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Flashcards in Fetal circulation + pregnancy Deck (52):

Ductus Venous

highly oxygenated blood comes from placenta to fetus via umbilical vein --> directed to IVC via this shunt (bypass liver)
Travels directly to heart to move to brain


Foramen ovale

cardiac ventricles work on parallel
Allow highly oxygenated blood to move from right atrium to left atrium --> supply brain/heart


Ductus arteriosus

lungs not needed for oxygenation
90% blood from RV bypassed via this shunt from pulmonary artery to descending aorta
RV pumps deoxygenated blood to lower body and back to placenta


Umbilical vein

from umbilicus to DV
becomes ligamentum teres hepatis


Ductus venosus

from umbilical vein to inferior vena cava
becomes ligamentum venosum


Foramen ovale

from RA to LA
becomes closed atrial wall


Ductus arteriosus

from pulmonary artery to descending aorta
becomes ligamentum arteriosum


Umbilical artery

from common iliac artery to umbilicus
becomes superior vesical arteries; lateral vesicoumbilical ligaments


Positive dx of pregnancy

fetal heart
fetal movement
visualization of fetus


probable Dx of pregnancy

enlarged uterus
uterine/cervical changes
palpation of fetus
Braxton hicks contractions
pregnancy test


Presumptive Dx of pregnancy

breast changes
congestion of vagina
skin changes
common symptoms (nausea, fatigue, bladder irritability)


Naegle rule

LMP + 7 days - 3months + 1 year


Ultrasound dating

measurement of fetal size compared to normal curves
earlier scan more accurate ( LMP if within 1 week difference
if over >2 weeks difference: take note if fetal growth restricted


First prenatal visit

confirm pregnancy
do not have to repeat pregnancy test if patient has already done one
medical history
risk assessment
full physical + pap and swabs


Prenatal care

pregnancy recommendations
smoking cessation
alcohol/illicit drugs
physical activity
sexuality - semen may have prostaglandins; if prematurity risk high, advise against sexual intercourse
supplements (folate, iron)
work environment


Routine investigations during pregnancy

weight, BP
urine dip for protein
Fetal HR
fetal growth - SFH +/- ultrasound


1st visit labs for pregnancy

Blood type/screen (repeat at 26-28 wks esp important in Rh- women)
CBC - Hb electrophoresis if indicated
Rubella (can't vaccinate since live attenuated)
syphilis - can treat
HBsAg - can vaccinate if needed
HIV - counsel
+/- HC
Swabs GC/CT
Pap if needed
+/- TSH (common)
Ultrasound - dating


Ultrasound schedule during pregnancy (N)



Genetic screening

all pregnant women should be offered
blood test available in first/second trimester, combination produces a risk estimate
CVS 10-13 weeks
amnio >15 weeks


Gestational diabetes screen

24-26 weeks
75g OGT - do earlier if at risk (twins - hPL, ethnicity, previous DM)


GBS screening

35-37 weeks
for risk of sepsis and meningitis


Anemia in pregnancy

Hb 100 = anemia
Physiologic anemia of pregnancy
check for Fe deficiency with ferritin


Physiologic anemia of pregnancy

due to 50% increase in plasma volume compared to only 20-30% increase in erythrocyte mass
generally normocytic, >105


Risks of GDM

maternal: operative delivery, 50% risk T2DM
Fetal: macrosomia (sugar crosses but insulin doesn't; fetus produces insulin and insulin-like growth factor), stillbirth


Group B Strep - pregnancy

universal screening at 35-37 weeks
don't screen too early - part of normal flora


GBS who to treat

treat GBS+ when membranes rupture
GBS bacteriuria in this pregnancy - treat, don't need to swab
Prior GBS affected child: treat, don't need to screen
GBS unknown and ROM > 18 hours: treat
GBS+, intrapartum: treat

Don't need to treat:
- elective C-section (if membranes don't rupture beforehand)
- GBS+ 1st pregnancy and infected baby --> treat child, don't need to screen


GBS treatment

can't eradicate!
IV penicillin
if allergic: anaphylaxis: clindamycin/erythromycin
at least 2 intrapartum doses to mom


Small SFH, lack of interval growth

ask about fetal movement
broad differential
maternal: HTN, chronic medical conditions, malnutrition, weight loss, medications, substance use, rupture membranes
Fetal: chromosomal, growth restriction, infection
Placental: poor implantation, chronic abruptio, oligohydramnios

US if SFH >3cm behind GA

Non-stress test: 20-45 min fetal heart rate tracing


Fetal Heart visualization

normal maternal BMI:
5-6 wk on transvaginal ultrasound
8 wk on transabdominal ultrasound


Fetal HR audio

10-12 wk with Doptone


Hypertension in pregnancy

single elevated BP: 30-70% of women with single elevated BP will be normal on repeat testing


Dx of gestational HTN

SOGC: diastolic > 90 based on average of >=2 measurements taken in same arm >15 min apart
diastolic is a better predictor of adverse pregnancy outcomes
Systolic > 160 diagnostic
BUT keep an eye on systolic > 140



gestational HTN + proteinuria (>=2 2+ on dipstick, 0.3 g/day or 30 mg/mol on spot PCR)


