1.03 Antepartum Fetal Surveillance Flashcards by Marianne Gwyneth Monsalud

Primary goal of Fetal Surveillance

Prevent Intrauterine Fetal Death

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What happens before IUFD?

fetal acidosis and hypoxemia

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Summary of steps leading to IUFD

Fetal acidosis and fetal hypoxemia > amniotic fluid, fetal movement, and fetal heart rate changes > IUFD > still birth

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Clinical Assessment methods for fetal surveillance

Determination of fetal age
Fundic Height
Fetal Heart Tones

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Once the fetal pole can be visualized, this is the most accurate method for dating the pregnancy

Crown-Rump Length

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The fundic height in cm is equal to AOG in these weeks

20-32 weeks with a margin of +/-2

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Ways to calculate fetal age

LNMP
Fundic Height
Ultrasound Measurement

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T/F: Fetal heart tones can be heard at 8 weeks

Normal range of heart sounds:

F- 12-13

120-170 bpm

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T/F: Fetal death within one week of a normal test is common

F- rare

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T/F: Fetal movements commence as early as 7 days

At what week/s does the fetus start to become organized and start to show rest-activity cycles?

F- 7 weeks

20-30 weeks AOG - reflective of CNS development and maturation

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At what behavioral state is a fetus in when they are at quiet sleep?

State 1F

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At what behavioral state is a fetus in when they have continuous eye movements, absence of body movements, and minimal variability of heart rate

Stage 3F

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At what behavioral state is a fetus in when they have vigorous body movement with continuous eye movement and heart rate accelerations

State 4F (awake)

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T/F: Contraction stress test assesses uteroplacental function that is done in early pregnancy

F- latter part of pregnancy

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At what behavioral state is a fetus in when they have continuous eye movements, gross body movements, and increased variability of heart rate

State 2F (REM SLEEP)

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State if these (increases/decreases) fetal movement

Maternal smoking
Steroid administration up to 72 hours
Glucose load
Sedatives
Fetal positioning (anterior spine)

Maternal smoking - decreased
Steroid administration up to 72 hours - decreased
Glucose load - increased
Sedatives - decreased
Fetal positioning (anterior spine) - decreased

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What must be done to evaluate decreased fetal movement?

Non-stress test and amniotic fluid volume

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T/F: reduced/absent movement is a sign of impending fetal death

The mother must start to monitor fetal movement starting at what week/s?

How many kicks must be felt?

T
Starting 26-28 weeks

at least 10 kicks in 2 hrs and mother’s subjective impression

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How does contraction test work?

T/F: The CST can only be done in a double set up

The baby is intentionally stressed through contractions by:

Mom’s given contractions via nipple stimulation OR Oxytocin therapy (10 units titrated at 6mU/min > at least 3 contractions lasting 40s or longer is needed in a 10 min span > there is brief periods of impaired oxygen exchange > a normal healthy fetus can cope up to 1 minute oxygen impairment while unhealthy fetuses cant

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This is the most important predictor of adequate fetal oxygenation

Variability

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When is acceleration considered?
When is deceleration considered?

T/F: Decelerations are compensatory mechanisms for decreased oxygen

If there is an abrupt increase of bHR of >15 bpm for >15 seconds >32 weeks

If there is an abrupt decrease of bHR of >15 bpm for >15 seconds if >32 weeks

If <32 weeks, change of 10bpm within >10 seconds

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Identify the type of variability

6-25 bpm
>25 bpm
1-5 bpm
0 bpm

Which among the types of variability indicate presence of accelerations? No apparent baseline?

6-25 bpm = moderate
>25 bpm = marked
1-5 bpm = minimal
0 bpm = absent

W/ Accelerations = moderate
No apparent baseline = marked

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This type of deceleration starts at the same time as the contractions

This happens secondary to ________

Early

secondary to head compressions

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When do late contractions start?

This happens secondary to ________

T/F: Late contractions are the most worrisome

After the peak of contraction

Happens due to uteroplacental insufficiency

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T/F: Variable decelerations start after contractions This happens secondary to ________

F: it has no relation to contractions Happens due to umbilical cord compression

What does the ff CST results mean? Negative- Positive- Equivocal Suspicious- Equivocal Hyperstimulatory- Unsatisfactory

Negative- there is no deceleration in every contraction Positive- there are LATE decelerations after more than 50% or more contractions Equivocal Suspicious- if there are variable decelerations or if there are late decelerations after NOT more than 50% of contractions Equivocal Hyperstimulatory- more than 3 contractions in 10 mins Unsatisfactory- fewer than 3 contractions in 10 mins

T/F: Non-stress test is done to identify Uteroplacental insufficiency, while stress test is to test fetal condition

F- Contraction stress test- to identify UPI Non stress- to test fetal condition

The Non-stress test is based on what principle?

That the heart rate of a non-acidemic fetus will increase in response to fetal movement

What is the goal of reactive NST? T/F: Accelerations are accepted irrespective of fetal movements T/F: You can use loud external sounds to provoke the fetus, using a vibroacoustic stimulator with a stimulus of 1-2 seconds for up to 3 times T/F: Sleep-wake cycle is considered

To have 2 or more accelerations in 20 minutes T T T

Non-reactive NST is done at least _____- minutes

40 mins, can extend up to 80 minutes

What is the interval for NST testing?

