Updated: 3/11/2019

Prenatal Care

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Questions
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Evidence
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Diagnosis
  • Symptoms of pregnancy
    • amenorrhea
    • urine frequency
    • breast engorgement
      • treat with breasfeeding/pumping or cold compress 
    • nausea
    • bluish discoloration of vagina, vulva, and cervix due to vascular congestion (Chadwick's sign)
    • softening of cervix
  • Urine Pregnancy Test (UPT)
    • detects hCG or B subunit
      • sensitive to 1-2 weeks
  • Ultrasound
    • most accurate method to detect fetal size
      • gestational Sac - 5 weeks
      • fetal image detected at 6-7 weeks
      • cardiac activity at 8 weeks
Initial Workup-First visit
  • Estimated date of confinement (EDC)
    • Nageles's Rule: LMP + 7 days - 3 mos + 1 yr
      • Ex.) LMP 4/19/12, EDC = 1/26/13
      • calculation based on regular 28 day cycle (only 20-25%)
    • sonogram estimation
      • crown-rump length (CRL)
      • biparietal diameter (BPD)
      • of note, sonogram estimation of EDC is more accurate earlier in pregnancy than later
  • Complete pelvic exam
    • estimate uterine size
    • PAP smear
    • cultures for gonorrhea and chlamydia
  • Labs  
    • CBC
    • blood type with Rh status
    • urinalysis and culture
      • asymptomatic bacteriuria should be treated in pregnant women
      • can progress to pyelonephritis in pregnant women due to urinary stasis and ureteral dilation (right more than left)
    • RPR test for syphilis 
    • Rubella titer 
      • if not already immune DO NOT VACCINATE
        • recall MMR is a live virus vaccine
    • TB skin testing
    • offer HIV/HBV antibody test 
    • sickle cell prep
    • TSH
      • hypothyroid women should have their dose of levothyroxine increased if found to be pregnant. During pregnancy, increased circulating levels of thyroxine-binding globulin (TBG) and increased plasma volume increase demand for T4
  • Genetic counseling indicated by history
  • Recommend 25-35 lb weight gain during pregnancy
  • Consider folate, iron & multivitamins
  • Inactivated influenza vaccination is recommended for patients that will be pregnant during influenza season 
First Trimester
  • Visit every 4 weeks
  • Evaluate
    • weight gain / loss
    • BP
    • pedal edema
    • fundal height
    • urine dip for glucosuria and proteinuria
      • trace glucose is normal due to GFR
      • trace protein is not normal and should be evaluated
  • Cell-free fetal DNA 
    • non-invasive
    • very sensitive/specific
    • can order at 10 weeks or greater
    • can confirm with CVS or amniocentesis
  • Chorionic villus sampling (CVS)
    • definition
      • a procedure where small samples of placenta are acquired in order to
        • perform a prenatal genetic analysis (e.g., DNA analysis and cytogenetics)
    • CVS is typically performed between
      • 10 and 13 weeks of gestation
    • indications
      • maternal age is 35 years or older
      • prior child had a genetic disorder (e.g., Cystic fibrosis) and chromosomal abnormalities (e.g., Down syndrome)
      • parents are carriers of a genetic disorder
      • first trimester ultrasound examination suggests a congenital anomaly
      • abnormal aneuploidy screening result
    • risks
      • maternal alloimmunization (relative contraindication)
      • vertical transmission of infection (e.g., HIV)
    • complications
      • miscarriage
      • amniotic fluid leakage
 Estimate Gestational Age by Uterine Size
12 weeks At pubic symphysis
16 weeks Midway from symphysis to umbilicus
20 weeks At umbilicus
20-36 weeks Height (in cm) above pubic symphysis correlates with weeks of gestation
 
Second Trimester
  • Continue visits every 4 weeks
  • 15-18 weeks
    • offer triple marker screen (hCG, estriol, AFP)
      • used to detect neural tube defects or trisomies
  • 16-20 weeks 
    • amniocentesis if > 35 years old or history indicates
  • 17 weeks 
    • document movement
  • 24 weeks
    • glucose screening
  • 25 -28 weeks 
    • repeat Hct
Third Trimester
  • Every 4 weeks until week 28, then every two weeks, then every week after 36.
  • Routine third trimester tests
    • urine analysis 
    • blood glucose
  • Inquire about preterm labor symptoms
    • vaginal bleeding
    • contractions
    • rupture of membranes
  • 28-30 weeks
    • give RhoGAM if indicated
  • 28-32 weeks
    • mothers with pre-gestational diabetes should undergo twice weekly nonstress testing until delivery 
  • 35-37 weeks
    • screen for Streptococcus agalactiae (Group B Strep)
  • 36-40 weeks 
    • cervical chlamydia and gonorrhea cultures if indicated
Summary Table
 
