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6. HDS GI Repro > Normal Pregnancy > Flashcards

Normal Pregnancy Flashcards

1
Q

Fertilization

A

Intercourse must occur prior to ovulation for successful fertilization to occur.

  • Egg released from ovary in metaphase II surrounded by cumulus oophorus (granulosa cells) and zona pellucida
  • At the same time sperm is moving through cervical mucus and uterus
  • Sperm undergoes capitation and acrosome reaction
  • Sperm and egg meet in the ampulla of the fallopian tube
  • Sperm passes the zona pellucida, attaches to the cell membrane and enters the cytoplasm
  • Completion of a second meiotic division ⇒ male and female pronucleus (haploid set of chromosomes)
  • Nuclear membrane disappears and diploid set of chromosomes is reestablished
  • Once the zygote is formed the cells will continue to divide
    • Division allows for the potential for twinning
    • Twinning may occur at any stage until the formation of the blastula
    • Occurs by the separation of the two cells produced by cleavage
    • Each cell has the potential to develop into an embryo
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2
Q

Types of Twins

A
  • Diamniotic/dichorionic: prior to 3 days post fertilization
  • Diamniotic/monochorionic: 4-8 days post fertilization
  • Monoamniotic/monochorionic: 9-12 days post fertilization
  • Conjoined: 12 days or more post fertilization

The embryo continues to divide as it travels through the fallopian tube

Enters the uterus in 3-4 days after fertilization

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3
Q

Implantation

A
  • Implantation can be as early as 6 days after fertilization
  • Usually 3 days after embryo enters the uterus
  • zona pellucida must be removed prior to implantation
  • Endometrial capillaries come in contact w/ invading syncytiotrophoblasts ⇒ engulfed to form venous sinuses (generally 7.5 days after conception)
  • ER of the syncytiotrophoblasts is responsible for production of human chorionic gonadotropin (HCG)
  • HCG enters maternal circulation ⇒ corpus luteum maintained
  • Corpus luteum maintains pregnancy until the placenta takes over
  • Progesterone is steroid of greatest importance in maintaining pregnancy
  • After 7 wks, placenta becomes the dominate place for steroid production
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4
Q

Embryology

A
  • Embryonic period is the first 49 days after conception
    • Organogenesis is complete at this time
  • Effects of Teratogens:
    • Susceptibility to a teratogen depends on:
    • Genotype of the conceptus
    • Manner in which genotype interacts w/ environmental factors
    • Developmental stage at the time of exposure
  • Wks 2-8 is when most structural defects occur
  • Teratogens act by different mechanisms
    • Alter normal cellular or biochemical processes
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5
Q

Maternal Cardiovascular Changes

A

Earliest and most dramatic changes

Changes are to improve the fetal oxygenation and nutrition

  • Anatomic changes:
    • Heart displaced upward and to the left
    • Assumes more horizontal position
      • Result of diaphragmatic elevation from displacement of abdl viscera by expanding uterus
    • ↑ Ventricular mass
    • ↑ LV and LA size d/t ↑ Circulating blood volume
  • Functional changes:
    • 1° functional change is ↑ cardiac output (CO)
      • Overall CO ↑ 30-50%
        • ↑ 50% by 8 wks
      • Relative ↓ blood flow→ splanchnic and skeletal muscle (absolute amount ↔︎)
      • 20% of CO (750cc/min) →uterus at term
      • First half of pregnancy
      • ↑ Stroke volume ⇒ ↑ CO
        • ∆ SV d/t ∆ circulating blood volume (peak ↑ at 32 wks) and systemic vascular resistance
        • ↑ Progesterone ⇒ ↓ SVR
          • ↓ Smooth muscle tone and AV shunting to uteroplacental circulation
          • ↑ Vasodilatory substances (progesterone, NO, and ANP)
      • Second half of pregnancy
        • ↑ HR and SV returns to nl ⇒ ↑ CO
    • Blood pressure
      • ↓ Through 2nd trimester
      • Normalizes toward the end of pregnancy
    • Pulse
      • ↑ Resting HR throughout pregnancy
  • Physical findings:
    • ↑ 2nd heart sound split
    • Inspiration ⇒ distended neck veins
    • Low grade systolic ejection murmurs
  • Symptoms:
    • Some women have dizziness and syncope
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6
Q

Maternal Respiratory Changes

A

1° mediated by progesterone

Changes occur d/t ↑ oxygen demand of mother and fetus

  • Anatomic changes
    • Elevation of diaphragm ~ 4 cm
    • ↑ Chest diameter and circumference
  • Functional changes
    • ↑ Total body oxygen consumption
      • Gravid uterus, Respiratory muscles, Heart and kidneys, Mammary tissue, Elevated diaphragm
    • ↓ Residual volume
    • ↓ Functional residual volume
    • ↓ Total lung volume
    • ↑ Tidal volume
    • ↑ Inspiratory capacity and minute ventilation
      • ↑ ventilation and ↓ PCO2
        • Respiratory alkalosis
          • Compensated by ↑ excretion of bicarbonate via kidneys
          • Maintains normal maternal arterial pH
  • Physical findings: no change
  • Symptoms: Dyspnea
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7
Q

Maternal Hematologic Changes

A
  • ↑ Plasma volume (50%)
  • ↑ Red cell volume
  • ↑ Coagulation factors
  • ↑ total oxygen carrying capacity
    • D/t ↑ oxygen delivery to lungs and [Hb] in blood
  • Physiologic anemia
    • ↑ Plasma volume > ↑ RBC volume ⇒ normal anemia ass. w/ pregnancy
    • Worse around 30-34 wks
  • Lungs
    • ↑ Hb affinity for O2
  • Placenta
    • ↑ CO2 gradient b/t fetus and mother ⇒ allows for transfer of CO2 from fetus → mother
  • Symptoms: edema
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8
Q