Generally weekly testing for stable high risk maternal conditions (Pre gestational diabetes, chronic htn, SLE)

Nuchal translucency is done from __ to ___ weeks AOG with CRL of _ to ____mm What to do if the CRL is outside the recommended range? When is nuchal translucency increased? T/F: If thickened, amniocentesis, congenital scan, or non-invasive prenatal testing must be requested

11 to 13 and 6/7 weeks AOG with CRL of 45-84 mm cannot interpret if outside In conditions such as aneuploidy, congenital anomalies (cystic hygroma, congenital heart) T

Fetal weight is estimated via ultrasonography during the ___ trimester Fetal weight is based on: Machine used for ultrasound

2nd (starting at 14 weeks) Biparietal diameter, head circumference, abdominal circumference, femoral length Hadlock scale

When is the fetal weight considered abnormal? What to do if there's a growth disorder?

If it is less than the 10th percentile or more than the 90th percentile Repeat scan after 2 weeks

Book recommendation when fetal anomaly scan is done

18-22 weeks AOG

What is being looked into using the biophysical profile? what is its premise?

FANTy size B Fetal Breathing Amniotic Fluid Non Stress Test Tone (Fetal) Body or Limb Movements Multiple parameters of well being are better predictors of outcome than any single parameter

How is biophysical profile done?

All parameters are checked in a maximum of 30 minutes. A score of 2 is present, 0 if none. Total is 10, sometimes 8 (without nonstress test)

This is an indicator of chronic fetal asphyxia or hypoxia

Amniotic fluid

What does fetal oliguria in an anatomically normal fetus indicate?

There's redistribution of fetal blood away from the kidneys and into the "more vital" organs like the heart and brain

NST and fetal breathing movements are suppressed when the pH falls below ___, and abolished below _____

7.2; 7.1

<2cm of single vertical pocket of fluid indicates = >/2 to 8 cm= >/8 cm=

<2cm = oligohydramnios >/2 to 8 cm= normal >/8 cm= polyhydramnios

What is the goal of fetal doppler velocimetry? T/F: There is a faster blood flow in bigger vessels and a slower flow in constricted vessels What vessels are checked ?

To determine the velocity of blood flow in fetal blood vessels T DUMU- Ductus Venosus, Uterine Artery, Umbilical Artery, Middle cerebral artery

Explain the doppler principle:

The frequency of the reflected energy depends on the velocity of the moving boundary

This is the only maternal blood vessel checked using doppler Why is it checked?

Uterine artery -It represents vascular resistance in the maternal compartment which should decline normally in the first half of pregnancy due to trophoblast invasion and remodeling of uterine vessels

What is the main indication for fetal doppler velocimetry?

IUGR although it can also be used for preeclampsia, amniotic fluid abnormalities, twin pregnancy, fetal anemia

What does it mean if the decrease in vascular resistance of the uterine artery does not occur? T/F: Increased vascular resistance increases risk for IUGR development Uterine artery velocimetry can be done as early as ___ weeks?

There is abnormal remodeling of the spinal arteries T + preeclampsia 11-13 weeks

This artery or vein is reflective of fetoplacental circulation

Umbilical Artery

T/F: Umbilical artery constriction is not used in isolation as indicator for delivery

T/F: In normal conditions, the blood vessels should constrict as the placenta develops

F- it should dilate > progressive increase in end diastolic velocity due to decreased impedance to flow Constrictions are abnormal as it increases vascular resistance in the uterine artery due to increased obstruction to flow

Umbilical Artery doppler is a test to determine _______

IUGR

Function of middle cerebral artery doppler T/F: In normal conditions, there is increased vascular resistance in the MCA; shunting during hypoxic states would indicate dilation What is the equation of cerebroplacental ratio? What values are indicative of normal and brain sparing? T/F: MCA doppler assesses for fetal anemia

To assess presence of brain sparing in IUGR, and if the baby is compensating during hypoxemic states T Cerebroplacental ratio = middle cerebral artery pulsatility index / umbilical artery PI >1 = normal <1 - brain sparing T- most common cause is immune hydrops

This is reflective of fetal venous circulation If abnormal, what does it indicate? T/F: This test is routinely used for fetal growth restriction surveillance

Ductus Venosus Doppler If abnormal = cardiac dysfunction F- it is not recommended to be of routine use

Explain the placental insufficiency in Doppler:

There is an increased resistance in the umbilical artery likely d/t abnormal remodelling of the spinal arteries > the cerebroplacental ratio decreases > if <1 = brain sparing The blood going back to the mom (deoxygenated blood) will be less as seen by absent or reversed end diastolic velocity in the umbilical artery > right side of the heart will be affected > absent or reversed wave of ductus venosus and umbilical vein pulsations

This is the primary adaptive response of the fetus to stress (respiratory or nutritive insufficiency)

decreased fetal growth rate

This is the secondary adaptive response of the fetus to stress (respiratory or nutritive insufficiency)

Fetal energy conservation (decreased fetal movement and heart rate reactivity) Circulatory redistribution (falling cerebral flow impedance, rising umbilical and aortic impedance) Fetal growth preferred over placental growth Increased efficiency of placental exchange Polycythemia

Absent end diastolic flow in umbilical arteries indicates (primary/secondary adaptive response or progressive decompensation)

Progressive decompensation

Fetal growth preferred over placental growth indicates (primary/secondary adaptive response or progressive decompensation)

secondary adaptive response

Declining amniotic fluid leading to oligohydramnios indicates (primary/secondary adaptive response or progressive decompensation)

Progressive decompensation

Indications for antepartum testing

Pregnancies with increased risk for IUFD

When to start antepartum testing?

Generally starts at 32 weeks but can be done as early as 26 weeks in cases like IUGR