MS3 Medical Complications in Pregnancy

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jknell
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206931
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MS3 Medical Complications in Pregnancy
Updated:
2013-03-13 14:43:42
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Multisystem Disorders
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Multisystem Disorders
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  1. Progesterone
    "Pro-gestation" hormone

    • Synthesis:
    • -corpus luteum of ovary (rescued by hCG if fertilzation occurs)
    • -placenta during pregnancy (syncytiotrophoblast)
    • -synthesized from maternal cholesterol (LDL)

    • Functions:
    • -suppress myometrial activity
    • -relax smooth muscle
    • -increase sensitivity to CO2
    • -immunomodulation
    • -increase Na+ and Cl- excretion
    • -substrate for fetal adrenal steroids
  2. Estrogens
    • Estrone
    • Estradiol
    • Estriol
    • Estetrol

    • Synthesis:
    • 1. Androgen precursors
    • -Fetal and maternal adrenal DHEA-S (estrone, estradiol)
    • -Fetal 16a-OH-DHEA-S (estriol)
    • 2. Placental sulfatase, aromatase

    • Maternal Effects:
    • -increases uterine blood flow
    • -increases hepatic production (binding proteins, coagulation factors)
    • -stimulates RAAS (increased aldosterone)
    • -sensitize uterus to labor
  3. Human Chorionic Gonadotropin (hCG)
    • The "pregnancy horomone"
    • -detectable at day 21 of cycle
    • -doubling time 31 hours (sign of viability)

    • Dimeric protein
    • -a unit (TSH, LH, FSH)
    • -thyrotropic
    • -b unit (LH)

    • Function:
    • -luteotropin (maintains CL)
    • -essential day 1 to week 10
    • -fetal testes, adrenal (androgen, corticosteroid production)
    • -immunomodulation (suppresses decidual T cells)
  4. Chorionic Somatomammotropin (hCS)
    • aka: Placental Lactogen (hPL)
    • -homology to hGH and prolactin
    • -detected by day 21 (rapid half life, 1-4g produced per day)

    • Function:
    • -modify maternal metabolism
    • -insulin agonist (GH-like) (increase available glucose, increase insulin, increase lipolysis and FFA)
    • -minimal lactogenic or growth activity
    • -non-essential
  5. Cardiovascular Adaptations
    • Critically important
    • -delivery of oxygen and substrates to fetus
    • -removal of fetal waste

    • Uterine blood flow augmented 10-fold
    • -increased flow and vascular capacitance

    • Changes are rapid, substantial and reversible
    • -present in the first weeks of pregnancy
    • -plateau at 28-32 weeks
    • -augmented in labor
    • -generally resolve by 6 weeks postpartum
  6. Blood Volume
    • Increased by 40-50%
    • -begins by 4th menstrual week
    • -wide individual variation
    • -peak at 28-34 weeks

    Greater increase with multiples

    Failed expansion threatens fetal growth



    • -most of the expansion is due to increased plasma volume
    • -can lead to anemia

    Return to non-pregnant levels by six weeks postpartum
  7. Plasma Volume
    • Accounts for 3/4 of increased TBV
    • -40% average increase
    • -1.2-1.6L by 28 weeks

    • Mediated by:
    • 1. Sodium Retention and Volume Expansion
    • -RAAS
    • -changed "osmostat"
    • 2. Vasodilation
    • -estrogen - NO system
    • -progesterone effect on venous tone
    • -vasodilating prostaglandins
  8. Cardiac Output
    • 30-50% Increase
    • -from 5 to 7 L/min
    • -half happens by 8 weeks
    • -plateau at 20 weeks
    • -sustained until delivery

    • Mediated by:
    • 1. Rapid increase in SV (due to preload, blood volume)
    • 2. Progressive rise in heart rate
    • 3. Utero-placental shunt (reduced resistance)
  9. Systemic Vascular Resistance
    • Rapid decrease in SVR
    • -nadir 14-24 weeks
    • -slow increase until term

