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Obstetrics And Gynaecology > Placenta > Flashcards

Placenta Flashcards

1
Q

Types of placenta

A
  1. Discoidal
  2. Hemochorial
  3. Deciduate
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2
Q

Placenta is formed by

A

Fetal side: Chorion frondosum
Maternal side: Decidua basalis

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3
Q

Duration of formation of placenta

A

Begins by 6 weeks
Ends at:
1. Anatomically: 16 weeks
2. Physiologically: Till term

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4
Q

Weight at term

A

500 g

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5
Q

Diameter of placenta

A

15-20/22 cm

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6
Q

Thickness of placenta

A

Normal: 2.5 cm
>4 cm: Placentomegaly

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7
Q

Causes of placentomegaly

A
  1. Fetal anemia
  2. Hydrops Fetalis
  3. Maternal diabetes
  4. Molar pregnancy esp partial mole
  5. Intrauterine infections (Syphilis>CMV)
  6. Chorangioma and Placental mesenchymal dysplasia
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8
Q

Causes of small placenta

A
  1. Uteroplacental insufficiency(PIH, high maternal BP)
  2. IUGR
  3. Constitutionally small baby
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9
Q

Normal attachment of placenta

A

Upper uterine segment

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10
Q

Placenta in lower uterine segment and within 2 cm of int os

A

Low lying placenta

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11
Q

Placenta is in lower uterine segment and edge touches or covers int os

A

Placenta previa

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12
Q

Best time to do USG to localize placenta

A

3rd trimester
Why: Because of migration

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13
Q

Fetal side is also known as

A

Chorionic plate
Why: Develops from chorion frondosum

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14
Q

Maternal side is also known as

A

Basal plate
Why: Develops from decidua basalis

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15
Q

Membrane and cord attached at what side?

A

Fetal side

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16
Q

Colour of Fetal side

A

Shiny, grey in colour

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17
Q

Colour of maternal side

A

Dull,red/maroon in colour

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18
Q

Composition of placenta

A

Fetal side: 4/5th of placenta
Maternal side: 1/5th of placenta

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19
Q

Types of villi

A
  1. Primary
  2. Secondary
  3. Tertiary
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20
Q

Composition of primary villi and formation

A

Trophoblastic shell
D13 after fertilisation

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21
Q

Composition of secondary villi and formation

A

Trophoblastic shell+Mesodermal core
D16 after fertilisation

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22
Q

Composition of tertiary villi and formation

A

Trophoblastic shell+Mesodermal core+Fetal blood vessels
D17 after fertilisation

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23
Q

Structures separating maternal from Fetal blood (outside to inside)

A
  1. Syncytiotrophoblast
  2. Cytotrophoblast
  3. Extra amniotic mesoderm
  4. Fetal capillary endothelium
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24
Q

