Pregnancy Physiology Lecture Powerpoint

Question 1

Recall the 3 trimesters of pregnancy

Answer 1

0-13 is first
14-28 is second
28-end (typically 40) is third

Question 2

Most common signs that cause patients to come for a pregnancy eval

Answer 2

missed menstrual period (a week to 2 weeks late)

Question 3

Gestational age =

Answer 3

Embryonic age (from fertilization) + 2 extra weeks (from the last period)

ASSUME GESTATIONAL AGE UNLESS OTHERWISE INDICATED***

Question 4

Symptoms 1-2 weeks after fertilization in the mother (5)

Answer 4

• breast tenderness
• nipple sensitivity
• extreme fatigue**
• nausea
• urinary frequency

Question 5

Pelvic exam uterus sizing

Answer 5

Should be able to correlate uteral enlargement with menstrual dates, if smaller than expected may be ectopic, spontaneous abortion, etc. and if uterus larger than expected may indicate uterine leiomyomata, twin gestation, molar pregnancy

Question 6

Molar pregnancy

Answer 6

When a nonviable fertilized egg implants in the uterus and will fail to come to term, seen most often in patients under 20 or over 45, causes mass to grow in the uterus that appears as a “snowball” shape on ultrasound and can become cancerous excreting excess, extremely high hCG (extreme nausea and other symptoms)

Question 7

hCG levels during pregnancy

Answer 7

Detected in serum levels as early as 7-9 days after ovulation, very soon after implantation it begins secreting, being 50-250 mIU/ml by time of first missed period, First 3 to 4 weeks after fertilization should double every 2 days, peaks 60-70 days (100k mIU/mL!) after fertilization then decreases dropping within 4 weeks completely off upon completion/late term abortion, if abnormally low can be due to spontaneous abortion or ectopic pregnancy, if abnormally high can be due to multiple pregnancies or molar pregnancy

Question 8

hCG function in pregnancy (5)

Answer 8

• Maintain corpus luteum
• stimulate both adrenal and placental steroidogenesis
• stimulate fetal testes to secrete increasing amounts of testosterone to induce internal virilization
• hCG is immunosuppressive and may be involved in materal lymphocyte function
• hCG possesses thyrotrophic activity (see hypothyroidism in mother after birth before returning to rise)

Question 9

Early pregnancy factor (EFP) test

Answer 9

A product of platelet activation and cell proliferation secreted into circulation from cytoplasm, earliest known marker of fertilization and can be measured to determine if pregnant almost immediately

Question 10

Even 2 weeks after first semester abortion hCG levels may be…
If it remains at that value even after the allotted time, might be indicative of these 3 pathologies

Answer 10

….very high, with pregnancy tests still reading positive up to 40 days after 1st trimester abortion

• continuing missed intrauterine pregnancy
• retained placental fragment
• ectopic pregnancy

Question 11

Fetal movement should occur at least at ___ weeks gestation otherwise trouble!

Answer 11

19

Question 12

At what week can the fetal heart be demonstrated to beat on TRANSVAGINAL ultrasound, how about on low doppler ultrasound?

Answer 12

4-6 weeks post conception or 6-8 gestational

10-12 weeks gestational age

Question 13

Blighted ovum

Answer 13

Loss of definition of gestational sac or absence of fetus by 7-8 weeks of amenorrhea despite the body still believing it is pregnant for several more weeks before it eventually miscarries resulting in heavier menses as the tissue collapses, can be confirmed by ultrasound to see the empty sac

Question 14

Hegar sign***

Answer 14

Palpable softening of the lowest part of the uterus at 6 weeks (just above the cervix)***, indicative of probable evidence of pregnancy

Question 15

McDonald sign***

Answer 15

When the uterine body and cervix can be easily flexed against once another*** indicative of probable evidence of pregnancy

Question 16

Chadwick sign***

Answer 16

Mucus membranes of vulva, vagina, and cervix becoming congested and having blue hue between 6-8th weeks gestation*** indicative of probable evidence of pregnancy

Question 17

Goodell sign**

Answer 17

Softening of the cervix by beginning of 2nd month of pregnancy** indicative of probable evidence of pregnancy

Question 18

Braxton hicks contractions

Answer 18

Not normally felt until 3rd trimester but some women in the 1st trimester, painless and irregular contractions “false labor pains”

Question 19

Nausea in pregnancy and how is it relieved?

