Pregnancy Physiology Lecture Powerpoint Flashcards
Recall the 3 trimesters of pregnancy
0-13 is first
14-28 is second
28-end (typically 40) is third
Most common signs that cause patients to come for a pregnancy eval
missed menstrual period (a week to 2 weeks late)
Gestational age =
Embryonic age (from fertilization) + 2 extra weeks (from the last period)
ASSUME GESTATIONAL AGE UNLESS OTHERWISE INDICATED***
Symptoms 1-2 weeks after fertilization in the mother (5)
- breast tenderness
- nipple sensitivity
- extreme fatigue**
- nausea
- urinary frequency
Pelvic exam uterus sizing
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
Molar pregnancy
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)
hCG levels during pregnancy
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
hCG function in pregnancy (5)
- 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)
Early pregnancy factor (EFP) test
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
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
….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
Fetal movement should occur at least at ___ weeks gestation otherwise trouble!
19
At what week can the fetal heart be demonstrated to beat on TRANSVAGINAL ultrasound, how about on low doppler ultrasound?
4-6 weeks post conception or 6-8 gestational
10-12 weeks gestational age
Blighted ovum
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
Hegar sign***
Palpable softening of the lowest part of the uterus at 6 weeks (just above the cervix)***, indicative of probable evidence of pregnancy
McDonald sign***
When the uterine body and cervix can be easily flexed against once another*** indicative of probable evidence of pregnancy
Chadwick sign***
Mucus membranes of vulva, vagina, and cervix becoming congested and having blue hue between 6-8th weeks gestation*** indicative of probable evidence of pregnancy
Goodell sign**
Softening of the cervix by beginning of 2nd month of pregnancy** indicative of probable evidence of pregnancy
Braxton hicks contractions
Not normally felt until 3rd trimester but some women in the 1st trimester, painless and irregular contractions “false labor pains”
Nausea in pregnancy and how is it relieved?
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
Linea nigra
Dark lines descending from the umbilicus due to deposits of melanin that falls off upon delivery
Bladder irritability in pregnancy (4)
- 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
Pseudocyesis
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
Fetoplacental unit incomplete upon observation of delivery indicates…
….partial retention of part of the placenta, requires immediate removal to prevent bleeding complications
3 layers of adrenal cortex and what they secrete,what does the adrenal medulla secrete?
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
Human placental lactogen (hPL) and what 2 conditions do low values raise concern for?
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
Progesterone definition
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
Most abundant form of estrogen of pregnancy, young lady, and old lady
What does a sudden decline of estriol in maternal circulation indicate?
Estriol, estradiol, estrone
-fetal compromise
glucocorticoids function in pregnancy
Maturation of the lungs (differentiation of type ii alveolar cells secreting surfactant)
Relaxin function
Has a role in cervical ripening and pubic bone relaxation, as well as hemodynamic changes, helps the cartilage throughout the entire body relax
Oxytocin function
Causes uterine contractions, role in initiating labor is unclear, administered can induce labor but only at or near term
Alpha fetoprotein (AFP) function**
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)
Anatomic changes in pregnancy (8)
- 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
Uterine enlargement movement thruout pregnancy (12, 16, and 36 weeks)
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
Physiologic changes of pregnancy (7)
- 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
BUN and creatinine in pregnancy**
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,
Placenta lacks enzyme 17alpha hydroxylase and therefore cannot convert progesterone to…
….estrogen, must use androgens from fetal adrenal reticularis
ACTH is produced in the placenta and resistant to the…
….dexamethasone suppression test
Alk phos, choleseterol, serum iron, and total iron binding capacity, cortisol levels in pregnancy
Doubled not accurate decrease increased nearly 3x higher than nonpregnant reaching levels of cushings
