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a_GYNGU > 11/17- Placental Pathophysiology > Flashcards

11/17- Placental Pathophysiology Flashcards

1
Q

When does fertilization occur? Where?

A

3-4 days after ovulation

  • Occur within Fallopian tube
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2
Q

Describe implantation

  • Timeline (start/end)
  • Stage that adheres/invades
A
  • Begins 6-8 days post ovulation
  • Completed 11-12 days post ovulation
  • Blastocyst becomes adherent to and invades into the secretory endometrium
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3
Q

What is the blastocyst?

  • Cell layers and differentiation
A
  • Forms from the multicell morula at 4 days post ovulation
  • Outer cell layer becomes the placental disc, chorion and villi
  • Inner cell layer becomes amnion, umbilical cord and embryo
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4
Q

When does hCG become measurable?

A

8-10 days after fertilization (in serum)

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5
Q

What is the function of the placenta?

A
  • Transport O2 and nutrients to and remove CO2 and waste from the fetus
  • Physical barrier to transport to certain substances, drugs and infectious agents
  • Immunologic barrier that prevents cell trafficking between mother and baby
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6
Q

Describe maternal and fetal blood flow and villous permeability of the placenta

A

Maternal blood flow

  • Implantation, spiral arteries, blood pressure, hemoglobin

Fetal blood flow

  • Placental size, fetal blood vessels: umbilical cord to villous capillaries

Villous permeability

  • Maturation, basement membrane, stromal cellularity, edema, intervillous space
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7
Q

What is decidua? Function?

A

Decidua is endometrium that has been hormonally influenced by pregnancy

  • Acts as a physical and immunologic barrier between placental (fetus) and uterine (maternal) tissues
  • Nitabuch’s fibrinoid between decidua and villi
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8
Q

What is seen here?

A

Nitabuch’s fibrinoid: between decidua and villi

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9
Q

Describe ectopic pregnancy

  • Prevalence
  • Most common location
  • Presentation and timeline
A
  • 1/150 pregnancies
  • 90% in the fallopian tubes
  • Presentation typ ~6 weeks after last missed menstrual period
  • Rupture of tube and intraabdominal hemorrhage may be life-threatening
  • Rarely extruded from fallopian tube intact to become an intraabdominal pregnancy
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10
Q

What is seen here?

A

Tubal pregnancy

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11
Q

What are consequences of intraabdominal pregnancy?

A
  • Fetal compression
  • Lithopedion
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12
Q

What is placenta previa?

A

Abnormally low implantation completely covering cervix

  • Baby cannot be born vaginally; would have to go through placenta
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13
Q

What is the presentation of placenta previa?

A
  • Antenatal, painless vaginal bleeding
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14
Q

Describe abnormally “deep” implantation

  • Prevents what
  • Occurs where
A
  • Abnormal implantation prevents spontaneous separation of the placenta
  • Occurs in areas of deficient or absent decidua (endometrium)
  • Lower uterine segment or cervix
  • Cornu of uterus where fallopian tubes insert
  • Overlying scars, (previous c-section, myomectomy)
  • Leiomyoma
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15
Q

What is placentra creta describing? Classes?

A

How much all/part of the placenta attaches abnormally to the myometrium

  • Accreta: onto myometrium
  • Increta: into myometrium
  • Percreta: through myometrium
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16
Q

What is seen here?

A
  • Accreta: onto myometrium
  • Increta: into myometrium
  • Percreta: through myometrium
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17
Q

Describe uterine rupture

  • Prevalence
  • __% occur after ____
  • Mgmt/treatment
  • Location
  • Mortality risk
A
  • 1/800-3,000 deliveries
  • 20% occur after prior c-section
  • 1/17,000-20,000 unscarred uterus
  • Many need post partum hysterectomy to control bleeding
  • >90% occur in lower uterine segment and frequently involves the cervix
  • 50% perinatal mortality
  • 4% maternal mortality
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18
Q

Describe the hemochorial placenta

A
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19
Q

What is seen here?

