Updated: 10/11/2021

Intrapartum Fetal Assessment

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https://upload.medbullets.com/topic/120355/images/variable.jpg
https://upload.medbullets.com/topic/120355/images/early_decel_-_moises_dominguez.jpg
https://upload.medbullets.com/topic/120355/images/variable_decel.jpg
https://upload.medbullets.com/topic/120355/images/late_decel_-_moises_dominguez.jpg
https://upload.medbullets.com/topic/120355/images/late-decelerations.jpg
https://upload.medbullets.com/topic/120355/images/early-decelerations.jpg
https://upload.medbullets.com/topic/120355/images/new_tracing.jpg
https://upload.medbullets.com/topic/120355/images/tracing.jpg
https://upload.medbullets.com/topic/120355/images/sinusoidal.jpg
Snapshot
  • A 35-year-old woman at 42 weeks of gestation presents for an induction of labor due to postterm pregnancy. She reports positive fetal movement, and denies vaginal bleeding. After amniotomy is performed, a change in the fetal heart rate is noted, as seen in the tracing in the image. Maternal repositioning is performed. (Variable decelerations)  
Introduction
  • Overview
    • intrapartum fetal assessments are performed to assess fetal well-being during labor and delivery
      • biophysical profile (BPP)
      • fetal heart rate (FHR) monitoring
        • electronic fetal monitoring (EFM) is the most common method to assess the fetus during labor
Biophysical Profile (BPP)
  • Five measurements of fetal well being, each rated on scale of 0 or 2
    • measurements
      • fetal breathing
      • gross body movements
      • fetal tone
        • extremity extension and flexion
      • amniotic fluid volume
      • nonstress test (NST)
  • Scoring
    • 8-10 is reassuring
    • 6 is equivocal
      • delivery if > 36 weeks
      • repeat BPP in 24 hours if < 36 weeks
    • ≤ 4 is abnormal
      • requires immediate intervention, prompt delivery 
Fetal Heart Rate (FHR)
  • Normal FHR 120-160/min
  • Tachycardia is FHR > 160/min
    • causes include
      • maternal fever
      • fetal hypoxia
      • prematurity
      • anemia (maternal or fetal)
      • chorioamnionitis
      • hyperthyroidism
  • Bradycardia is FHR < 110/min for > 10 minutes
    • causes include
      • congenital heart block
      • maternal β-blockers
  • FHR variability
    • reliable indicator of fetal well being
    • causes of decreased variability include
      • fetal hypoxia
      • congenital heart anomalies
Electronic Fetal Heart Rate Monitoring (EFM) Tracing Interpretation
  • Accelerations
    • FHR at least 15/min above baseline for 15 seconds and < 2 minutes in a 20 minute period when gestational age is > 32 weeks or 10/min for 10 seconds when gestational age is < 32 weeks
      • considered a reactive NST (needs the presence of at least 2 accelerations)  
    • suggests fetal well being
    • if this was a NST during pregnancy (not intrapartum), management would be routine-follow-up 
  • Early decelerations
    • FHR (not below 100/min) that coincide with uterine contraction
      • nadir of the deceleration meets the apex of the uterine contraction
    • results from pressure on fetal head (fetal head compression) resulting in vagus nerve stimulation and reflex bradycardia 
    • physiologic and not harmful to fetus  
  • Variable decelerations
    • may not coincide with uterine contractions
    • rapid in FHR (often < 100/min) with variable recovery
    • reflex mechanism due to umbilical cord compression  
      • rupture of membrane can lead to umbilical artery compression 
    • correct by shifting maternal position or amnioinfusion if membranes ruptured 
      • considered first-line
      • if maternal repositioning does not improve FHR tracing, amnioinfusion can be considered
  • Late decelerations
    • begins after uterine contraction has started
    • associated with uteroplacental insufficiency and viewed as potentially dangerous 
    • potential causes  
      • placental abruption
      • maternal diabetes
      • maternal anemia
      • maternal sepsis
      • postterm pregnancy
      • hyperstimulated uterus
    • repetitive late develerations require intervention
  • Sinusoidal tracing
    • sine-wave like pattern
    • associated with increased morbidity and mortality
    • indicative of severe fetal anemia 
      • e.g., severe hypoxia and Rh disease