Answer 19

Occurs in 2-12 weeks of pregnancy in approx half of pregnant patients, subsides 6-8 weeks later, rarely persists thru whole pregnancy (hyperemesis gravidarium), rarely occurs after 1st trimester, most severe upon waking and tends to lessen as day progresses, treated with simple things such as food avoidance etc and occasionally a zofran

Question 20

Linea nigra

Answer 20

Dark lines descending from the umbilicus due to deposits of melanin that falls off upon delivery

Question 21

Bladder irritability in pregnancy (4)

Answer 21

• early in pregnancy enlarging uterus puts pressure on bladder
• hormonal changes increase urinary frequency
• usually resolves by 2nd trimester
• returns late pregnancy when head descends into pelvis and puts pressure on bladder

Question 22

Pseudocyesis

Answer 22

Imaginary pregnancy with high progesterone and hCG, most often occurs in women nearing menopause or young who have an unfulfilled desire for pregnancy, will swear they are feeling the baby moving despite no actual fetus has implanted in them

Question 23

Fetoplacental unit incomplete upon observation of delivery indicates…

Answer 23

….partial retention of part of the placenta, requires immediate removal to prevent bleeding complications

Question 24

3 layers of adrenal cortex and what they secrete,what does the adrenal medulla secrete?

Answer 24

Zona glomerulosa (aldosterone)
Zona fasiculata (cortisol)
Zona reticularis (androgens, DHEA - largest portion during developing fetus and stimulated by increased prolactin in fetal pituitary)

Catecholamines (epi and norepi

Question 25

Human placental lactogen (hPL) and what 2 conditions do low values raise concern for?

Answer 25

Originates in the placenta and is present around the 5th week of pregnancy, antagonizes cellular action of insulin decreasing glucose utilization in mother shifting glucose availability toward the fetus, measured in 2nd trimester if concern
-threatened abortion and IUGR

Question 26

Progesterone definition

Answer 26

Most important hormone in pregnancy, in luteal phase induces secretory changes in the endometrium, typically well above 20mg/ml but if <5ng/mL indicates a nonviable pregnancy, acts by preventing uterine contractions, produced by ovary up to 6-7 week of pregnancy and then transfer to the placenta, fetus inactivates by transformation of it into corticosteroids at the adrenal gland

Question 27

Most abundant form of estrogen of pregnancy, young lady, and old lady

What does a sudden decline of estriol in maternal circulation indicate?

Answer 27

Estriol, estradiol, estrone

-fetal compromise

Question 28

glucocorticoids function in pregnancy

Answer 28

Maturation of the lungs (differentiation of type ii alveolar cells secreting surfactant)

Question 29

Relaxin function

Answer 29

Has a role in cervical ripening and pubic bone relaxation, as well as hemodynamic changes, helps the cartilage throughout the entire body relax

Question 30

Oxytocin function

Answer 30

Causes uterine contractions, role in initiating labor is unclear, administered can induce labor but only at or near term

Question 31

Alpha fetoprotein (AFP) function**

Answer 31

produced by the fetal liver, measured in the 2nd trimester, tends to be elevated in pregnancies supporting fetuses with neural tube defects and lowered in cases of down syndrome (do an amniocentesis if doesn’t match percentile for week gestational age)

Question 32

Anatomic changes in pregnancy (8)

Answer 32

• increased vasularity
• increased pigmentation of face, areola, abdomen (linea nigra), and genitalia
• head sees mild changes in the scalp, excessive oil or dryness
• friable gums
• increased respiratory effort and rate
• exaggerated heart sounds
• abdomen distension, diminished bowel sounds and displacement
• musculoskeletal relaxation of pelvis, lordosis, sciatica

Question 33

Uterine enlargement movement thruout pregnancy (12, 16, and 36 weeks)

Answer 33

Enlargement should occur in linear faction 1cm per week

• at 12 weeks fundus at the pubic symphysis
• 16 weeks midway to the umbilicus
• 36 weeks just below the xiphoid process

Question 34

Physiologic changes of pregnancy (7)

Answer 34

• 50% increase in plasma volume (physiologic anemia)
• increased o2 carrying capacity of RBC’s
• 20-30% increase in stroke volume
• 40% increase in cardiac output
• systolic pressure falls only slightly, diastolic decreases markedly (might pass out)
• mechanical circulatory obstruction of inferior vena cava when lying supine
• slight fall in inspiratory reserve because of diaphragm compression but total body o2 consumption increases

Question 35

BUN and creatinine in pregnancy**

Answer 35

Renal blood flow and GFR increase early in pregnancy and plateau at 40% above nonpregnant levels, BUN and creatinine should be decreased due to increased GFR, in pregnancy induced hypertension, values increase to nonpregnant levels due to pathological arterial spasm and vasoconstriction,

Question 36

Placenta lacks enzyme 17alpha hydroxylase and therefore cannot convert progesterone to…

Answer 36

….estrogen, must use androgens from fetal adrenal reticularis

Question 37

ACTH is produced in the placenta and resistant to the…

Answer 37

….dexamethasone suppression test

Question 38

Alk phos, choleseterol, serum iron, and total iron binding capacity, cortisol levels in pregnancy

Answer 38

Doubled
not accurate
decrease
increased
nearly 3x higher than nonpregnant reaching levels of cushings