Placenta and Intra-Uterine Growth Restriction Flashcards
1
Q
Fertilization and beyond - Summary
- Sperm and Ovum meet in … Tube (… Tube) (usually a…) …-… hours after ovulation.
- Fusion occurs and 2nd … division occurs
- … reaction makes ovum impermeable to other sperm
- End- Zygote- has … (46 chromosomes)
A
- Sperm and Ovum meet in Fallopian Tube (Uterine Tube) (usually ampulla) 12-24 hours after ovulation.
- Fusion occurs and 2nd meiotic division occurs
- Acrosome reaction makes ovum impermeable to other sperm
- End- Zygote- has diploid (46 chromosomes)
2
Q
Zygote to Blastomere
- Zygote = A … … cell.
- The process of … is the step of embryogenesis where the zygote divides to produce a cluster of cells known as the …
- The … forms early in embryonic development and has two layers that form the embryo and placenta.
A
- Zygote = A fertilised egg cell.
- (The fertilized egg, known as a zygote, then moves toward the uterus, a journey that can take up to a week to complete until implantation occurs. Through fertilization, the egg is activated to begin its developmental process (progressing through meiosis II), and the haploid nuclei of the two gametes come together to form the genome of a new diploid organism.)
- The process of cleavage is the step of embryogenesis where the zygote divides to produce a cluster of cells known as the morula.
- morula: A spherical mass of blastomeres that forms following the splitting of a zygote; it becomes the blastula.
- The blastocyst forms early in embryonic development and has two layers that form the embryo and placenta.
- The human blastocyst possesses an inner cell mass (ICM), or embryoblast, which subsequently forms the embryo, and an outer layer of cells, or trophoblast, which later forms the placenta.
3
Q
Morula = A spherical mass of … that forms following the splitting of a …; it becomes the blastula.
A
Morula = A spherical mass of blastomeres that forms following the splitting of a zygote; it becomes the blastula.
4
Q
Morula -> Blastocyst
- In humans, the blastocyst is formed approximatelyy … days after fertilization.
- This stage is preceded by the morula.
- The morula is a solid ball of about … undifferentiated, spherical cells.
- As cell division continues in the morula, the blastomeres change their shape and tightly align themselves against each other.
- This is called compaction and is likely mediated by cell surface adhesion glycoproteins.
A
- In humans, the blastocyst is formed approximatelyy four days after fertilization.
- This stage is preceded by the morula.
- The morula is a solid ball of about 16 undifferentiated, spherical cells.
- As cell division continues in the morula, the blastomeres change their shape and tightly align themselves against each other.
- This is called compaction and is likely mediated by cell surface adhesion glycoproteins.
5
Q
Blastocyst
- The blastocyst possesses an inner cell mass (ICM), or …, which subsequently forms the embryo, and an outer layer of cells, or …, which later forms the p….
- The … surrounds the inner cell mass and a fluid-filled, blastocyst cavity known as the blastocoele or the blastocystic cavity.
A
- The blastocyst possesses an inner cell mass (ICM), or embryoblast, which subsequently forms the embryo, and an outer layer of cells, or trophoblast, which later forms the placenta.
- The trophoblast surrounds the inner cell mass and a fluid-filled, blastocyst cavity known as the blastocoele or the blastocystic cavity.
6
Q
Days 4-5 Fertilization
- The morula develops a cavity and becomes known as a …
- This thins out and becomes the … –start of the placenta
- The rest of the cells move (are pushed up) to form the inner cell mass. This creates an embryonic …
- The … has now reached the uterine lumen and is ready for implantation.
A
- The morula develops a cavity and becomes known as a blastocyst.
- Blastocyst thins out and becomes the trophoblast –start of the placenta
- The rest of the cells move (are pushed up) to form the inner cell mass. This creates an embryonic pole.
- The blastocyst has now reached the uterine lumen and is ready for implantation.
7
Q
Day 6-7 Bilaminar disc of the embryo
- Inner cell mass differentiates into two layers: E…(1) and H…(2)
- These two layers are in contact.
- (2) forms extraembryonic membranes and the primary … …
- (1) forms embryo
- … cavity develops within the epiblast mass
A
- Inner cell mass differentiates into two layers: epiblast and hypoblast.
- These two layers are in contact.
- Hypoblast forms extraembryonic membranes and the primary yolk sac
- Epiblast forms embryo
- Amniotic cavity develops within the epiblast mass
8
Q
Days 16 + Fertilization
- Bilaminar disc develops further by forming 3 distinct layers (this process is known as …)
- Initiated by … streak.
- The epiblast becomes known as …
- The hypoblast is replaced by cells from the epiblast and becomes …
- The epiblast gives rise to the third layer the …
A
- Bilaminar disc develops further by forming 3 distinct layers (this process is known as gastrulation)
- Initiated by primitive streak.