A

Basal plate of placenta with maternal vessels (at implantation site)

  • 100 arteries and 50-200 veins
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20
Q

Describe the maternal intervillous space

  • Timeline
  • Blood volume
A
  • Maternal arteries and veins directly enter the intervillous space after 8 weeks gestation
  • The intervillous space will contain 400-500 ml of maternal blood in vivo
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21
Q

What becomes the umbilical cord? When?

A

The body stalk becomes the umbilical cord by the 7th post menstrual week

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22
Q

What are complications of short/long umbilical cords?

A
  • Short cords (under 30-35 cm) are problematic at delivery; may reflect poor fetal movement
  • Long cords (>70-100 cm) may cause increased cord accidents (be compressed, cause strangulation…)
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23
Q

Describe umbilical cord insertion issues

A
  • If inserts at periphery, it’s more prone to compression (markedly eccentric cords)
  • Velamentous: cord has vessels unprotected by placental disc; easily ruptured (baby will bleed out)
24
Q

What is Velamentous insertion

  • Incidence
  • Risks
A
  • Incidence 0.5-1% of deliveries
  • Increased risk for thrombosis or rupture of the unprotected vessels
  • Ruptured vessel can result in fetal exsanguination in 3 minutes
25
Q

Describe umbilical cord spiraling

  • Benefits
  • Degree/direction
  • Problems causing increased/decreased spiraling
A
  • Coiling prevents kinking
  • 7:1 left (counter-clock-wise)
  • Absent or decreased spiraling
  • Single umbilical artery, fetal growth problems, aneuploidy, diabetes
  • Increased spiraling
  • Diabetes, preeclampsia, growth restriction, torsion, stricture, intrauterine fetal demise
26
Q

Describe the umbilical vessels (typically)

  • Number
  • Associations
A
  • Normally have two arteries and one vein
  • Single artery occurs in 1% of all deliveries
  • 20% associated with malformations
  • Risk for poor fetal growth and may have intolerance of labor
27
Q

What is seen here?

A

Umbilical cord (with vessels)- single artery?

28
Q

Describe the umbilical vessels themselves

A
  • Large muscular arteries
  • Thin walled vein with internal elastic lamina
  • No vasa vasorum
  • No peripheral nerves
29
Q

What are chorionic plate vessels? Describe them

A
  • Each umbilical artery produces 8+ branches
  • Arteries always cross over veins on placental surface
30
Q

What is seen here?

A

Villi

31
Q

What are the derivatives of the trophoblast? Cells within each?

A

Cytotrophoblast

  • Progenitor cell

Syncytiotrophoblast

  • Terminal cell, acts as both epithelium and endothelium
32
Q

What is the intermediate or invasive trophoblast?

  • What does it invade
A
  • Implantation site
  • Invades through the decidualized endometrium
  • Invades into the inner 1/3rd of myometrium
  • Invades into and through the maternal spiral arteries and adapts the vessels for pregnancy
33
Q

Describe the fetal:placenta weight ratio

A

Fetus should be 7-8x placenta (?)

34
Q

Describe villous maturation

A
35
Q

What is seen in fetal membranes in 1st vs. 3rd trimester in regard to villi/membranes?

A

1st TM

  • Villi just on implantation side

3rd TM

  • Should not see any villi in membranes
36
Q

Describe the layers of amnion and chorion and the role of the maternal decidua

A
  • Amnion has 5 distinct layers, but is only 0.02-0.5 mm thick
  • Chorion has 4 layers and measures 0.1-1.5 mm thick
  • Maternal decidua interfaces with free membranes
37
Q

What is the greatest risk to multiple gestations?

A

Prematurity

38
Q

Which have more problems: dizygotic or monozygotic twins?

A

Monozygotic

39
Q

Describe the placenta situation with twins

A
  • Two ova will produce two separate placentas; although they may be so close together and fused as to look like one
  • Single ovum will produce a variety of twin placentas depending upon when the blastocyst divides
  • The later the division the more one-like the placentas
40
Q

What are the types of placenta situations with twins?

