QUIZ 2 SUMMARY TABLE 2

110-160 bpm

What is the normal range for Fetal Heart Rate (FHR)?

FHR <110 bpm

What defines bradycardia in FHR?

FHR >160 bpm

What defines tachycardia in FHR?

Oxygenation drop, umbilical blood flow issues, uterine blood flow reduction

What are some causes of bradycardia?

Maternal/fetal infection, fever, stimulant drugs

What are some causes of tachycardia?

Fluctuations in baseline FHR, visualized as amplitude from peak to trough (bpm)

What is the definition of variability in FHR?

Push and pull of parasympathetic & sympathetic nervous system

What is the mechanism behind FHR variability?

Highest peak - Lowest trough

How is FHR variability calculated?

6-25 bpm

What is considered normal FHR variability?

5-25 bpm

What is considered moderate (good) FHR variability?

>25 bpm

What is considered marked FHR variability?

What is considered minimal FHR variability?

Undetectable

What is considered absent FHR variability?

Hypoxia/Acidosis, Fetal sleep cycles, Congenital anomalies, Extreme prematurity, Fetal tachycardia, Preexisting neurologic abnormality, Medications

List some causes of decreased FHR variability

Analgesics, Barbiturates, Tranquilizers, Phenothiazines, Parasympatholytics, General anesthetics, Magnesium sulfate

Name some medications that can cause decreased FHR variability

Abrupt increase in FHR from baseline

What is the definition of an acceleration in FHR?

Decrease in FHR due to various causes

What is the definition of a deceleration in FHR?

What is the time to peak for accelerations?

Varies by type

What is the time to peak for decelerations?

≥15 bpm lasting ≥15 sec (≥32 weeks); ≥10 bpm lasting ≥10 sec (

What is the threshold for accelerations?

Fetal movement, stimulation

What are common causes of accelerations?

Head compression, uteroplacental insufficiency, cord compression

What are some causes of decelerations?

Not related to contractions

How are accelerations related to contractions?

Some types occur with contractions (Early & Late), others are independent (Variable)

How are decelerations related to contractions?

Gradual decrease & return to baseline, symmetrical; Nadir (lowest point) aligns with contraction peak

What are the key characteristics of early decelerations?

Head compression

What is the cause of early decelerations?

Benign, expected in labor

What is the significance of early decelerations?

Gradual decrease & return to baseline, symmetrical; Nadir occurs after contraction peak

What are the key characteristics of late decelerations?

Uteroplacental insufficiency

What is the cause of late decelerations?

Concerning—indicates fetal hypoxia

What is the significance of late decelerations?

Abrupt drop & return to baseline, unpredictable; Can occur before, during, or after contractions

What are the key characteristics of variable decelerations?

Umbilical cord compression

What is the cause of variable decelerations?

Common in labor, needs evaluation

What is the significance of variable decelerations?

FHR drop ≥15 bpm lasting >2 min but

What defines a prolonged deceleration?

Severe hypoxia, cord compression, maternal hypotension

What are some causes of prolonged decelerations?

Requires urgent assessment

What is the significance of prolonged decelerations?

Test fetal condition via FHR response to movement

What is the purpose of a Non-Stress Test (NST)?

Stimulate fetal movement if NST is nonreactive

What is the purpose of a Vibroacoustic Stimulation Test (VAS)?

Test uteroplacental function via FHR response to contractions

What is the purpose of a Contraction Stress Test (CST)?

FHR should increase with fetal movement

What is the expected mechanism of an NST?

Loud external sound startles fetus, provoking HR acceleration

What is the expected mechanism of a VAS?

Induce or monitor contractions and observe FHR changes

What is the procedure for a CST?

Reactive: FHR acceleration present (≥15 bpm for ≥15 sec)

What is a positive result for an NST?

FHR acceleration present after stimulus

What is a positive result for a VAS?

Negative CST: No late decelerations

What is a positive result for a CST?

Nonreactive: No accelerations

What is a negative result for an NST?

No acceleration (suggests sleep cycle or hypoxia)

What is a negative result for a VAS?

Positive CST: Late decelerations present (concerning)

What is a positive result for a CST?

Assess high-risk pregnancies, suspected placental insufficiency

What are the indications for an NST?

None

What are the contraindications for an NST?

Preterm labor risk factors (e.g., PROM, placenta previa, multiple gestations)

What are the contraindications for a CST?

Passive test, no external stimulation

What are the key differences of an NST?

Stimulus applied to wake the fetus

What are the key differences of a VAS?

Actively induces contractions to assess function

What are the key differences of a CST?

Measure fetal growth

What is the purpose of Fetal Biometry?

Assess fetal well-being via ultrasound and NST

What is the purpose of a Biophysical Score (BPS)?