Volume of maternal and Fetal blood

A

M: 150 ml
F: 350 ml
Total: 500 ml

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25
Types of placental circulation
1. Uteroplacental (Maternal) 2. Fetoplacental (Fetal)
26
Uteroplacental circulation is via
Spiral arteries (100-120)
27
Uteroplacental circulation at term
500-750 ml/min
28
Fetoplacental circulation is via
Oxygenated blood: Umbilical vein (placenta to fetus) Deoxygenated blood: Umbilical artery (fetus to placenta)
29
Fetoplacental blood flow at term
400 ml/min
30
Uterine and Fetal blood flow at term
U: 750 ml/min F: 125 ml/min
31
Methods of placental separation
1. Central separation/ Schultz method 2. Peripheral separation/ Duncan method
32
Schultz method (Central) starts from
Center
33
Duncan method (Peripheral) starts from
Margin/Periphery
34
Formation of retroplacental clot
S: yes D: no
35
Which side comes out first?
S: Fetal side D: Maternal side
36
Functions of placenta
1. Metabolic function 2. Endocrine function: Production of hormones 3. Transfer of substrates to the fetus and exchange of gases
37
Metabolic functions
1. Glucose: >Main source of energy >Transfer via facilitated diffusion (GLUT receptors 1,3) >Fetus dependant for glucose from mother >Main enzyme: Glycogenin 2. Fatty acid: >Used to form cholesterol >Maternal triglycerides broken into fatty acids and transferred to fetus 3. Amino acid >Placental protein production: 1.5 g/day (1st trimester) 7.5 g/day (3rd trimester) 4. Waste product: >Lactate transferred to mother
38
Hormones produced
1. Steroid hormones: >estrogen, progesterone, corticosteroids 2. Peptide hormones: >hCG, HPL,CRH,IGF,VEGF, PLGF, and Tyrosine Kinase 1
39
HCG produced from
Syncytiotrophoblast
40
Type of protein in HCG
Glycoprotein hormone (Max carb content)
41
Subunits of HCG
2 subunits: 1. Alpha subunit: Chr. 6, non specific (common in LH, FSH, TSH) 2. Beta subunit: Chr. 19, specific
42
Applied aspect of HCG
1. Pregnancy test: Beta subunit assessed 2. In IVF as ovulation trigger, inj. HCG used: HCG is morphologically similar to LH, FSH, TSH
43
Detection of HCG
Earliest in serum by 8 days after fertilisation/D 22 of cycle/5-6 days before missed periods
44
Most sensitive test to detect HCG
Serum quantitative tests: Fluorescent immunoassay(FIA)>Radioimmunoassay(RIA) Relevant only in 1st trimester and not beyond this
45
Max levels of HCG seen in
10 weeks (60-80 days)
46
Min levels of HCG seen in
16 weeks (16-20 weeks)
47
Applied aspects to rise in HCG
D1 to D3 if HCG inc by 33-65%: Viable intrauterine pregnancy D1 to D3 if HCG inc by <33-65%: Slow rise ectopic pregnancy D1 to D3 if HCG dec: Dying/non viable intrauterine
48
Causes of HCG higher than expected
1. Wrong dates 2. Multifetal pregnancy 3. Rh negative pregnancy 4. Molar pregnancy 5. Down’s syndrome
49
Causes of HCG lower than expected
1. Wrong dates 2. Abortion 3. Ectopic pregnancy 4. Trisomy other than Down’s syndrome
50
Functions of HCG
1. Maintains corpus luteum in pregnancy 2. 1st stimulus for testosterone release from Leydig cells in male fetus 3. Smooth muscle relaxant 4. Prevents rejection of fetus
51
Clearance of HCG
Liver: 70% Kidney: 30%
52
HPL formed by
Syncytiotrophoblast
53
Type of protein in HPL
Single non glycosylated polypeptide chain
54
HPL structurally similar to
GH and prolactin
55
Detection of HPL
Earliest by 3 weeks of pregnancy Peaks at 34-36 weeks (3rd trimester)
56
Maximal HPL secretion seen in
Maternal plasma>Amniotic fluid>Fetal blood
57
Functions of HPL
Provide glucose to fetus: Promotes lipolysis (used by mother for energy and glucose spared for fetus)
58
IGF produced by
Placenta
59
Action of IGF-2
Binds to IGF-1 and leads to Fetal growth
60
Applied aspect of CRH
Acts as placental clock: Maternal stress (anxiety, depression) cause inc in placental CRH leading to preterm labor
61
VEGF and PLGF are formed by
Villous trophoblast
62
Role of VEGF and PLGF
VEGF: Angiogenesis in early pregnancy (T1) PLGF: Angiogenesis in late pregnancy. (T3)
63
Conditions with inc estrogen
1. Erythroblastosis fetalis 2. Maternal androgen producing tumor
64
Conditions with dec estrogen
1. Intrauterine Fetal demise 2. Anencephaly 3. Placenta lacks sulfatase/aromatase 4. Down syndrome
65
Action of Tyrosine Kinase 1
Prevents angiogenesis and inhibits vasodilatory effects of VEGF, PLGF
66
Tyrosine kinase on Pre-eclampsia
Inc levels lead to no angiogenesis or vasodilatory effects and cause vasoconstriction leading to pre-eclampsia
67
Placenta anomalies
1. Placenta succenturiate 2. Placenta bilobata 3. Placenta multilobata 4. Placenta spuria 5. Placenta membranacea 6. Fenestrated placenta 7. Circumvalate and circummarginate placenta 8. Placenta accreta spectrum
68
What is Placenta succenturiate?
Small lobe of placenta separated from main placenta and connected by blood vessels
69
What is Placenta bilobata?
2 equal lobes of placenta separated from each other and umbilical cord supplying blood
70
Complications of Placenta bilobata
1. Placenta previa 2. Vasa previa
71
What is Placenta succenturiata?
Small part of placenta lie in lower uterine segment leading to placenta previa
72
What is Placenta spuria?
Small part of placenta separates from main placenta and not connected by any blood vessels
73
What is Membranous placenta?
Thin placenta covers entires uterus. Villi present throughout uterus
74
Complications of Membranous placenta
1. 2nd trimester abortions 2. Preterm labour 3. APH 4. PPH
75
What is Fenestrated placenta?
Part of placenta absent
76
Types of extrachorial placenta
1. Circumvalate placenta 2. Circummarginate placenta
77
What is Circumvalate placenta?
Basal (Maternal) plate is bigger d/t Fetal membranes which forms extra curves or folds. Valve like folding of chorion and amnion seen
78
What is Circummarginate placenta?
Basal plate surround chorionic plate in form of ring. Basal plate bigger d/t fibrin+clots
79
Complications of extrachorial placenta
1. Abruptio placentae 2. Preterm labour 3. Fetal growth restriction

Obstetrics And Gynaecology (10 decks)

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