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Special Guest

Janelle Bludorn, MS, PA-C is faculty at the University of North Carolina School of Medicine Physician Assistant Program as a clinical assistant professor with extensive practice history in academic emergency medicine and women’s health.  She is active on social media and you can find her on Twitter @JanelleRBlu and her website http://janellebludorn.com/.

Definition of the 1st Trimester

The 1^st trimester of pregnancy is from conception to week 12 gestation.  It is important to note that most women do not even think about the possibility of pregnancy until 2-3 weeks post-conception and is typically after a week as passed without the initiation of a menstrual cycle.  This can become even more difficult if a woman has baseline irregular menses, or the fact that early pregnancy bleeding is can occur in up to 10% of women.

Physiological Changes of Pregnancy in 1^st Trimester

• Cardiovascular
  • Systemic vasodilation
  • Increased plasma volume > change in RBC mass
  • Increased resting heart rate
• Pulmonary
  • Elevation of diaphragm
  • Decreased functional residual capacity
  • Increased ventilation and respiratory drive
• Gastrointestinal
  • Hypomotility of bowel and gastroparesis
• Renal
  • GFR increases
  • BUN/Cr decreases

Signs and Symptoms of Early Pregnancy

60% of women may experience these symptoms within 6 weeks of conception and 90% will experience by 8 weeks:

• Amenorrhea
• Nausea and vomiting
• Breast enlargement and tenderness
• Increased frequency of urination without dysuria
• Fatigue
• Abdominal bloating
• Shortness of breath
• Lightheadedness
• Back pain

Physical Examination

• The uterus remains a pelvic organ until around 12 weeks gestation
• Cervix may soften (Goodell’s sign) and have a bluish color from vascular congestion (Chadwick’s sign)
• Breast become fuller, tender, and hyperpigmentation of the areola may occur
• Fetal cardiac activity can be picked up by transvaginal ultrasound as early as 6 weeks, but fetal heart tones won’t be heard until 10-12 weeks by handheld doppler

Diagnosis of Pregnancy

There are 2 ways to diagnosis pregnancy:

• Laboratory
  • Detection of human chorionic gonadotropin (hCG)
    • Urine (threshold – 20-50 milli-IU/mL)
      • Can be detected as early as 2 weeks from fertilization
    • Blood (threshold – 2-10 millil-IU/mL)
      • Significantly more sensitive than urine and can be positive with a negative urine test
• Radiographically by ultrasound
  • Gestational sac or intrauterine fluid collection may be visible at 4-5 weeks gestation
  • Yolk sac appears at 5-6 weeks gestation and remains until 10 weeks
  • Fetal pole with cardiac activity can be detected at 5-6 weeks (if transvaginal, closer to 6-7 weeks if transabdominal)

Errors in Laboratory Testing

• False Negatives
  • Testing too soon after conception
  • Hook effect
    • Extremely high hCG and not diluted by lab
• False Positive
  • Biochemical pregnancy
    • Early fetal loss with elevated circulating hCG
  • hCG from trophoblastic disease

Goals of Prenatal Care

The initial visit should occur in the 1^st trimester (ideally by 10 weeks), but only 60-75% of women achieve this.

Clinical/Provider

• Early, accurate estimation of gestational age
• Identification of high risk mothers
• Ongoing evaluation of maternal and fetal health status
• Anticipatory guidance and health promotion

Mother/Patient

• Maintaining normality
• Ensuring healthy pregnancy
• Planning for effective labor and delivery
• Achieving positive motherhood transition