- The epiblast becomes known as ectoderm
- The hypoblast is replaced by cells from the epiblast and becomes endoderm
- The epiblast gives rise to the third layer the mesoderm.
9
Q
Embryo – the 3 germ layers
- The … degenerates. The … gives rise to all three germ layers.
- The embryo … to create the adult pattern
A
- The hypoblast degenerates. The epiblast gives rise to all three germ layers.
- The embryo folds to create the adult pattern
10
Q
The development / formation of the placenta
- The … cell mass - called the … - makes the placenta
- S.. cells invade devidua (endometrium)
- C… cells erodes maternal spiral arteries and veins
- Spaces (L…) between the fill up with maternal blood
- Followed by mesoderm that develops into fetal vessels
- Aiding the transfer of nutrients, O2, across a simple cellular barrier
A
- The outer cell mass - called the trophoblast - makes the placenta
- Syncytiotrophoblast cells invade devidua (endometrium)
- Cytotrophoblast cells erodes maternal spiral arteries and veins
- Spaces (lucanae) between the fill up with maternal blood
- Followed by mesoderm that develops into fetal vessels
- Aiding the transfer of nutrients, O2, across a simple cellular barrier
11
Q
Placenta formation
A
- Top - what should happen
- Bottom - pre-eclampsia and growth restriction (more narrow artery - higher resistance)
12
Q
Cytotrophoblast cells (CTB)
- … stem cells
- Invade the … blood vessels and destroy the epithelium
- Give rise to the … cells (STB)
- … in number as pregnancy advances
A
- Undifferentiated stem cells
- Invade the maternal blood vessels and destroy the epithelium
- Give rise to the syncytiotrophoblast cells (STB)
- Reduce in number as pregnancy advances
13
Q
Syncytiotrophoblast cells (STB)
- … differentiated cells
- … contact with maternal blood
- Produce … hormones
A
- Fully differentiated cells
- Direct contact with maternal blood
- Produce placental hormones
14
Q
The Placenta as an Endocrine Organ
- What two hormones? (… and …)
- What do they help to do?
- 1 = maintenance of … and produces … and …
- 2 = for growth and …, produces carbohydrate and …
A
-
1 = Human chorionic gonadotrophin (HCG)
- maintenance of corpus luteum of pregnancy
- produces progesterone and oestrogen
-
2 = Human placental lactogen HPL
- growth, lactation
- carbohydrate and lipid
- Many more!
15
Q
Placental Barrier
- Maternal blood in the la… in direct contact with …
- … layer of syncytiotrophoblast/cytotrophoblast/fetal capillary epithelium is all that separates the fetal and maternal blood
- Cytotrophoblasts … as the pregnancy advances
- The barrier … as pregnancy advances leading to a greater surface area for exchange (over 10m2 )
A
- Maternal blood in the lacunae in direct contact with syncytiotrophoblasts
- Mono layer of syncytiotrophoblast/cytotrophoblast/fetal capillary epithelium is all that separates the fetal and maternal blood
- Cytotrophoblasts decrease as the pregnancy advances (not needed)
- The barrier thins as pregnancy advances leading to a greater surface area for exchange (over 10m2 )
16
Q
Transfer Across the Placenta
- Gases – oxygen and carbon dioxide by simple diffusion
- Water and electrolytes
- …. hormones
- … poor – only by pino…
- Transfer of maternal antibodies Ig.. -starts at …. weeks – mainly after … weeks therefore lack of protection for premature infants
A
- Gases – oxygen and carbon dioxide by simple diffusion
- Water and electrolytes
- Steroid hormones
- Proteins poor – only by pinocytosis
- Transfer of maternal antibodies IgG -starts at 12 weeks – mainly after 34 weeks therefore lack of protection for premature infants
17
Q
Named Parts of the Decidua
A
18
Q
Placenta - Maternal vs Fetal surface
A
19
Q
Umbilical cord insertions
A
usually cord comes out middle but may vary
20
Q
What is Vasa Praevia? (pregnancy)
A
- velomentous cord insertion that runs across the cervical os
- What is vasa previa? Vasa previa is an incredibly rare, but severe, complication of pregnancy.
- The fetal vessels within the umbilical cord pass over the internal os. As the internal os dilates in labour the vessels are stretched and exposed and can rupture leading to massive fetal blood loss and death.
- Diagnosed on Ultrasound using colour dopplers
- Management deliver by Caesarean Section when the fetus is above 34 weeks.
21
Q
Clinical aspects of the placenta
- Position of the placenta within the uterus
- Mainly … (at the top)
- Anterior or posterior (front wall or back wall)
- “low lying” or placenta … (near to the cervical os)
A
- Position of the placenta within the uterus
- Mainly fundal (at the top)
- Anterior or posterior (front wall or back wall)
- “low lying” or placenta praevia (near to the cervical os)
22
Q
- What is Placenta Praevia?
