210/211/212: Normal and Abnormal Pregnancy, Anatomy and Pathology of Implantation Flashcards
How will the following change during pregnancy?
- D-Dimer:
- Alk phos:
- Albumin:
- D-Dimer: increase
- Does not indicate VTE - but pregnancy is a hypercoagulable state, so make sure not to miss?
- Alk phos: increase
- Albumin: decrease
In general, at what gestational age is it better to perform a preterm delivery than to manage expectantly?
(In situations like preeclampsia, PROM, etc)
34 weeks
Before 34 weeks, try to manage expectantly - usually delivery will occur within 1 week, but give a chance to administer antenatal steroids, give the baby a few extra days to grow
What defines fetal growth restriction?
Why is it important to diagnose?
Fetal growth below the 10th percentile
- Counsel pts on prognosis, options
- Start antenatal surveillance
- Administer antenatal steroids if preterm birth is looking likely
Remember some babies are completely healthy and just small! This is a somewhat arbitrary screening cutoff.
What defines preeclampsia?
New onset HTN + proteinuria
Defined as severe if ANY of the following are present, even w/o proteinuria
- BP > 160/110 on 2 occasions, at least 4 hours apart
- Maternal symptoms (headache, visual changes, RUQ pain)
- Hepatic injury
- Renal dysfunction
- Pulmonary edema
- Coagulopathy
- HELLP syndrome
- Eclampsia (seizures)
How will the following change during pregnancy?
- GFR:
- Serum CR:
- Ureter position:
- Kidney size:
- GFR: increase
- Serum CR: decrease (since RPF increases more than GFR)
- Ureter position: displacement, R>L
- Kidney size: increase slightly, with mild/moderate hydronephrosis
List 3 important steps in the management of preterm labor
- Give mom steroids -> accelerates fetal lung development
- Give mom penicillin: GBS prophylaxis
- Empirically, even if screening test has not been completed yet
- Give mom magnesium: fetal neuroprotection
- Reduces cerebral palsy risk
Describe the management of preeclampsia
Definitive treatment is delivery
If not severe and <34 weeks, may attempt expectant management
- Control BP
- MgSO4 to prevent seizure
- Give antenatal steroids (baby is probably going to be preterm, get the lungs developed)
How is isoimmunization managed?
The pregnancy at risk is the second pregnancy, after Rh(-) mother develops antibodies to Rh during first pregnancy
(If mother was not given Rh immmunoglobulin during first pregnancy)
- Look at serial antibody titers
- 1:32 and above (so 1:16 and 1:8), fetus is at risk of anemia
- Transfer adult RBCs to fetus to prolong gestation
What is the difference between spontaneous abortion and stillbirth?
Gestational age
- Spontaneous abortion
- Pregnancy loss < 20 weeks gestation
- Vast majority <8 weeks
- Stillbirth (aka intrauterine fetal demise)
- Pregnancy loss ≥ 20 weeks gestation
- MUCH less common than spontanteous abortion
List the causes of fetal vascular malperfusion (4)
- Umbilical cord abnormalities:
- Twisting
- Velamentous insertion (cord inserts in membrances at side instead of in the disc)
- Mechanical obstruction (knots or wrapped around the fetal body/neck)
- Thrombus formation
What physiologic difference will be present in the chest x-ray of a pregnant person?
Enlarged cardiac silhouette due to elevation of the diaphragm
Heart will look too big, but it’s fine
How do estrogen and progesterone affect the uterus during pregnancy?
Estrogen -> Uterine hypertrophy (cells get bigger)
Progesterone -> Relaxation of uterine walls so fetus can grow
Which umbilical vessels deliver oxygenated blood to the fetus?
Umbilical vein (1)
Umbilical arteries (2) deliver deoxygenated blood from fetus to placenta
How will the following change during pregnancy?
