Obstetrics

     

    Pre-conception

    • Folic acid 3mo prior to conception reduces risk of open neural tube defects by 70%
      • 0.4mg daily for first 3mo after conception
      • 5mg if epilepsy, family history of neural tube defects or previous history of NTD, or BMI >35
    • Replace drugs to safe-in-pregnancy.  Some notable ones:
      • HTN:
        • Safe: Nifedipine, labetolol, methyldopa
        • Unsafe: ACEi, 
      • Anticoagulation
        • Safe: Heparin, LMWH
        • Unsafe: warfarin (warfarin embryopathy)

    Diagnosis

    Presumptive Signs

    • Amenorrhea
    • Chadwick's sign (discoloration of walls of vagina+ cervix due to increased vascularity)
    • Breast changes: darkening of areolae, Montgomery's follicles (tubercles), prominent vascular patterns
    • Subjective: fatigue, urinary frequency, GI (N/V, const, dyspepsia)
    • Abrominal/Breast striae
     

    Probable Signs

    • Enlargement of abdomen
    • Enlargement of uterus
    • Softening of cervix (Hegar's sign)

    Positive Signs

    • Ausc of fetal heart
    • Perception of fetal movement by examiner
    • USS
    • B-HCG
      • Serum positive 9days post conception (doubles q48h to max at 8-10weeks)
      • If rising slower --> missed abortion or ectopic pregnancy
      • If rising faster --> multiple pregnancy or molar

    Schedule of Care

     
    Weeks  Care
    8-12 weeks First Visit
    Visit q4weeks until 28 weeks
    Visit q2weeks until 36 weeks
    Visit q1week until delivery
    11-14w IPS Part I or FTS if desired
    15-20w IPS part II or Maternal Serum alphafetoprotein, or quad screen
     27-29w Glucose Challenge Test, Rh immune globulin (Rhig or Rhogam) for Rh- pts.  Repeat CBC
     36w Vaginorectal swap for GBS, Repeat CBC
     40+ Weekly BPP for post-dates
     

    First Antenatal Visit

    • Blood work:
      • CBC
      • Rubella IgG, Varicella (ask if had it, but if non-Canada then still check titre), HepB Surface Antigen and
      • surface+core Ab (do HepE if HepB positive, often co-occur), VDRL, HIV
      • Blood Group + Rh Status + Antibody Screen (check for red cell antibodies)
      • TSH (sometimes, often wait until 28 wks with OCTT, as early TSH often depressed)
        • if Already hypothyroid:
          • Target TSH = 2 (30% increase requirement, may need to double medications)
          • Recheck in 2 weeks.
      • Screen Sickle Cell Disease + screen partner if positive.
      • Ashkenazi Jews: (tay sacs disease)
      • Pavrovirus B19 - small child at home, teachers, healthcare workers
    • Pelvic Exam:
      • Pap smear
      • Cervical cultures for Gonorrhea and Chlamydia
    • Urinalysis
      • R&M + C&S (2-7% of women have asymptomatic bacteuria)

     

    Assessment of Fetus

    • U/S:
      • 5 weeks: intrauterine sac
      • 6 weeks: fetal pole
      • 7-8 weeks: fetal cardiac activity
    • Perception of fetal movement by examiner

    Genetic Testing

       Trisomy 21  Trisomy 18  ONTD
    MSAFP  Decreased  Decreased  Increased
    HCG  Increased  Decreased  
    Estriol  Decreased  Decreased  
    - Twins higher risk of chromosomal abnormality
    - FTS/IPS/Quad Screen not applicable to twins (use Nuchal Translucency NT)
    - MSS-AFP can be used to screen ONTD in twins.
     
    down syndrome risk.gif

    First Trimester Screen (FTS)

    • Assesses risk of Down Syndrome (Trisomy 21 and 18), NOT ONTD (Open Neural Tube Defects)
    • 11 4/7 - 14 1/7 GA (accurate dating important)
    • Assessment:
      • Fetal nuchal translucency in mm
      • Serum B-HCG
      • Serum PAPP-A (pregnancy associated plasma protein A)
    • Sensitivity 85%, FP rate 5%
    • Old screen, gives earlier results, but less sensitivity and specificity

    Integrated Prenatal Screening (IPS)

    • Part A: FTS (ultrasound + blood test), but results withheld until complete:
    • Part B: Also 2nd trimester (15+1, 19+6) blood test AFP, BhCG, estriol (uE3)
    • Sensitivity 90%, FP rate 3%
    • Reports on T21, T18, and ONTD (Open Neural Tube Defects)
    • New Screen designed to improve sensitivity/specificity, but gives results later (most common)

    Quad Screen

    • Blood test, GA 15+1 to 20+6
    • Risk of chromosomal abn (T18, T21) and ONTD
    • Sensitivity: 70%, FP rate 5-7%
    • Includes (AFP, BhCG, estriol (u3), inhibin A)
    • Not done anymore - just all the blood tests combined

    Chorionic Villus Sampling (CVS)

    • At 11-14 weeks
    • Placental biopsy via transcervical or transabdominal
    • uses FISH and QF-PCR
    • 1-2% pregnancy loss
    • Slightly higher rate of cell culture loss than amniocentesis (also sometimes placental mosaicism)

    Amniocentesis

    • GA after 15wks (normally 15-20)
    • Get amniotic fluid transabdominally under U/S guidance.
    • Karyotype (FISH+PCR in 2-3 days, and karyotype 2-3 weeks)
    • Pregnancy loss 0.5%, recent FASTER trial: much lower.