- What can it cause?
A
- “low lying” placenta position (near to the cervical os)
- May lead to
- Massive bleeding in pregnancy
- Painless bleeding
- Fetal death
- Maternal death
23
Q
Clinical aspects of the placenta
- Failure of … invasion into maternal circulation at 12 and 18 weeks
- Poor maternal fetal … of blood
- Lack of oxygen and nutrients to the fetus
- Leads to Fetal … …
- Pre-… (raised Blood Pressure)
A
- Failure of trophoblastic invasion into maternal circulation at 12 and 18 weeks
- Poor maternal fetal mixing of blood
- Lack of oxygen and nutrients to the fetus
- Leads to Fetal Growth Restriction
- Pre-eclampsia (raised Blood Pressure)
24
Q
- What is Placenta Accreta?
- What is the treatment?
A
- Placenta accreta is a serious pregnancy condition that occurs when the placenta grows too deeply into the uterine wall.
- Placenta unable to separate at birth – uterus can not contract down and massive bleeding.
- Treatment hysterectomy.
25
Q
Placenta Accreta
A
The placenta has invaded too deep into the myometrium and thus after birth the placenta can not separate and stays within the uterus. As a consequence the uterus can not contract down and massive bleeding can occur leading to the requirement to do a hysterectomy.
26
Q
Placental abruption
- …. of the placenta during pregnancy.
- Leads to disruption of the … to the fetus leading to fetal distress and death
- Bleeding can be … but the … fills up with blood.
- Different to Placenta praevia where the blood is seen from the vagina.
- Presents as:
- …
- …
- …
- …
A
- Seperation of the placenta during pregnancy.
- Leads to disruption of the blood to the fetus leading to fetal distress and death
- Bleeding can be concealed but the uterus fiills up with blood.
- Different to Placenta praevia where the blood is seen from the vagina.
- Presents as:
- Massive bleeding in pregnancy (often concealed)
- Extremely painful
- Fetal death
- Maternal death
27
Q
Placenta in multiple pregnancies
A
28
Q
Development vs Growth
- When is development? What happens?
- What is growth?
A
- First 12 weeks fetal development occurs – organs formed
- Then the baby needs to get bigger – fetal growth
29
Q
Why do We Monitor Fetal Growth?
-
Growth restriction is associated with
- …
- … death
- … morbidity
A
-
Growth restriction is associated with
- Stillbirth
- Neonatal death
- Perinatal morbidity
36
Q
Types of IUGR
A
Symmetrical or Asymmetrical
39
Q
Trophoblast invasion
A
42
Q
Diagnosis of Fetal Growth Restriction
- Clinical … – abdomen “looks smaller”
- Clinical measurement of uterine size: … - … height (SFH)
A
- Clinical suspicion – abdomen “looks smaller”
- Clinical measurement of uterine size: Symphysis - fundal height (SFH)
44
Q
Fetal Growth charts
A
45
Q
Symmetrical Fetal growth restriction - example graph
- what groups?
- What is reduced?
*
A
- Groups 1 and 2 (small baby due to ethnicity or parents, or non-placental reason)
- In symmetrical growth restriction the Head Circumference, The BPD ( biparietal diameter of the Head() and the abdominal circumference are ALL reduced
46
Q
Asymmetrical Fetal growth restriction - example graph
- What groups?
- What is reduced?
A
- Group 3 - placental mediated GR
- AC - abdominal circumference only dropped off
47
Q
Why is abdominal circumference a good representation of IUGR?
A
Fetal liver is there - liver stores glycogen if good growth - struggling - won’t be able to store any so circumference will be smaller
56
Q
Normal pregnancy middle cerebral artery VS in Fetal growth restriction
A
- left - normal - Pressure difference in systole and diastole usually very big
-
right - FGR - when baby is struggling, difference between top and bottom spike = a lot lower (compensating or not compensating)
- This scan is demostrating the normal blood flow in the middle cerebral artery in the barin.
- The peak corresponds to systole of the heart and during diastole the flow is negative ie below the line.
57
Q
Wait or deliver in Intra-Uterine GR?
- If we wait do to a lower chance of …
- Give … to help
- Reduces need for what route of delivery?
- If baby is more likely to survive, particularly above … weeks - may have to delivery if:
- If there is decreased ….
- Abnormality on the …
- … abnormality
A
- If we wait due to a lower chance of survival
- Give steroids to help
- Reduces need for what route of delivery? - C-section
- If baby is more likely to survive, particularly above 32 weeks - may have to delivery if:
- If there is decreased movements
- Abnormality on the doppler
- CTG abnormality
