Updated: 4/8/2019

Intrapartum Fetal Assessment

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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 fetal heart monitor is noted. Maternal repositioning is performed. (Variable decelerations)
Biophysical Profile (BPP)
  • Five measurements of fetal well being, each rated on scale of 0 or 2
    • measure
      • 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 
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 
    • causes include
      • 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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Questions (6)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
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(M2.OB.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? Review Topic

QID: 109557
FIGURES:
1

Epidural analgesia

15%

(6/41)

2

Cord compression

39%

(16/41)

3

Vasa previa

2%

(1/41)

4

Fetal head compression

10%

(4/41)

5

Uteroplacental insufficiency

34%

(14/41)

M2

Select Answer to see Preferred Response

PREFERRED RESPONSE 2

(M2.OB.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. The patient undergoes external fetal monitoring. With vibroacoustic stimulation, the patient feels eight movements over two hours. What is the best next step in management? Review Topic

QID: 109560
1

Reassurance

0%

(0/0)

2

Induction of labor

0%

(0/0)

3

Oxytocin challenge

0%

(0/0)

4

Biophysical profile

0%

(0/0)

5

Inpatient monitoring

0%

(0/0)

M2

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

(M2.OB.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? Review Topic

QID: 105265
FIGURES:
1

Fetal head compression

78%

(18/23)

2

Utero-placental insufficiency

0%

(0/23)

3

Cord compression

13%

(3/23)

4

Fetal distress

4%

(1/23)

5

Congenital heart block

0%

(0/23)

M2

Select Answer to see Preferred Response

PREFERRED RESPONSE 1
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