic fetal monitoring done IN THE ABSENCE OF CONTRACTIONS
done before labor to see how the baby will deal with the main stressor (contractions) of labor and everyday life without contractions present
non invasive
How should the FHR change with fetal movement in a non stress test
it should temporarily accelerate with fetal movement
Heart Rate Reactivity in a non stress test is believed to be a good indicator of what?
normal fetal autonomic function
What is loss of reactivity commonly associated with during a non stress test? What are some abnormal uncommon associations?
Commonly its due to a fetal sleep cycle
It can occur from any cause of CNS depression including fetal acidosis which is concerning
What are the results we wish to see during a fetal non stress test
Accelerations, a stable baseline, absence of recurrent/massive decelerations and some variability
__ Accelerations within ___ minutes lasting at least ___ seconds and at least ___ BPM ___ baseline is the ideal non stress test result
2 accelerations within 20 minutes lasting at least 15 seconds and at least 15 BPM Above Baseline
Why is a non stress test not done in pre term babies?
Not done d/t a lack of neurological variability
Barring anything abrupt, the non stress test is usually indicative of a baby that will stay good..
for at least 48 hours (2 days)
What is a reason relating the placenta that it may be important to do a non stress test 2-3 times a week?
Placenta is supposed to last 40 weeks but it can degrade early from different things - so if we monitor pregnancies we can continue to watch for needed interventions and compromises early
Results of a nonstress test are classified as __ or __
reactive or nonreactive
What is a reactive result of a nonstress test
If there are 2+ fetal heart rate accelerations of 15 beats for 15 seconds within a 20 minute period, with or without fetal movement perceived
What is a nonreactive result of a nonstress test
one that lacks sufficient fetal heart rate accelerations over a test 40-minute period
the bottom graph may have a spike of fetal movement but there are no accelerations in the top graph (FHR)
“Non Reactive to Fetal Movement”
In a FHR tracing, what does the top graph show and what does the bottom graph show?
Top is the FHR
Bottom shows uterine activity (a spike would indicate fetal movement or contraction - corresponds with an increase in the top graph)
What to do next if there is a nonreactive nonstress test result?
extend 30 minutes - if there is another nonreactive result extend another 30 minutes - if non reactive again then you do diagnostic ultrasound and CST or BPP or induced delivery
What to do if there is a nonreactive result with no accelerations and spontaneous decelerations?
diagnostic ultrasound and CST or BPP or induced delivery
After an initial non reactive nonstress test result what may be asked of the mother?
Did they smoke within the last 2 hours
When did she last eat and what did she have (baby needs calories) - she may be given cold fruit juice to stimulate the fundus and baby
Stimulation of the baby like rubbing abdomen//bumping head between fingers/talk loud to wake baby and have it respond
In a worst case scenario you may need to do acoustic stimulation, what is this?
Vibratory stimulation after a non reactive nonstress test result
it is put over the fetal head and set off for only 3 seconds to aggressively stimulate the baby
Why may we do a contraction stress test after non reactive nonstress test results?
to check the baby for reactions to diminished blood flow
BPP may tell us what after nonreactive nonstress test results
indicators of wellbeing
Contraction Stress Test
involves assessment of the FHR on electronic fetal monitoring in response to uterine contractions that are induced
contractions (3 of them) are made over 10 minutes and we monitor for responsiveness
If the baby is not well oxygenated (non reactive), what will occur during a contraction stress test?
uterine contractions with transiently WORSEN the fetal condition
result will be a fetal Heart rate pattern of late decelerations
What may uterine contractions provoke or accentuate?
accentuate a pattern a variable decelerations caused by fetal umbilical cord comrpession
If we create a situation with a contraction stress test with 3 contractions and a baby cannot handle that with FHR changes, then that means what?