    Determining Gestation Age (GA)

    • Estimated Date of Confinement (EDC)by Haegle's rule:
      • LMP + 9mo + 7 days or:
      • LMP - 3mo + 7 days
      • Based on 28-30day cycle, adjust based on length
    • Gestational wheel
    • Ultrasound (accurate within 1 week, less accuracy with incr age)
    • Bimanual/Abdo exam:
      • Symphysis-fundal height: cm=wks (btwn 20-36wks)
      • Fundus at symphysis at 12 weeks (via bimanual exam)
      • Fundus btwn symphysis and umbilicus at 16 weeks
      • Fundus btwn at umbilicus at 20 weeks
      • Fundus at xyphoid at term

    Drugs and Pregnancy

        Contraindicated
    • ACE inhibitors: IUGR, oligohydraminos, renal defects (renal teratogen)
    • Tetracycline: stains teeth, long bone development
    • Retinoids (Accutane): Major teratogen (craniofacial, cardiac, thymic, CNS malformations)
    • Diethylstilbesterol (DES): [synthetic estrogen] historic risk, female gental tract structural carcinoma, clear cell carcinoma
     
        Weight Risks vs Benefits of:
    • Anticonvulsants
    • Lithium (Ebstein's anomaly)
    • Coumadin: warfarin embryopathy (nasal hypoplasia, epiphyseal stippling, optic atrophy, intra-cranial bleeds)  - use heparin
    • Quinolones: Category C: but not enough information.  It appears high doses do not cause birth defects in animal studies.  May cause slightly increase risk of miscarriage in rabbits.  May increase risk of birth defects in some studies, but no pattern.  Never studied on humans.  Hence, very controversial. 
    • SSRIs:
      • Investigated risk of anencephaly, craniosynostosis, amphalocele, possible ASD/VSD, but absolute risk of extremely small anyways
      • Neonatal Abstinence Syndrome (withdrawal) and Persistent Pulmonary Hypertension of Newborn (PPHN) (6-12/1000 exposed)
      • Paxil (paroxetine) not recommended

     

    Nausea and Vomiting of Pregnancy (NVP)

    • aka "morning sickness" misnomer, have it all day.
    • Persistent vomiting
    • Most severe form "Hyperemesis gravidarum" occurs in 1%
    • Worse in 1st trimester, but can persist throughout pregnancy
    • affects 1% of pregnancies
    • Tx:
      • Avoid mixing fluids/solids, small meals, stop vitamin, increase sleep (fatigue can exacerbate)
      • Diclectin (Doxylamine/pyridoxine) Class A, no risk.  Start 2-4 tablets daily, increase to 8 as needed
        • Doxylamine: sedating antihistamine
        • Pyridoxine: vitamin B6
      • Can add dimenhydrinate 50-100mg q5-6h po or pr.
      • If dehydrated, rehydrate, correct electrolyte abnormalities
      • SEE SOGC ALGORITHM

    Miscarriage (Spontaneous Abortion)

    • Conselling:
      • 1/5 women (or 1/6) have this happen
      • 1.  There is nothing you could have done to prevent this.
      • 2.  There is nothing you could have done to cause this.
      • 3.  It is nature's way
      • It does not increase chances of subsequent SA

    Early Pregnancy Bleed

    • Ddx:
      • Ectopic Pregnancy (1.7%)
      • Spontaneous Abortion (15% at 20yo, 40% at 40).
      • Implantation bleed (normal)
      • Uterine pathology: polyps, fibroids
      • Cervical pathology: cervical ca, or friable cervix post-coital
      • Vaginal pathology: vaginal tumors, trauma.
    • Management:
      • 1.  CBC 
      • 2.  Group & Screen +/- Rhogam
      • 3.  B-HCG
      • 4.  TVUS
     

    TORCH

    • Infectious that can cross placenta to fetus
      • T - Toxoplasma
        • Hepatosplenomegaly
        • Hydrocephalus
        • Chorioretinitis
        • Intracranial calcifications
      • O - Other
      • R - Rubella  (Congenital Rubella)
        • Sensorineral hearing loss
        • Cataracts
        • Heart Defects
        • Hepatosplenomegaly
        • Mecrocephaly
        • Thrombocytopenic purpura (blueberry muffin rash)
      • C - CMV
        • Intrauterine growth retardation
        • hepatosplenomegaly
        • Petechiae/purpura
        • microcephaly
        • chorioretinitis
        • sensorineural hearing loss
        • Periventricular calcifications
      • H - HSV-2
    • TORCH infections characterized by:
      • Growth retardation
      • Microcephaly
      • Chorioretinitis
      • Hepatosplenomegaly
      • Deafness
      • Thrombocytopenia
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