Fetal circulation + pregnancy Flashcards
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
amenorrhea 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 SFH 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)
Dating
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
Neonatal:hyperglycemia
Group B Strep - pregnancy
10-30%
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
Preeclampsia
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
Lactation
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 early: - 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
Late:
- 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
Hyperpigmentation:
- 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