 

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(M2.OB.17.4867) A 28-year-old G1P0 woman at 42 weeks gestation is admitted to the maternity ward for induction of labor. She states that her prenatal care has been notable for gestational hypertension. She has been taking her multivitamin daily. She feels fetal movement and denies any vaginal bleeding. Her temperature is 98.6°F (37°C), blood pressure is 107/54 mmHg, pulse is 72/min, and respirations are 20/min. Her cervix is 0 cm dilated, and the fetus is in cephalic position. The fetal heart monitor shows a heart rate of 130/min. She agrees to have an epidural catheter placed for analgesia. Shortly thereafter, amniotomy is performed. No vaginal bleeding is observed. While attending to documentation of the procedure, the nurse calls your attention to a change in the fetal heart monitor, shown in Figure A. What is the most likely cause for this finding?

QID: 109557
FIGURES:
1

Epidural analgesia

17%

(10/58)

2

Cord compression

41%

(24/58)

3

Vasa previa

2%

(1/58)

4

Fetal head compression

10%

(6/58)

5

Uteroplacental insufficiency

29%

(17/58)

M 6 C

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(M2.OB.17.4867) A 28-year-old G1P0 woman who is 30 weeks pregnant presents to the women's health center for a prenatal checkup. She is concerned that her baby is not moving as much as usual over the past five days. She thinks she only felt the baby move eight times over an hour long period. Her prenatal history was notable for morning sickness requiring pyridoxine. Her second trimester ultrasound revealed no abnormal placental attachment. She takes a multivitamin daily. Her temperature is 98.6°F (37°C), blood pressure is 120/70 mmHg, pulse is 80/min, and respirations are 16/min. The patient's physical exam is unremarkable. Her fundal height is 28 cm, compared to 26 cm two weeks ago. The fetal pulse is 140/min with no accelerations. The patient undergoes external fetal monitoring. With vibroacoustic stimulation, the patient feels eight movements over two hours with no fetal heart rate accelerations. What is the best next step in management?

QID: 109560
1

Reassurance

33%

(5/15)

2

Induction of labor

0%

(0/15)

3

Oxytocin challenge

20%

(3/15)

4

Biophysical profile

33%

(5/15)

5

Inpatient monitoring

7%

(1/15)

M 6 C

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(M2.OB.15.95) You are the intern on the labor and delivery floor. Your resident asks you to check on the patient in Bed 1. She is a 27-year-old prima gravida with no significant past medical history. She has had an uncomplicated pregnancy and has received regular prenatal care. You go to her bedside and glance at the fetal heart rate tracing (Image A). What is the most likely cause of this finding?

QID: 105265
FIGURES:
1

Fetal head compression

76%

(22/29)

2

Utero-placental insufficiency

0%

(0/29)

3

Cord compression

17%

(5/29)

4

Fetal distress

3%

(1/29)

5

Congenital heart block

0%

(0/29)

M 6 E

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(M2.OB.13.195) A 29-year-old G2P1001 woman at 39 weeks gestation presents to labor and delivery triage with intermittent lower abdominal pain. Her pregnancy has been followed and she is currently taking folate and a multivitamin. Her temperature is 98.0°F (36.7°C), blood pressure is 129/82 mmHg, pulse is 110/min, respirations are 22/min, and oxygen saturation is 98% on room air. The fetal heart rate monitoring strip depicted in Figure A is obtained. Which of the following best explains this fetal heart rate tracing?

QID: 105365
FIGURES:
1

Compression of the fetal head

17%

(2/12)

2

Compression of the umbilical cord

25%

(3/12)

3

Normal fetal heart rate tracing

8%

(1/12)

4

Sleeping fetus

17%

(2/12)

5

Uteroplacental insufficiency

33%

(4/12)

M 6 E

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