The Placenta and Trophoblastic Disease Flashcards
What cells form the placenta?
Trophoblasts (which go on to differentiate into syncytiotrophoblasts and cytotrophoblasts).
The placenta is made up of what cells?
Syncytiotrophoblasts - outer layer
Cytotrophoblasts - inner layer
When does the blastocyst implant into the endometrium?
Day 5
What occurs when the trophoblast cells invade the endometrium?
Invasion causes the decidual reaction causing the decidua to form.
What is the decidua?
The decidua is the modified mucosal lining of the uterus (that is, modified endometrium) that forms in preparation for pregnancy.
What forms fetal capillaries where gas exchange occurs?
Chorionic villi
Umbilical vein
The umbilical vein is a vein present during fetal development that carries oxygenated blood from the placenta into the growing fetus.
Umbilical artery
Carries deoxygenated blood from the fetus to the placenta.
The placenta produces what hormones?
hCG
hPL
Progesterone
What are the respiratory changes that occur in pregnancy?
Increased tidal volume
Increased respiratory rate
Mild respiratory alkalosis
Reduced max inspiratory volume in the third trimester
What are the gastrointestinal changes that occur in pregnancy?
Delayed gut motility
Constipation
Increased alkaline phosphate
What are the renal changes that occur during pregnancy?
Increased blood flow 50% increased GFR Low creatinine and urea Glycosuria is normal Proteinuria (<30mg is normal).
What are the skeletal changes that occur during pregnancy?
Osteopenia
Increased osteoblast activity
Amniotic fluid
Produced by fetal urine, is swallowed and bathes the fetal lungs. 99% water
What can cause a decrease in the amount of amniotic fluid in pregnancy?
IUGR (intrauterine growth restriction).
Renal pathologies
Ruptured membranes
Normally reduces to term
What can cause a increase in the amount of amniotic fluid in pregnancy?
Diabetes
Macrosomia
Fetal pathologies
Macrosomia
The term “fetal macrosomia” is used to describe a newborn who’s significantly larger than average. (Birth weight of more than 8pounds).
What marks the fetal side of the placenta?
The side of the placenta that the umbilical cord is coming out of.
What are the two membranes of the placenta?
Amnion (side to the baby)
Chorion (side to the mum)
B-hCG is homologous with what other hormone?
TSH
B-hCG is produced by what cells of the placenta?
Syncytiotrophoblasts
Explain the anatomy of the umbilical cord.
2 Fetal Arteries
1 Fetal Vein
Wharton’s jelly
Umbilical arteries transfers what?
Deoxygenated blood and waste products from the fetus to the placenta.
Umbilical veins transfer what?
Oxygenated blood and nutrients from the placenta to the fetus.
Spiral arteries supply blood where?
Spiral arteries supply blood to the endometrium of the uterus.
What are the main roles of the placenta?
- Hormone production - hCG, hPL and progesterone.
- Immunological barrier - phagocytes and lymphoid cells.
- Respiration and excretion - glucose, oxygen, AA exchange.
When does the placenta take over the corpus luteum?
Week 12
Wharton’s jelly
Gelatinous substance within the umbilical cord, protecting and insulating it.
- contains macrophages.
Placenta praevia
Low lying placenta
What are the complications of placenta praevia?
Prevents vaginal delivery - risk of bleeding.
> C-section is needed.
Placenta accreta
Placenta accreta is a serious pregnancy condition that occurs when the placenta grows too deeply into the uterine wall.
What are the complications of placenta accreta?
Prevents vaginal delivery - risk of bleeding.
> C-section is needed.
(same as placenta praevia)
What causes gestational trophoblastic disease (GTD)?
To many paternal chromosomes
What is a molar pregnancy/hydatidiform mole?
A molar pregnancy, also called a hydatidiform mole, is one where an abnormal fertilised egg implants in the uterus (womb). The cells that should become the placenta grow far too quickly and take over the space where the embryo would normally develop.
What is meant by hydatidiform mole?
Hydatidiform mole means fluid filled mass of cells.
What are the risk factors of molar pregnancy?
Extremes of ages (<18 or 40
What is meant by a complete molar pregnancy?
The fertilisation of an empty egg (so there are no maternal genes at all). This results in no embryo, and trophoblastic hyperplasia.
How does a complete molar pregnancy present on an ultrasound scan?
The placental villi becomes swollen forming vesicles and so appear as a bunch of swollen grapes.
A complete molar pregnancy is haploid, diploid or triploidy?
Diploid
A partial molar pregnancy is haploid, diploid or triploidy?
Triploidy
What is meant by a partial molar pregnancy?
A normal egg is fertilised by either two sperm or one sperm that duplicates it’s DNA.
> an abnormal embryo can develop that is triploidy, leading to trophoblastic hyperplasia.
How does a partial molar pregnancy present on an ultrasound scan?
Again bunches of grapes however these appear more scattered.
Placenta choriocarcinoma
A malignant trophoblastic tumour
When do placenta choriocarcinomas occur?
50% occur after a molar pregnancy
30% occur after normal pregnancy
20% occur after miscarriage
What is the prognosis of a placental choriocarcinoma?
Placental choriocarcinoma’s are usually very well treated and prognosis is very good, they are just hard to diagnose.
GTN
Gestational trophoblastic neoplasia (placental choriocarcinoma)
Is Gestational trophoblastic neoplasia malignant or benign?
Malignant
What hormone is elevated in GTN?
beta-hCG
What are the signs of a complete molar pregnancy?
Missed periods
Positive pregnancy test due to excess beta-hCG produced.
Vaginal bleeding