- HR:
- CO:
- BV:
- SV:
- BP:
- HR: increase
- CO: increase
- BV: increase
- SV: increase
- SVR: decrease
- BP:
- 1st trimester: normal
- 2nd trimester: may dip a bit
- “normal BP” may actually be hypertension
- 3rd trimester: back to normal
At what gestational age does the fetus begin to synthesize its own thyroid hormone?
10 weeks
Relies on maternal TH until then
How will the following change during pregnancy?
- Clotting factors:
- tPA:
- Protein S:
- Activated protein C:
- Clotting factors: increase
- tPA: increase
- Protein S: decrease
- Activated protein C: decrease
Also, RBCs and plasma volume both increase, but plasma volume increases more -> physiologic anemia, blood is more dilute, protective against hemorrhage
Onset of labor before what gestational age counts as preterm?
<37 weeks
37 weeks + 0 days = term
Does the umbillicl cord contain maternal blood or fetal blood?
List the vessels in the cord
Fetal blood only
- 1 umbilical vein carries oxygenated blood from placenta to fetus
- 2 umbillical arteries carry deoxygenated blood from fetus to placenta
What is the most common cause of spontaneous abortion?
Chromosomal abnormalities
Describe the management of placenta previa
- Pelvic rest
- Manage expectantly if <37 weeks
- Planned C-section at 37 seeks
- Labor is a risk factor for maternal hemorrhage
What is happening during stage 1 of labor?
Onset of labor -> full cervical dilation
- Latent phase happens slowly
- Active phase = acceleration
- Usually at 4-6 cm
- Usually happens more quickly in people who have delivered a baby before
List the stages of labor and what is happening at each stage
- Stage 1
- Onset of labor -> full cervical dilation
- Stage 2 (pushing)
- Full cervical dilation -> delivery of fetus
- Stage 3
- Delivery of neonate -> delivery of placenta
Describe the pathophsyiology of isoimmunization
Rh (-) mother is exposed to Rh (+) fetal blood during pregnancy/delivery
- -> Maternal production of antibodies
- -> Next pregnancy = antibodies attack fetal RBCs, can cause fetal anemia, high volume congestive heart failure
- Prevent by administering Rh immune globulin to all pregnant women who are Rh (-) at 28 weeks, after delivery, and any time there is concern for breakage of the feto-maternal barrier*
- Manage by transfering adult RBCs to fetus to prolong gestation if fetal anemia is developing*
Which two classes of drugs can be given to stop labor?
- Beta-2 agonists (terbutaline)
- Maintain relaxation of the myometrium
- Calcium channel blockers (nifedipine)
- Prevent depolarization of myometrial cells
Neither work very well. Buy a little time to administer steroids and develop fetal lungs.
The corpus luteum supports pregnancy until __ weeks gestation
The corpus luteum supports pregnancy until 7 weeks gestation
Then placenta starts producing own progestrone
How will the following change during pregnancy?
- Minute ventilation:
- Residual volume:
- Tidal volume:
- Functional residual capacity:
- Acid/base balance:
- Minute ventilation: Increase
- Tidal volume: Increase
- Residual volume: Decrease
- Functional residual capacity: Decrease
- Acid/base balance: Respiratory alkylosis
- Due to decrease in maternal pCO2, compensated by excretion of bicarbonate
Most changes are compensatory 2/2 elevated diaphragm
What is an “abnormally adherent placenta”?
What are the 3 different types?
The placenta implants into a layer of the uterus that is deeper than the decidua
- Accreta = implantation on the myometrium
- Increta = invasion into the myometrium
- Percreta = invasion through uterine serosa into adjacent structures
What protective structure is lost if a fetus has velamentous umbilical vessels?
Wharton’s jelly
- Supposed to surround the umbilical vessels
- If cords insert directly into the membrane (instead of the disk), they are at risk for rupture
Which situation is more urgent:
- Bleeding from placenta previa
- Bleeding from vasa previa
How do you tell them apart on presentation?
b. Bleeding from vasa previa
More dangerous because fetal blood - fetus can bleed out very quickly - do an emergency c-section!! (within seconds-minutes)
Vasa previa will have worrisome fetal monitoring; placenta previa will have reassuring fetal monitoring
Also, Apt test: fetal hemoglobin is resistant to lysis by alkaline solutions (but realistically, you don’t have time to do this test)
How is cervical insufficiency managed?
