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Questions and Answers
What is an indication for using a cardiotocograph (CTG) for fetal monitoring?
During a non-stress test (NST), how long should the fetal heart rate (FHR) be monitored at minimum?
Which of the following statements is true regarding fetal heart baseline rates?
What is a common cause of fetal tachycardia?
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Which of the following characteristics indicates decreased fetal heart rate variability?
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What defines an acceleration in fetal heart rate during monitoring?
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Which condition could lead to decreased fetal heart rate variability?
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Which method is used for acoustic stimulation during fetal monitoring?
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What is the significance of fetal movement counting during pregnancy?
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When should a mother start counting fetal movements?
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What is the expected duration for a mother to feel 10 fetal movements?
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What is quickening and when does it typically occur?
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Which of the following factors can influence a mother's perception of fetal movement?
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What does the HC/AC ratio indicate during second and third-trimester ultrasounds?
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What is the primary purpose of a basic first-trimester ultrasound?
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What indicates a normal sleeping pattern for the fetus?
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What does a digital fetal scalp stimulation leading to an acceleration in fetal heart rate indicate?
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How are early decelerations characterized in relation to uterine contractions?
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What type of fetal heart rate deceleration is associated with cord compression?
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What does a late deceleration indicate regarding placental function?
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What is the main significance of using electronic fetal monitoring (EFM) during labor?
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What is the recommended timing for intermittent auscultation in the first stage of labor for low-risk women?
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What duration and intensity characterizes variable decelerations?
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What potential outcome should EFM be cautious to avoid when used on low-risk women?
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Study Notes
Fetal Movement
- Fetal movement is a key indicator of fetal health
- A change in the normal number of fetal movements may indicate the fetus is under stress
- The simplest way to chart movements is to record the amount of time it takes to feel 10 movements. It should take no more than 2 hours.
- Most fetuses have circadian rhythms and are more active in the evening hours.
- A fetus will often be more active an hour after the mother eats.
- The mother will likely begin feeling fetal movements (quickening) around 16-25 weeks of pregnancy. The average is 20-22 weeks, but can be earlier for those who have had multiple pregnancies.
Fetal Movement Count
- A fetus spends 10% of its time making gross fetal body movements
- It makes approximately 30 movements each hour
- Active periods for fetal body movement typically last about 40 minutes
- Quiet periods generally last about 20 minutes
- The longest period without fetal movement should not be more than 75 minutes
Factors Affecting Perception of Fetal Movement
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Fetal and Placental factors:
- Placental location
- Length and type of fetal movements
- Amniotic fluid volume (AFV)
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Maternal factors:
- Parity
- Obesity
Ultrasound for Fetal Parameters
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Basic Ultrasound - Done at 10-14 weeks.
- Number of fetuses
- Fetal heart and viability
- Gestational age - CRL
- Any gross anomaly - anencephaly, limb reduction defects
- Nuchal translucency
- Placental localization
- Cervical length
- Maternal pelvic masses
2nd & 3rd Trimester Ultrasound
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Serial Measurements - Done at 10-14 weeks.
- BPD, AC, HC, FL (Growth US Scan)
- HC/AC Ratio: Exceeds 1 before 32 weeks. After 34 weeks, it falls below 1. In symmetric IUGR, it remains normal. This ratio can identify 85% of IUGR fetuses.
Internal Cardiotocograph
- Uses an electronic transducer connected directly to the fetal scalp through the cervical opening.
- Connected to a monitor
- Requires ruptured amniotic membranes
- Requires a dilated cervix (2 cm)
- Cephalic presentation with the presenting part down against the cervix
Non-Stress Test (NST) Method
- Patient positioned in a lateral tilt position
- FHR and uterine activity monitored with an external transducer
- FHR monitored for 20 minutes
- Monitoring extended for 40 minutes in cases to compensate for sleep cycles - Extended NST
- Acoustic stimulation used if the fetus is not reactive.
Intrapartum CTG Interpretation
- Baseline Fetal Heart Rate (FHR)
- Baseline FHR Variability
- Presence of Accelerations
- Decelerations
- Uterine Activity (contractions)
Fetal Heart Baseline
- Differentiate between fetal and maternal heartbeats.
- Baseline FHR usually ranges between 110 and 160 beats/minute.
- Fetal Tachycardia - Baseline FHR greater than 160 beats per minute
- Fetal Bradycardia - Sustained fetal heart rate less than 110 beats per minute
Causes of Fetal Tachycardia
- Maternal fever
- Chorioamnionitis
- Fetal sepsis
- Drugs (Atropine, Phenothiazines, Beta-sympathomimetics)
- Tachyarrhythmias
- Fetal heart failure
- Severe fetal anemia, fetal hydrops
- Maternal hyperthyroidism
Variability
- Variability normally ranges between 5 and 25 beats/minute.
- Intermittent periods of reduced baseline variability are normal, especially during sleep.
Causes of Decreased Variability
- Hypoxemia/acidosis
- Fetal sleep cycles
- Drugs (Analgesics, barbiturates, phenothiazines, anesthetics)
- Prematurity
- Arrhythmias
- Pre-existing neurological abnormality
- Congenital anomalies
Accelerations
- Increase in FHR greater than or equal to 15 bpm for greater than or equal to 15 seconds from the onset to return to baseline.
- The presence of accelerations, even with reduced baseline variability, is generally a sign that the baby is healthy.
- The absence of accelerations on an otherwise normal cardiotocograph does not indicate fetal acidosis.
- Digital fetal scalp stimulation (during vaginal examination) that leads to an acceleration in fetal heart rate is a sign that the baby is healthy.
Decelerations
- Decreases in fetal heart rate from the baseline by at least 15 bpm, lasting for at least 15 seconds.
Types of Decelerations
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Early Decelerations:
- Begin at the start of uterine contraction and end with conclusion of contraction.
- The onset, nadir, and recovery of the deceleration are with the beginning, peak, and ending of the contraction, respectively (mirror like).
- Related to head compression.
- Early decelerations are a benign finding caused by a vasovagal response as a result of fetal head compression by the contraction.
- No intervention necessary. Just continue to watch for any changes.
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Variable Decelerations:
- Variable in duration, intensity, and timing.
- Abrupt(sudden) decrease in FHR of > 15 beats per minute measured from the most recently determined baseline rate.
- The onset of deceleration to nadir is less than 30 seconds. The deceleration lasts > 15 seconds and less than 2 minutes.
- Related to cord compression.
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Late Decelerations:
- Gradual decrease in FHR with onset of deceleration to nadir > 30 seconds.
- Onset of the deceleration occurs after the beginning of the contraction, and the nadir of the deceleration occurs after the peak of the contraction.
- Related to decreased uteroplacental perfusion.
EFM Learning Points
- It is used to identify intrapartum hypoxia, a significant cause of fetal death and disability. Fetal hypoxia can lead to fetal asphyxia and death.
- It should not be used unless indicated as it increases the rates of cesarean section and instrumental delivery in low-risk women.
- It has become an integral component of labor management in high-risk women.
Intermittent Auscultation of Fetal Heart Rate
- Intermittent auscultation of the fetal heart rate can be used for women at a low risk of complications in the established first stage of labor.
- Auscultate immediately after a contraction for at least 1 minute, at least every 15 minutes in the first stage of labor, and at least every 5 minutes in the second stage. Record as a single rate.
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Description
Explore the significance of fetal movements as a key indicator of fetal health. This quiz covers the normal range of movements, their timing, and what deviations may signal potential stress. Learn how to monitor fetal activity effectively during pregnancy.