Components of Initial Prenatal Visit

• History
  • Medical/Obstetrical
    • Personal/demographic information
      • Age, hospital preference, post-delivery contraception
    • Past obstetrical history
      • Prior pregnancies and outcomes
      • Complications
      • Weight and health of infants
      • Any surgical obstetric history
    • Family History
      • History of dystocia
      • History of hemorrhage
      • Bleeding disorders
    • Past Surgical History
    • Menstrual/Gynecological history
    • Recent travel
    • Social History
      • Tobacco, EtOH, illicit drug use
    • Sexual History
      • Exposure to STI
    • Psychosocial
      • Planned/unintended pregnancy
      • Partner involvement
      • Parenting plan
      • Potential barriers to care
        • Communication, transportation, child care, economic
      • Housing
      • Baseline mental health
      • Screening for intimate partner violence
  • Calculation of Gestational Age
    • Naegle’s Rule
      • (((1^st day of the LMP) – 3 months) + 7 days) + 1 year
      • 
    • MedCalc: Pregnancy Due-Dates Calculator
    • 
  • Physical Examination
    • Physical Examination
      • Blood pressure, height, and weight should be recorded
  • Ultrasound Examination
    • Generally not indicated unless:
      • Irregular menstrual cycles
      • LMP is unknown
      • Conception in spite of contraception
      • Uterine size discordant with menstrual dates
      • ACOG recommendation – optimal timing of screening ultrasound examination is 18-22 weeks gestation.
  • Aneuploidy Screening (usually between 16-20 weeks)
    • ACOG recommends:
      • All women be offered screening before 20 weeks gestation
      • All women have the option of diagnostic invasive procedure instead of screening
      • Both of these are regardless of maternal age
    • 2 main categories of testing
      • Maternal serum levels of biochemical markers
      • Cell-free DNA in maternal circulation
    • 
  • Laboratory Screening
    • Rhesus type and antibody screen
      • Rh(D)-negative women should receive prophylactic anti(D)-immune globulin at 28 weeks
    • CBC
    • Urine protein
    • Urine culture
    • Cervical cancer screening
    • Infectious Disease
      • HIV testing
      • Documentation of rubella immunity (rubella antibody)
      • Documentation of varicella immunity (varicella antibody)
      • Syphilis (RPR)
      • Hepatitis B (surface antigen)
      • Gonorrhea and Chlamydia
    • Thyroid function (TSH)
  • Anticipatory Guidance
    • Nutrition
      • 300 kcal/day
      • 3-6lbs in 1^st trimester depending on BMI
    • Exercise
      • Moderate is best
    • Coitus
      • Safe until 1-2 weeks before delivery
    • GI Complaints
      • Nausea
        • Small, frequent meals
        • Vitamin B6 + doxylamine (Diclectin)
      • GERD
        • Small, frequent meals
        • H2-blockers and PPI safe
      • Constipation
        • Stool softeners safe
      • Back pain
        • Stretching, acetaminophen, heating pads

Common Complications of 1^st Trimester

• Vaginal bleeding
  • 20-40%
  • Work-up
    • Abdominal/GU physicial examination
    • Serum b-hCG
    • Transvaginal ultrasound{…}
• Nausea and Vomiting
  • 50-75% with 1:200 women developing hyperemesis gravidarum
  • Work-up
    • BMP, CBC, urinalysis
      • Concerned for dehydration and ketosis
• Ectopic Pregnancy
  • 2% of all pregnancy
  • Risk Factors
    • Prior tubal injury
      • Tubal surgery, prior ectopic, genital tract infection
    • Work-up
      • Transvaginal ultrasound
• Gestational Trophoblastic Disease
  • 4 types
    • Hydatidiform mole
    • Invasive mole
    • Choriocarcinoma
    • Placental trophoblastic tumor
  • Work-up
    • Serum b-hCG
      • Hallmark is EXTREMELY elevated levels
    • Transvaginal ultrasound
      • Hallmark is “snowstorm appearance”

Time Line for Subsequent Prenatal Visits

• Every 4 weeks until 28 weeks gestation
• Every 2 weeks until 36 weeks gestation
• Every week until delivery

References

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3. Foxcroft KF, Callaway LK, Byrne NM, Webster J. Development and validation of a pregnancy symptoms inventory. BMC pregnancy and childbirth. 2013; 13:3. [pubmed]
4. Lohstroh P, Dong H, Chen J, Gee N, Xu X, Lasley B. Daily immunoactive and bioactive human chorionic gonadotropin profiles in periimplantation urine samples. Biology of reproduction. 2006; 75(1):24-33. [pubmed]
5. Furtado LV, Lehman CM, Thompson C, Grenache DG. Should the qualitative serum pregnancy test be considered obsolete? American journal of clinical pathology. 2012; 137(2):194-202. [pubmed]
6. Early Pregnancy.  https://radiopaedia.org/articles/early-pregnancy
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8. ACOG Committee Opinion No. 343: psychosocial risk factors: perinatal screening and intervention. Obstetrics and gynecology. 2006; 108(2):469-77. [pubmed]
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13. Doubilet PM, Benson CB, Bourne T. Diagnostic criteria for nonviable pregnancy early in the first trimester. NEJM. 2013; 369(15):1443-51. [pubmed]
14. ACOG. Practice Bulletin No. 175: Ultrasound in Pregnancy. Obstetrics and gynecology. 2016; 128(6):e241-e256. [pubmed]