    • Mediated by:
    • 1. Progesterone
    • -smooth muscle relaxation (angiotensin resistance)
    • 2. Estrogens
    • -endothelial products (prostacyclin, NO)
    • 3. Compliance Changes
    • -collagen remodeling
    • 4. Utero-Placental shunt
  10. Blood Pressure
    • Decreased BP
    • -DBP > SBP
    • -nadir 24-32 weeks
    • -normalized at term

    • Mediated by:
    • -vasodilation (NO, Prostacyclin, estradiol)
    • -Shunt
  11. Regional Blood Flow
    • Uterus
    • -10 fold increase (from 50 to > 500 mL/min)
    • -10-20% of CO

    • Breasts
    • -increased flow

    • Renal
    • -50-80% increase
    • -% of CO stable
    • -for waste excretion

    • Skin
    • -heat dissipation
    • -mucous congestion

    • Pulmonary
    • -vascular markings on CSR
  12. Cardiovascular Exam Findings
    Increased silhouette, enlarged atria

    • EKG:
    • -rotation of QRS axis, R axis deviation
    • -ST segment depression
    • -Q waves in III-T wave inversion in III
    • -normal rate (NOT tachycardic)

    PMI elevated to left

    Pulse brisk and full

    JVP distention, venous hum

    • Heart Sounds:
    • -early to mid systolic flow murmur
    • -loud and widely split S1
    • -S3 murmur

    • Skin Vessels:
    • -spider angiomas
    • -varicose veins

    • Vascular Permeability
    • -dependent edeam
  13. Clinical Implications of Cardiovascular Changes
    • Common Symptoms:
    • -fatigue
    • -dyspnea
    • -orthopnea
    • -pre-syncope
    • -dizziness
    • -palpitations
    • -edema

    • Cardiovascular Disease in Pregnancy
    • 1. Pregnancy Poorly Tolerated
    • -pulmonary hypertension
    • -Marfans Syndrome
    • -Aortic Coarctation
    • *high risk for decompensation, often recommend that they not get pregnant
    • 2. Moderate Risk
    • -Aortic stenosis
    • -Mitral stenosis
    • -Prosthetic valves
    • -Myocardial infarction

    • 3. Low Risk
    • -VSD-ASD
    • -Corrected Tetralogy of Fallot
    • -Ductus arteriosus
  14. Mitral Valve Stenosis in Pregnancy
    -about 60% with moderate to severe stenosis become symptomatic by 30 weeks (at the peak of vascular volume increase)

    -critical to control heart rate to preserve stroke volume

    -risk of thromboembolism with enlarging left atrium, especially with atrial fibrillation

    -monitor volume status closely (need preload but careful not to push into pulmonary edema)

    -want to control pain (can push into decompensation)

    -hospitalize for up to one week after delivery b/c risk is still elevated at this time
  15. Respiratory Adaptations
    • Anatomic Changes:
    • -diaphragm higher (by 10 weeks so not just due to gravid uterus)
    • -thorax rounder
    • -ribs elevated

    • Mediators:
    • 1. Progesterone
    • -stimulates respiration (increased CO2 sensitivity, increased ventilatory drive)
    • -bronchodilation
    • 2. Prostaglandin PGE1, PGE2
    • -bronchodilators

    • Overventilation is beneficial for fetus
    • -favors O2 delivery to fetus
  16. Lung Volumes in Pregnancy
    • TLC: small decrease due to elevation of diaphragm

    • TV: increases 30-40%
    • -long inhalations and exhalations
    • -at the expense of ERV

    FRC, ERV and RV decrease

    *Pregnant women have a lower reserve and are at increased risk for hypoxia
  17. Clinical Implications of Respiratory Changes
    • Gradients facilitate transplacental exchange
    • -removal of CO2 and acids
    • -delivery of O2

    • Symptoms:
    • -dsypnea (60-70%)
    • -congestion, rhinitis
    • -epistaxis

    • Diseases and Exposures:
    • -pulmonary edema
    • -asthma
    • -smoking
    • -pneumonia and respiratory failure
  18. Asthma in Pregnancy
    -Unpredictable: improve, no change or worse

    • Factors influencing improvement:
    • -increase circulating free cortisol
    • -decrease bronchomotor tone and airway resistance
    • -increase serum cAMP levels