Cerclage
- If CI is happening => emergent cerclage
- Contraindications: contractions (implies labor), fetal demise, infection
- If risk factors but has not happened yet => prophylactic cerclage
Cerclage = suture that gives structural integrity/closure of cervix
What microscopic findings may be present in vaginal secretions in PROM (premature rupture of membranes)?
“ferning” pattern
Proves that the fluid is amniotic, not another vaginal secretion
- Caused by salt in the amniotic fluid
Which tumor of gestational trophoblastic tissue is large and hemorrhagic?
Choriocarcinoma
Highly malignant, rapidly invasive and widely metastasizing
Much less common than moles
Less hemorrhage in partial and complete moles
What are the serious consequences of fetal vascular malperfusion?
- Cerebral palsy
- Intrauterine or neonatal fetal demise
List the 3 membrandes of the placenta, from fetus to uterus
- Amnion (fetal)
- Chorion (fetal)
- Parietal decidua (maternal layer)
- Endometrium that is modified to support pregnancy
They are in alphabetical order
List 3 tumor types that can arise from gestational trophoblastic tissue
- Complete hydatidiform mole (no maternal DNA; 46XX or 46XY)
- Partial hydatidiform mole (maternal DNA; 69XXX of 69XXY)
- Choriocarcinoma
- Pure trophoblastic proliferation; no chorionic vili
- Large, malignant
- More rare
List 2 problems that can occur with twin vasculature
-
Twin-to-twin transfusion syndrome
- Donor twin is anemic
- Recipient twin is plethoric
- Artery of donor to vein of recepient
-
Twin reversed arterial perfusion
- Pump twin -> hydrops
- Can have relatively normal gestation if acardic twin is removed
- Other twin is acardiac (no heart at all)
- Pump twin -> hydrops
May occur in monochorionic twin placentas
How will blood sugar change during pregnancy?
Mild fasting hypoglycemia (increased insulin)
Mild post-prandial hyperglycemia (insulin resistance)
If a twin pregnancy is diamniotic, what can you say about whether the twins are monozygous or dizygous?
May be either
- Dizygous twins are ALWAYS diamniotic
- Monozygous twins are usually diamniotic, but can be monoamniotic
Describe the pathogenesis of preeclampsia
Failure of spiral artery to transform into a high-capacitance vessel
- -> Cannot perfuse chorionic villi
- -> Hypoperfusion
- -> Placental ischemia
- -> Immune reaction involving cytokines
- -> Hypertension
How does the cervix change during pregnancy?
Chadwick sign present (blueish tinge to tissue)
Due to hypertrophy and hyperplasia of cervical glands, eversion of proliferating columnar endocervical glands
What is cervical insufficiency, in the context of preterm labor?
Painless cervical dilation with the absence of uterine contractions
- Usually 16-24 weeks
- May be related to collagen abnormalities (ex: Ehler’s Danlos)
- Can lead to prolapse of amniotic sac→ miscarriage
If uterine contractions + cervical dilation = preterm labor; CI is NOT preterm labor
What triggers labor?
(How do the mother and fetus know when it’s time?)
The placental clock determines the timing of labor
- Cortisol releasing hormone (CRH) produced by the placenta
- Stimulates maternal adrenals to produce DHEAS
- Signals placenta to make estrogen
- Contractions
- Signals fetal pituitary, adrenals and lungs
- Fetal adrenal and pituitary activity
- Lung maturation, surfactant production
Where in the fetus/placenta will we see inflammation in an ascending (vaginal) vs. hematogenous infection?