Maternal Immune Changes

A

Physiologic ↑ in WBCs

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9
Q

Maternal Coagulation Changes

A

Hypercoagulable state

↑ Procoagulant factors

↑ Venous stasis

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10
Q

Maternal Renal Changes

A
  • Kidneys enlarge
  • Dilation of ureters
  • ↑ Renal plasma flow
    • ↓ BUN and creatinine
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11
Q

Maternal GI Changes

A
  • ↓ Tone and motility of stomach
  • ↑ GERD
  • ↑ Constipation
  • ↑ Risk of gallstones
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12
Q

Maternal Breast Changes

A

Initially enlarge d/t vascular engorgement

Further enlarge d/t ↑ mass

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13
Q

Maternal Skin Changes

A
  • Hirsutism
  • Striae
  • Hyperpigmentation
    • Linea nigra
    • Melasma
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14
Q

Maternal Physiological Changes

Summary

A
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15
Q

Placenta

Functions

A
  • Respiratory exchange
    • All gases cross placenta via simple diffusion
    • Dependent on blood carrying capacity of mother and fetus
    • Uterine and umbilical blood flow
  • Metabolite exchange
    • Glucose is the single primary metabolic substrate for placental metabolism
      • Facilitated diffusion
    • Other solutes dependent on concentration gradient, degree of ionization, size and lipid solubility
  • Hormone production
    • Estrogen
    • Progesterone
    • Human chorionic gonadotropin
    • Human placental lactogen
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16
Q

Fetal Circulation

A
  • Oxygenation of fetal blood occurs in the placenta
  • Oxygenated blood carried by umbilical vein → portal system
  • 50% of blood flows through ductus venosus → foramen ovale → left ventricle
  • Blood from proximal aorta → brain and upper body
  • Blood from distal aorta → lower body and umbilical arteries
  • Blood is deoxygenated and returns to the placenta
17
Q

Prenatal Care

Timeline

A
18
Q

Diagnosis of Pregnancy

A
  • History
    • Amenorrhea
    • Fatigue, N/V, breast tenderness
  • Physical
    • Enlarged, softened uterus
    • Chadwick’s sign: bluish discoloration of vagina and cervix
    • Hegar’s sign: softening of the cervix
  • Laboratory
    • UPT: measures HCG
      • HCG shares alpha subunit w/ LH, test must differentiate
        • Tests for beta subunit of HCG
      • ⊕ by 4 wks, best on early morning urine (highest concentration)
    • Serum pregnancy test: measures HCG
      • More sensitive and specific than urine
      • Can get a quantitative result
  • Ultrasound
    • Transvaginal: able to see at beta HCG of 1000-2000 mIU/mL
    • Transabdominal: able to see at beta HCG of 5000-6000 mIU/mL
    • Cardiac activity detectable at > 4000 MIU/mL (~12 wks)
19
Q

Dating

A
  • Gestational age
    • Number of wks since last period
    • Not conceptual age
  • Naegle’s rule
    • LMP + 7 days – 3 months = Estimated Delivery Date (EDD)
    • 1st day of LNM is crucial
  • Gestation is 40 +/- 2 wks
20
Q

Initial Labs

A
  • Blood type
    • Rh status is important
  • Antibody screen
  • CBC: H&H and Platelets
  • Maternal infections or immunity
    • Rubella; Hepatitis B surface antigen; Hepatitis C antibody; RPR; HIV; Gonorrhea; Chlamydia; Varicella
  • Pap for evaluation of cervical dysplasia/cancer
  • Cystic fibrosis and spinal muscular atrophy (SMA) carrier screening
  • Hemoglobin electrophoresis to look for Sickle Cell trait and other hemoglobinopathies
  • Urinalysis and Urine culture
21
Q

Prenatal Care

Summary

A
22
Q

Normal Labor

A
  • Progressive change in a woman’s cervix in the setting of regular, rhythmic uterine contractions.
  • Spontaneous contractions occur throughout pregnancy, most go unperceived
  • Contractions become stronger and more frequent toward term
  • Braxton-Hicks: contractions that are perceived but not associated w/ cervical change
    • False labor
    • Typically shorter and less intense than true labor
23
Q

Evaluation of Labor

Historical Aspects

A
  • Contractions every 5 minutes for 1 hour
  • Leaking of vaginal fluid
  • Significant vaginal bleeding
  • ↓ Fetal movement
24
Q

Evaluation of Labor

Physical Exam

A
  • Fetal heart tracing
  • Tocodynamometer: measurement of contractions
  • Cervical exam
    • Dilation
    • Effacement
    • Station
    • Fetal lie
    • Presentation
    • Position
25
Q

Cervical

Effacement and Dilation

A
  • Dilation: opening of cervical os
    • Measured in cm from 0-10
  • Effacement: shortening of cervical canal
    • Expressed as a percentage
26
Q

Station

A

Level of fetal presenting part in the birth canal in relation to ischial spines.

  • Measured as a 6- or 10-point scale
  • Zero station ⇒ fetal presenting part at the level of the ischial spines
  • Positive numbers ⇒ fetal presenting part below the level of the ischial spines
  • Negative numbers ⇒ fetal presenting part above the level of the ischial spines
27
Q

Fetal Lie & Presentation

A
  • Fetal Lie: relation of long axis of fetus w/ maternal long axis
    • Longitudinal
    • Transverse
    • Oblique
  • Presentation: what is the presenting part lowest in the birth canal
    • Vertex
    • Breech
28
Q

Position

A

Relation of presenting part to the right or left side of maternal pelvis.

29
Q

Physiology of Labor

A

6. HDS GI Repro (30 decks)

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