Assess blood flow in maternal & fetal vessels

What is the purpose of Doppler Velocimetry?

Detect growth abnormalities

What is the main use of Fetal Biometry?

Monitor fetal oxygenation and acid-base status

What is the main use of a BPS?

Evaluate placental function and fetal circulation

What is the main use of Doppler Velocimetry?

Head circumference, Abdominal circumference, Femur length

What are the key measurements in Fetal Biometry?

Fetal breathing, Fetal movement, Fetal tone, Amniotic fluid, NST (optional)

What are the key measurements in a BPS?

Umbilical artery, Ductus venosus, Middle cerebral artery, Uterine artery

What are the key measurements in Doppler Velocimetry?

Compare EFW to gestational norms

How is Fetal Biometry interpreted?

Score 8/8 or 10/10 → Normal; Lower scores → Possible hypoxia/asphyxia

How is a BPS interpreted?

Normal = Low resistance in umbilical & uterine arteries; Abnormal = Increased resistance or reversed flow

How is Doppler Velocimetry interpreted?

Placental insufficiency

What is the most common cause of abnormality in Fetal Biometry?

Fetal distress, hypoxia, or low amniotic fluid

What is the most common cause of abnormality in a BPS?

Uteroplacental insufficiency

What is the most common cause of abnormality in Doppler Velocimetry?

Assess placental blood flow

What is the purpose of Umbilical Artery Doppler?

Detect placental insufficiency

What are you trying to detect when assessing placental blood flow?

Systole: Increased flow (upstroke); Diastole: Progressive forward flow

What are the normal flow characteristics in Umbilical Artery Doppler?

Absent End Diastolic Flow (EDF): No forward flow; Reversed EDF: Blood flows backward

What are the abnormal flow characteristics in Umbilical Artery Doppler?

Vasodilated (low resistance, good perfusion)

What is the placental vessel condition in a normal Umbilical Artery Doppler?

Vasoconstricted (high resistance, poor perfusion)

What is the placental vessel condition in an abnormal Umbilical Artery Doppler?

Present → Good placental function; Absent EDF (60% vessel obliteration) → Fetal distress in 5-7 days; Reversed EDF (70% vessel obliteration) → Fetal demise in 4-5 days

What is the interpretation of EDF in Umbilical Artery Doppler?

Adequate oxygen & nutrients to fetus

What is the implication of normal Umbilical Artery Doppler results?

High risk of fetal compromise, hypoxia, or demise

What is the implication of abnormal Umbilical Artery Doppler results?

Circle of Willis (brain)

What is the location of the Middle Cerebral Artery (MCA)?

Connects umbilical vein to heart

What is the location of the Ductus Venosus (DV)?

Assess fetal oxygenation & brain sparing

What is the purpose of Middle Cerebral Artery (MCA) Doppler?

Assess fetal cardiac function

What is the purpose of Ductus Venosus (DV) Doppler?

Vasoconstricted (brain takes priority)

What is the normal state of the Middle Cerebral Artery (MCA)?

Normal forward flow

What is the normal state of the Ductus Venosus (DV)?

Vasodilation (brain sparing)

What is the response to hypoxia in the Middle Cerebral Artery (MCA)?

Increased central venous pressure

What is the response to hypoxia in the Ductus Venosus (DV)?

Brain

What is the end-organ at risk when assessing the Middle Cerebral Artery (MCA)?

Heart

What is the end-organ at risk when assessing the Ductus Venosus (DV)?

Vasodilation followed by vasoconstriction; Reduced systemic blood flow; Fetal distress if prolonged hypoxia

What are the signs of distress in the Middle Cerebral Artery (MCA)?

Increased right ventricular end-diastolic pressure; Cardiac dysfunction; Higher risk of fetal compromise

What are the signs of distress in the Ductus Venosus (DV)?

If MCA Doppler shows late vasoconstriction → Fetal distress

When should you intervene based on Middle Cerebral Artery (MCA) Doppler results?

Abnormal DV Doppler → High risk for fetal compromise

When should you intervene based on Ductus Venosus (DV) Doppler results?

≥10 kicks in 2 hours

What are the normal findings in a Fetal Kick Count?

Reactive: Normal variability

What are the normal findings in an NST/CTG?

8-10: Normal, low risk

What are the normal findings in a BPS?

Normal flow, continued perfusion

What are the normal findings in an Umbilical Artery (UA) Doppler?

Normal resistance & flow

What are the normal findings in a Middle Cerebral Artery (MCA) Doppler?

Normal venous flow

What are the normal findings in a Ductus Venosus (DV) Doppler?

What are the abnormal findings in a Fetal Kick Count?

Non-reactive: Requires secondary test; Decelerations: Investigate cause

What are the abnormal findings in an NST/CTG?