they have a low survival chance of surviving hours of contractions in L&D
Relative contraindications to the contraction stress test
Things that are associated with an increased risk of preterm L&D, uterine rupture, or uterine bleeding including:
Preterm labor or certain patients at high risk for preterm labor
preterm membrane rupture
history of extensive uterine surgery or classic C section
known placenta previa (across the cervix)
Contraction stress test is interpreted by the presence of absence of…
late fetal heart rate decelerations - which are defined as decelerations that reach their nadir after the peak of contraction and that usually persist beyond the end of the contraction
What are the result categories of the contractions stress test
Negative
Positive
Equivocal Suspicious
Equivocal Hyperstimulatory
Unsatisfactory
Negative Contraction Stress Test
No late or significant variable decelerations
In the test “negative” is a good thing
Positive Contraction Stress Test
Late decelerations following 50% or more of contractions (even if the contraction is frequency is fewer than 3 in 10 minutes)
Ominous signs may mean quit early before 10 minutes or 3 contractions
Equivocal-suspicious Contraction Stress test
intermittent late decelerations or significant variable decelerations
this may be less than following 50% of contractions - or more
Equivocal Hyperstimulatory Contraction Stress Test
FHR decelerations that occur in the presence of contractions that are more frequent than every 2 minutes or last longer than 90 seconds
Unsatisfactory Contraction Stress Tests
Fewer than 3 contractions in 10 minutes or a tracing that is not interpretable
may look ominous but we caused it - may be creating a situation of prolonged or too frequent compression of blood vessels
Umbilical Artery Doppler Velocimetry (UADV) (Doppler Blood Flow Studies)
Doppler ultrasonography is used to assess the umbilical artery blood flow
Done antepartum
Checks quality of blood flow going to the fetus - and it shows a ratio of how much systolic to diastolic pressure we should be seeing
What is UADV believed to show?
it is believed that flow velocity waveforms in the umbilical artery of fetuses with normal growth differ from those of fetuses with growth restriction - ex: diminished growth or circulatory issues
With extreme intrauterine growth restrictions how may umbilical artery flow (UADV)) differ and what may this be associated with
the flow may be low, absent or even reversed
this is associated with a high perinatal mortality rate among such pregnancies
With utero-placental blood flow as the mom’s heart beats …
more pressure is pushed in, but even between heart beats (rest) we should still see blood flowing through the cord to the baby
Advantages of Doppler Blood Flow Studies
Non invasive
Can be scheduled at regular intervals for women at risk
measures blood flow changes in maternal and fetal circulation
allows for assessment of placental function
done regardless of whether mom and baby are at risk or not
With a doppler blood flow study what result do we look at
Systolic:Diastolic Ratio
A doppler flow study can be initiated at __ to __ weeks
16 to 18 weeks
What is a Normal doppler flow study result at 26 weeks? At term? What is high and shows an increase in placental bed resistance?
26 Weeks: 2.6
term - 3
High - 5
The basic thing to know about doppler blood flow study results is …
we look at blood flow through the cord and monitor for changes in that that can help us evaluate risk for pregnancies and change
What are some reasons Ultrasound is used in pregnancy
Confirm Pregnancy and Fetal Position
Evaluate FHR and Fetal Respiration
Identification of more than one embryo or fetus
For examination of anatomical fetal structures (NT) -
Estimated gestational age, fetal weight, fetal growth
Location of the placenta and amniotic fluid volume
Accompanying invasive procedures (ex: amniocentesis)
to determine placental grading
detection of fetal death
When are structures checked first for via ultrasounds?
18-20 weeks when large and shaped enough
Serial Ultrasound Benefit
You can watch fetal growth overtime
What is the rule regarding estimated gestational age via ultrasound
the earlier you can get one done the better
Benefits of Ultrasound
can assess the fetus over a period of time, allowing midwives or physicians to study the gestation serially
Noninvasive and painless
non radiating to both the woman and her fetus
it has no known harmful effects
the nurse provides an opportunity for the woman to ask questions
the nurse can act as an advocate at this time
done on an unborn baby
can assess a baby over time when done serially
Ultrasound scanning permits…
visualization of the fetus in utero
Standard ultrasound visual of something like the face does not…
does not have sharp imagery to
What is the known safety regarding 3D and 4D ultrasounds>
they are newer and use different levels of ultrasounds so there is greater ultrasound wave exposure but it is unknown how unsafe or safe this is
What is 3D and 4D ultrasound for?
not just visualizing the baby, it is to determine physical abnormalities and the location of the cord
Biophysical Profile (BPP)
Consists of non-stress test and 4 observations made via real time ultrasonography
checks fetal wellbeing
What 4 things are observed in the BPP
Fetal Breathing Movements
Fetal Movement
Fetal Tone
Determination of the Amniotic Fluid Volume
How should breathing be in a BPP
intermittent, not continuous
How should fetal tone be in a BPP
flexed
How are the 4 observations scored in BPP
either as 2 points (normal or present) or 0 points (abnormal, absent, insufficient) - no partial points
What do we see with amniotic fluid in a BPP? What is unique about this though?