    • Factors influencing worse disease:
    • -exposure to fetal antigens
    • -alterations in cell-mediated immunity
    • -hyperventilation

    Severe asthma before = severe asthma in pregnancy
  19. Respiratory Treatment Goals in Pregnancy
    • -prevent allergen exposure
    • -treat sinusitis, bronchitis
    • -avoid strenuous exercise/exposure to cold
    • -treat reflux to prevent bronchospasm
    • -stop smoking
    • -low threshold for oral steroids at onset of URI
    • -MDI treatment plan
  20. Acid-Base Status in Pregnancy


    Hyperventilation causes alkalosis

    Fetus can handle low PO2 due to HbF

    Fetal umbilical vein contains oxygenated blood
  21. Hematologic Adaptations
    • Anemia of pregnancy:
    • -primary dilutional (third trimester catch up)
    • -increased RBC mass (increased Epo)
    • -iron deficiency (33% decrease in maternal Fe)
    • -fetus can also be affected by iron deficiency (often supplement)

    Leukocytosis

    Thrombocytopenia
  22. Hemostatic Adaptations
    • Thrombophilic state of pregnancy
    • -increased coagulation factors (fibrinogen, VII, VIII, X, vWF)
    • -increase contact factors (XII, HMWK, prekallikrein)
    • -increase fibrinolytic inhibitors (PAI-1, PAI-2)
    • -decrease anticoagulation factors (protein S, protein C)

    • Clinical Implications:
    • -10 fold risk of VTE
    • -but provides improved hemostasis at delivery
  23. Diagnosis of PE in Pregnancy
    • V/Q scan
    • -safe

    • CT scan
    • -dose and timing
    • -first trimester

    Angiogram

    Lower extremity U/S

    D-dimer
  24. Anticoagulation in Pregnancy
    • Coumadin
    • -known teratogen
    • -can be prescribed for breast feeding women

    • Levonox
    • -can be given til 36 weeks, then heparin

    Delivery planning

    Resume anticoagulation post partum through 6 weeks
  25. Thyroid Axis Adaptations
    • Euthyroid hyperthyroxinemia
    • -hCG stimulates the thyroid
    • -estrogen increases thyroid binding globulin
    • -increase total T3 and T4
    • -slight increase in free T3 and T4
    • -slight decrease in TSH
    • -increase thyroid hormone 40-100%



    • Maternal Thyroid
    • -gland hypertrophy
    • -increase renal excretion of iodine (need supplementation)
    • -check TSH and free T4 to assess thyroid function in pregnacy

    • Fetal Thyroid:
    • -no organic iodide until 10 weeks
    • -produce T3 and T4 by 11-12 weeks
    • -mature levels of TSH, T4, free T4 by 12 weeks

    • Crossing Placenta
    • -iodide
    • -T4
    • -thyroid stimulating Abs
    • -TRH
    • -methimazole and PTU
    • ***TSH does NOT cross
  26. Clinical Implications of Thyroid Changes
    • Thyroid disorders → symptom mimicry
    • -difficult to distinguish normal pregnancy from disease
    • -lab changes (total T4 unreliable)
  27. Hyperthyroidism in Pregnancy
    Radioactive iodine contraindicated

    • Thyrotoxicosis → Thyroid Storm
    • -high mortality rate if untreated
    • -hyperthermia, tachycardia, perspiration, high output failure or dehydration
    • -goal to lower HR, temperature, replace fluid losses, block secretion and synthesis of thyroid hormone

    • Medical Treatment
    • -PTU first line
    • -methimazole (more concern about use in first trimester)
    • ***both cross placenta so monitor monthly TFTs

  28. Hypothyroidism in Pregnancy
    • Untreated hypothyroidism
    • -increased risk for spontaneous abortion, low birth weight, stillbirth, decreased IQ
    • -fetal thyroid deficiency during first and secondy trimester can lead to generalized developmental retardation
    • -congenitaly hypothyroidism 1/4000

    • Diagnosis:
    • -elevated TSH
    • -low free T4

    • Treatment:
    • -replace with levothyroxine and monitor monthly

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