- Ascending:
- Maternal neutrophils in maternal arteries, move to amniotic fluid
- -> Fetal neutrophils in the umbillical cord and on the chorionic plate
- Hematogenous
- Fetal inflammation in villi and intervillous space
- Either chronic (lymphocytes) or acute (neutrophils) villitis
If a twin pregnancy is monochorionic, are the twins monozygotic or dizygotic?
Monozygotic (identical)
Very rare (4%) and very risky
Where does amniotic fluid come from…
- <16 weeks:
- >16 weeks:
- <16 weeks: diffusion from maternal circulation
- >16 weeks: fetal urine
During gestation, where is the fetoplacental interface?
What are the boundaries of the fetal and maternal portions, respectively?
Chorionic villous = fetoplacental intervace
-
Fetal side: Chorionic villi
- Cytotrophoblasts + syncytiotrophoblast
- As the barrier thins later in pregnancy, syncytiotrophoblasts only
-
Maternal side:
- Extravillous trophoblasts
- Remodeled vessels
- Basal plate
Basically, the villi/villous trees are fetal - the trophoblasts are maternal. They touch to exchange gas, nutrients, but blood does not mix!
What is the etiology of fibrinoid necrosis in placental vessels?
Maternal vascular malperfusion
- Caused by maternal HTN or preeclampsia
- Results from failure of trophoblasts to remodel maternal spiral vessels into high-capacitance (high-flow vessels)
- -> chronic hypoxia
- -> fibrinoid necrosis
What is considered “normal pregnancy weight gain”?
25-35 lbs, if normal pre-pregnancy weight
Obese/overweight pregnant people do not need to gain as much
- Equates to ~300 extra calories/day*
- But tbh if I’m every growing a baby inside of me I will eat as much as I please*
List the 3 shunts in fetal circualtion and what they bypass
-
Ductus venosus
- Portal vein -> IVC
- Bypasses liver
-
Foramen ovale
- Right atrium -> left atrium
- One way valve, high to low pressure
- Bypasses RV, lungs
-
Ductus arteriosus
- Pulmonary artery -> aorta
- Bypasses fetal lungs, LA, LV
Describe the difference in presentation:
Placental abruption vs. placenta previa
-
Placental abruption
- Vaginal bleeding + uterine contractions/pain
- Pain does not stop when contraction ends
- Caused by placenta separating from wall of uterus
-
Placenta previa
- Painless vaginal bleeding
- Caused by placenta covering cervical os
- Placental abruption is a little bit more urgent - manage expectantly if mom and fetus are doing well, deliver if either is looking distressed*
- Placenta previa = initiate pelvic rest, plan a c-section at 37 weeks*
How can isoimmunization be prevented?
Administer Rh immune globulin to all pregnant women who are Rh (-) at 28 weeks, after delivery, and any time there is concern for breakage of the feto-maternal barrier
- This prevents mom from developing atigens against Rh:*
- The anti-Rh IgG neutralizes Rh-expressing fetal RBCs in maternal circulation before the maternal immune system can detect and become sensitized to fetal RBCs*
- Thank you @Ben Gastevich!*
Oxygenated blood is delivered to the fetus from the ____________
Umbilical vein (1)
There are 2 umbilical arteries with deoxygenated blood.
A 33 year old G3P2 at 28 weeks presents for a flu shot. She appears well but her HR is 100bmp and her BP is 90/60. Chest x ray demonstrates a mildy enlarged cardiac silhouette. Elevated D-dimer and mild respiraroy alkalosis. What is the diagnosis?
NORMAL PREGNANCY
HR increases in pregnancy
BP decreases in 2nd trimester
Enlarged cardiac silhouette due to high diaphragm.
Normal elevation in D-dimer.
Normal respiratory aklalosis.
A 38 year old G2P1 at 7 weeks is taken to the operating room for ovarian torsion. Left ovary is removed. There was a corpus luteum cyst on the ovary. What should be given to maintain pregnancy?
Progesterone!
Corpuse luteum makes progesterone for first 7 weeks before the placenta takes over.