A
  • Dizygotic twins are dichorionic and diamniotic (72%)
  • Monozygotic twins may be:
  • Dichorionic and diamniotic (8%)
  • Monochorionic and diamniotic or monoamniotic (20%)
41
Q

What is seen here?

A

Dichorionic diamniotic setup

42
Q

What is seen here?

A

Monochorionic diamniotic setup

43
Q

What is twin-transfusion syndrome?

A
  • Unequal blood flow between monochorionic twins (7-30%)
  • Donor twin shunts blood away, results in anemia growth restriction, oligohydramnios
  • Recipient twin gets too much blood, results in polycythemia and cardiac overload, polyhydramnios
44
Q

What is seen here?

A

Monochorionic monoamniotic setup

45
Q

Conjoined twins happen when?

A

Blastocyst divides after 13 days

46
Q

Describe pregnancy induced HTN (preeclampsia-eclampsia)

  • Incidence
  • More common when
  • Symptoms
  • Etiology
A
  • 6% of pregnancies
  • More common in first pregnancy
  • More common in early and later reproductive years

Sx: hypertension and proteinuria (with or without edema)

Etiology: not completely understood

  • Genetics, inflammatory cytokines
  • Placental abnormalities
47
Q

What is something that may occur involving abnormal maternal vessels with preeclampsia/eclampsia?

A
  • Failure of conversion of maternal spiral arteries from a low volume-high resistance system to a high volume-low resistance system
  • Atheroma classic pathologic change
48
Q

What placnetal changes occur in preeclampsia?

A
  • Small placenta
  • Infarcts: multiple, large and different ages
  • Accelerated villus maturation and exaggerated syncytial knots
49
Q

What is seen here?

A

Accelerated villus maturation and exaggerated syncytial knots

50
Q

What is abruptio placenta (diagnosis)?

A

(Premature detachment/rupture of placenta?)

Clinical diagnosis with 2+ of the following:

  • Antepartum hemorrhage after 20 wks (vaginal bleeding or concealed)
  • Retroplacental hematoma (detaching placenta)
  • Uterine pain or tenderness (no relaxation between contractions)
  • Fetal distress or death
51
Q

What is seen here?

A

Abruptio placenta

52
Q

Describe gestational diabetes

  • Incidence
  • Risk factors
  • Screening when
  • Increased risk of what
A
  • 3-10% of pregnancies
  • Risk factors: excessive maternal weight gain, obesity, family history, advanced maternal age
  • Screening 24-28 weeks
  • Increased risk for development of insulin dependent diabetes later in life
53
Q

Describe the pathogenesis and consequences of gestational diabetes

A

Maternal hyperglycemia results in large amount of glucose that crosses placenta

  • Fetal overgrowth, macrosomia
  • Cardiomyopathy

Fetus produces too much insulin

  • Hypoglycemia at birth once maternal source of glucose is gone
  • Increased risk for respiratory distress
54
Q

What is seen here?

A

Features of placenta associated with diabetes

  • Huge placenta (top left)
  • Villi look completely different (top right)
  • Bigger, really round; many vessels within stroma
  • Look more immature (vs. preeclampsia/HTN condition that has accelerated maturation)
  • Increased risk of thrombosis (bottom right)
55
Q

What is seen here?

A

Infant of diabetic mother

  • Pancreatic changes (large islets?) (top)
  • Cardiac hypertrophy (bottom)
56
Q

Infant of diabetic mother has what features/risks?

A
  • Risk of morbidity and mortality increases with poor glucose control, higher in insulin dependent diabetics
  • Trauma at delivery, shoulder dystocia
  • Increased c-section
  • Increased in utero fetal demise after 36 week
  • Increased congenital malformations
  • Increased hemoglobin, hyperbilirubinemia and thromboses

a_GYNGU (17 decks)

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