Prenatal Tests
Prental Test
Gestational Age (Weeks)
Extra
First trimester screen
  • 11-14
  • Ultrasound for nuchal translucency
  • PAPP-A
    • levels are seen in chromosomal abnormalities
  • hCG
    • levels are seen in chromosomal abnormalities
Cell free fetal DNA
  • ~10
  • Analyze fetal DNA in maternal blood
  • Screens for trisomies of 13, 18, and 21
  • Positive test results should be followed by CVS or amniocentesis
Chorionic villus sampling (CVS)
  • 11-14
  • Collect placental tissue to test for chromosomal and genetic abnormalities
Quadruple screen
  • 16-18
  • AFP, hCG, estriol, inhibin
    • AFP = neural tube or abdominal wall defects
    • ↑ hCG and inhibin and ↓ AFP and estriol = Down syndrome
    • AFP, hCG, and estriol = Edwards syndrome
Amniocentesis
  • 15-20
  • Collect amniotic fluid to diagnosis chromosomal abnormalities
Glucose challenge test
  • 24-28
  • 1 hr glucose challenge test
  • If abnormal followed by glucose tolerance test
Group B strep test
  • 35-37
  • Swab the lower genital tract for colonization by GBS
 
 

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Questions (10)
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
Calculator

(M2.OB.4870) An 18-year-old G1P0 woman who is 10 weeks pregnant presents for her first prenatal visit. She reports nausea with occasional vomiting but denies bleeding, urinary symptoms, or abdominal pain. She just graduated high school and works at the local grocery store. She does not take any medications and has no known drug allergies. Physical examination is unremarkable. Initial laboratory studies reveal the following:

Serum:
Na+: 140 mEq/L
Cl-: 100 mEq/L
K+: 4.0 mEq/L
HCO3-: 24 mEq/L
BUN: 10 mg/dL
Glucose: 100 mg/dL
Creatinine: 1.0 mg/dL
Thyroid-stimulating hormone: 2.5 µU/mL
Ca2+: 9.5 mg/dL
AST: 25 U/L
ALT: 20 U/L

Leukocyte count: 10,000 cells/mm^3 with normal differential
Hemoglobin: 14 g/dL
Hematocrit: 42%
Platelet count: 200,000 /mm^3

Urine:
Epithelial cells: few
Glucose: negative
WBC: 20/hpf
Bacterial: > 100,000 cfu / E. coli pan-sensitive

What is the best next step in management? Review Topic

QID: 109565
1

Observation and treatment if symptoms develop

0%

(0/40)

2

Nitrofurantoin for seven days

92%

(37/40)

3

Observation and repeat cultures in one week

2%

(1/40)

4

Nitrofurantoin for duration of pregnancy

2%

(1/40)

5

Levofloxacin for three days

2%

(1/40)

M2

Select Answer to see Preferred Response

PREFERRED RESPONSE 2

(M2.OB.4672) A 32-year-old G3P2 at 20 weeks gestation presents to her PCP with complaints of fatigue, chills, and decreased appetite for the past 5 days. Her pregnancy has been uncomplicated to-date, and she has been receiving regular prenatal care. The patient mentions that, in an attempt to increase nutrition for her fetus, she has been consuming increased amounts of dairy products in the past month. At 35 weeks gestation, the patient delivers an ill neonate with sepsis, pneumonia, and disseminated skin findings (Figure A). What is the appropriate action that the PCP should have taken after the patient’s initial presentation? Review Topic

QID: 107192
FIGURES:
1

Supportive care with rest and hydration

0%

(0/17)

2

Blood and amniotic fluid cultures

24%

(4/17)

3

Vaginal and stool cultures

29%

(5/17)

4

Empiric ceftriaxone therapy

12%

(2/17)

5

Empiric ampicillin therapy

29%

(5/17)

M2

Select Answer to see Preferred Response

PREFERRED RESPONSE 2

(M2.OB.4672) A 33-year-old G1P0 at 32 weeks gestation presents to her OB/GYN for a prenatal check-up. Her medical history is significant for type II pregestational diabetes mellitus, which has been well-controlled with diet and insulin so far throughout her pregnancy. Which of the following is the recommended future follow-up for this patient? Review Topic

QID: 107200
1

Ultrasound for fetal growth every week starting now until delivery

27%

(6/22)

2

Monitor fetal kick counts starting now until 40 weeks gestation

9%

(2/22)

3

Monthly nonstress test strating at 34 weeks gestation until delivery

5%

(1/22)

4

Monthly biophysical profile now until delivery

14%

(3/22)

5

Twice weekly nonstress test now until delivery

41%

(9/22)

M2

Select Answer to see Preferred Response

PREFERRED RESPONSE 5

(M2.OB.4672) A 27-year-old G0P0 female presents to her OB/GYN for a preconception visit to seek advice before becoming pregnant. A detailed history reveals no prior medical or surgical history, and she appears to be in good health currently. Her vaccination history is up-to-date. She denies tobacco or recreational drug use and admits to drinking 2 glasses of wine per week. She states that she is looking to start trying to become pregnant within the next month, hopefully by the end of January. Which of the following is NOT recommended as a next step for this patient's preconception care? Review Topic

QID: 107199
1

Begin 400 mcg folic acid supplementation

8%

(6/73)

2

Recommend inactivated influenza vaccination

3%

(2/73)

3

Obtain rubella titer

1%

(1/73)

4

Administer measles, mumps, rubella (MMR) vaccination

78%

(57/73)

5

Obtain varicella zoster titer

8%

(6/73)

M2

Select Answer to see Preferred Response

PREFERRED RESPONSE 4
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