GERD in pregnancy

more common due to:
- progesterone affecting smooth muscle
- delayed gastric emptying
- mass effect from uterus

Drugs in pregnancy:
- some drugs cross placenta
- ranitidine is okay


Postpartum blues

80% women, lasting


Postpartum depression

10-25% women = medical condition needing treatment


Contraception post-partum

Combined OCP can affect milk supply - progesterone less effect but also less effective as contraception
IUD: wait 6 weeks postpartum to allow uterine involution


Lactation as contraception

Exclusive breastfeeding at 6 mo: 95% effective
non-exclusive: 50% ovulate by 6 weeks
non-BF: often resume by 45 d


Breast changes during pregnancy

early: tenderness/paraesthesias
>2 mo: increase in size, delicate veins visible
- nipples enlarge, more deeply pigmented/erectile
Later: colostrum can be expressed from nipples by gentle massage
- areolae become broader, more deeply pigmented
some striations if breasts become large


Cervical changes during pregnancy

softening/cyanosis as early as 1 mo after conception
- increased vascularity, edema, hypertrophy/hyperplasia of cervical glands

Proliferation of glands:
- produce mucus rich in Ig and cytokines, may act as immunological barrier
mucus plug expelled at onset of labour/earlier --> bloody show

Small amounts of smooth muscle, mostly CT
collagen-rich CT rearranged = ripening
- decreases collagen/Proteoglycan concentrations, increase water content
- regulated by local E and P


Uterine changes during pregnancy

500-1000x bigger
- most marked in fundus
increase in weight to 1.1 kg
cavity ~5L or >20 L
- hypertrophy/stretching of muscle cells stimulated by E, maybe P
- production of new myocytes limited
- accumulation of fibrous tissue, esp in external muscle layer
- increase in elastic tissue content

- relatively thin-walled muscular organ


Pulmonary changes during pregnancy

diaphragm rises ~4 cm
thoracic circumference increases ~6 cm
diaphragmatic excursion increases
FRC decreases 20-30%
inspiratory capacity increases 5-10%
total lung capcity unchanged/decreases by


Oxygen delivery during pregnancy (maternal blood)

amount of O2 delivered to lungs by increased tidal volume exceeds O2 requirements
total Hb mass increases
maternal A-V O2 difference increased
O2 consumption increases~20%


Acid-base equilibrium (maternal) during pregnancy

increased awareness of a desire to breathe
- physiological dyspnea caused by increased tidal volume that lowers blood PCO2 slightly

Respiratory alkalosis
- to compensate: HCO3- decreases
- blood pH increases only minimally
- shift O2 dissociation curve to left: Bohr effect --> decrease O2 releasing capacity of maternal blood


Cardiovascular changes during pregnancy

Plasma volume increases by 45%
- P and E on kidney --> Renin --> RAS --> Na retention (protection from hemorrhage)
Increase renal EPO production: RBC mass increase 20%
- hemoglobin falls
White cell count rises, peaks after delivery
Fall in peripheral vascular resistance by 20%
- E & P --> vasodilation
- systolic/diastolic BP fall --> reflex increase in HR by 25%
- SV increased by 25%, CO increased by 50%


Coagulation during pregnancy

plasma concentrations of fibrinogen/all clotting factors gradually increase
increase in platelet production (but relative thrombocytopenia because of increased activity and consumption)
increase in fibrinolysis


Metabolic changes during pregnancy

insulin production rises
increased insulin resistance caused by placental hormones (hPL)
Any carbohydrate load will cause greater than normal increase in plasma glucose concentrations --> facilitates glucose transfer


GU changes during pregnancy

renal plasma flow, GFR increase
urea/creatinine/urea clearance and excretion of HCO3- increased --> plasma concentration decrease
Activities of RAS, aldosterone, progesternoe increase --> water retention, decreased plasma osmolality
resorption of glucose falls
progesterone-mediated ureteric smooth muscle relaxation --> urinary stasis --> increased risk for UTI, urinary incontinence


GI changes during pregnancy

Heartburn common
- increased intraabdominal pressure
- progesterone-mediated reduction in LES tone
Pregnancy gingivitis
- gums hyperemic, softened
Hemorrhoids common
More likely to develop gallstones


Immune tolerance during pregnancy

Semiallogeneic fetus allowed to growt within maternal uterus


MSK changes during pregnancy

progressive lordosis
sacroiliac/sacrococcygeal/pubic joints increased mobility


Skin/orofacial changes during pregnancy

abdominal wall: striae gravidarum
- up to 90% of women
- usually more accentuated in those with darker complexion
- melanocyte-stimulating hormone level elevated
- E and P - melanocyte-stimulating effects???

Vascular changes:
- angiomas: esp on face, neck, upper chest, arms; palmar erythema (due to hyperestrogenemia??)
increased cutaneous blood flow; dissipate heat generated by increased metabolism