questions 13

Prenatal Care

Topic updated on 10/25/17 5:52pm

  • Symptoms of pregnancy
    • amenorrhea
    • urine frequency
    • breast engorgement
    • 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
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
  • 17 weeks 
    • document movement
    • amniocentesis if > 35 years old or history indicates
  • 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


Qbank (4 Questions)

(M3.OB.5) A 19-year-old woman presents to her gynecologist with amenorrhea. Beta-HCG is positive, and she is estimated to be 16 weeks pregnant by last menstrual period and ultrasound. This is her first pregnancy. The patient has a BMI of 23 and no chronic medical conditions. For which of the following conditions or characteristics should the patient be screened as standard prenatal care at this time? Topic Review Topic

1. HIV, syphilis, and hepatitis C
2. Gonorrhea, chlamydia, and human papilloma virus
3. Toxoplasmosis, rubella, cytomegalovirus, herpes simplex virus, syphilis
4. Anemia, Rh incompatibility, and hyperglycemia
5. Hepatitis B, urinary tract infections, and blood type

(M3.OB.27) A 25-year-old nulliparous woman presents to the clinic for her first prenatal visit. Which of the following risk factors warrants syphilis screening in this patient? Topic Review Topic

1. History of gonococcal urethritis
2. History of HIV
3. History of abnormal Pap smear
4. History of autoimmune disease
5. All pregnant women should be screened for syphilis

(M2.OB.22) A 31-year-old G3P2 presents for a first-trimester prenatal visit. You perform the standard first-visit tests including blood type and screen, Rh type, CBC, immunization status, urinalysis for protein, and Pap smear. Which of the following first-visit tests will you also administer in the third trimester? Topic Review Topic

1. HIV
2. Rubella
3. Hepatitis B and C
4. Urinalysis
5. Pap smear

(M2.OB.111) A 30-year-old G3P2 woman presents for her first prenatal visit following a positive home pregnancy test. Past medical history is notable for hypothyroidism. You inform her that if she is pregnant she will have to increase her dose of levothyroxine. Which of the following best explains why the dose of levothyroxine is increased in pregnant women?
Topic Review Topic

1. Cytochrome P-450 activation
2. Increased thyroxine-binding globulin (TBG) levels
3. Decreased TSH production
4. Decreased oral bioavailability of levothyroxine
5. Increased responsiveness of the anterior pituitary to circulating free T4

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