We do not get an estimate of amount of fluid, we just want to see if there is a single cm pocket of amniotic fluid
diminished amniotic fluid could exist but it still would get the full 2 points
What does a composite BPP score of 8 or 10 mean
normal results
What does a composite BPP score of 6 mean
equivocal
What does a composite BPP score of 4 or less mean
abnormal
What will warrant further evaluation regardless of composite BPP score
Oligohydramnios (lower than normal amniotic fluid levels)
the amniotic fluid tells us the health of the placenta but also wellness of the baby since it drinks and excretes it
Amniocentesis
Invasive needle procedure into the uterine cavity to obtain amniotic fluid
Allows us to test the amniotic fluid and provide genetic information about genetic disorders early in pregnancy or if done late in pregnancy to check fetal health or lung maturity
Amniocentesis can screen for what genetic issues?
Down Syndrome (Trisomy 21) d
Trisomy 18 and neural tube defects (NTDs)
Can provide information about fetal lung maturity
Amniocentesis helps..
to evaluate fetal health
What needs to be done concurrently when doing an amniocentesis?
- Very good sterile technique
- Ultrasound in order to find fetal structures and where there is a pocket away of amniotic fluid - put the needle in carefully at a depth and take some fluid without hitting the baby
The Triple Test and Quadruple Screen
Amniotic Fluid Analysis
Measures substances in the amniotic fluid and information can help identify fetal anomalies
Can allow growing cells and study chromosomes - takes several days
Can allow us to see lung maturity
Fetal Lung Maturity is determined by what 3 things
- Lecithin/Spingomyelin Ratio
- Presence of Phosphatidylglycerol
- Level of Lamellar Body Counts
Lecithin
A surfactant
How does the amount of amniotic fluid available in the womb change lecithin levels?
A high amount of fluid can give false low lecithin levels
A low amount of fluid can give erroneously high lecithin
How do we account for how amniotic fluid changes levels of lecithin falsely
we use a constant - sphingomyelin
Sphingomyelin
a substance released from skin cells
we use it to take away the variability potential of amniotic fluid on lecithin
Phosphatidylglycerol
An indicator of fetal lung maturity
When is a Phosphatidylglycerol level test done?
We do Lecithin:Sphingomyelin ratio first since it is inexpensive and faster
If the lungs are on the cusp of being immature, we order PG levels but they are more expensive and lab intensive
What Licithin:Sphingomyelin ratio indicates for us to look at Phosphatidylglycerol levels?
If the ratio is less than the normal 2:1 L:S
When are fetal lung maturity indicator tests like L:S ratio and PG levels warranted and why?
For at risk pregnancies where we may need to do a C section or induce labor because damage could occur to mom or baby
We do these to test if the babies lungs are mature enough incase we must
Chorionic Villus Sampling
Invasive/catheter procedure done transabdominally or transcervically between weeks 10-12 for first trimester diagnostic studies
takes some placental tissue
Advantages of Chorionic Villus Sampling
Allows for early detection of fetal disorders
Short waiting time for results compared to other tests
Disadvantages and Risks of Chorionic Villus Sampling
Increased risk of injury to fetus
Inability to detect neural tube defects
Potential for repeated invasive procedures
Risk for failure to obtain placental tissue
Risk of contamination of specimen
risk of leakage of amniotic fluid
Risk for intrauterine infection
Risk for Rh alloimmunization (if mom is Rh- and baby is + and accidentally introduced)
Harmony and Maternit21 are better tests in some cases
Harmony and Maternit 21 Tests
Mother blood tests that can screen for some of the defects looked for in chorionic villus sampling
can end up being preferable as it is less invasive
