L19 - Placenta and Trophoblastic disease Flashcards
1. Discuss normal anatomical and histological structure of the placenta and umbilical cord 2. Describe the release of bHCG from the placenta and where it is released from 3. Describe abnormalities of placentation and their clinical correlates 4. Define gestational trophoblastic disease (partial and complete molar pregnancy) and differentiate this from gestational trophoblastic neoplasia 5. Discuss the epidemiology, risk factors, common clinical features, hCG and follow up of molar pregnancy.
Approximate which day the blastocyst will move into the uterine cavity?
Day 4 - 5
Will then implant into endometrium.
When does the blastocyst implant into the endometrium?
Day 5.
Describe the decidual reaction?
Trophoblast invades endometrium changing it into a decidua.
Describe some roles of Decidualization?
- Promoting placenta formation between a mother and her fetus by mediating invasiveness of trophoblast cells.
- triggers production of factors resulting in structural changes or remodelling (e.g. of maternal spiral arteries)
Describe spiral arteries?
- Low resistance vessels in uterus.
- Temporarily supply blood to endometrium of uterus
- during luteal phase.
What are the two layers that the trophoblast will differentiate into?
- Cytotrophoblst
- cellular trophoblast - Synctiotrophoblast
- expanding peripheral syncytial layer
What occurs during the second week in embryology?
Embryoblast splits:
- Epiblast
- Hypoblast
Trophoblast gives rise to tissues:
- cytotrophoblast
- syncytiotrophoblast
Describe lacunae?
Form from day 7.
- Empty gap
- will fuse with spiral arteries
- and then fill with maternal blood.
- This will bathe the fetus.
State some roles of the placenta?
- Hormone production
- hCG, hPL, progesterone - Immunological barrier
- phagocytes and lymphoid cells - Respiration and excretion
- glucose, oxygen, AA exchange
Role of umbilical arteries
Move deoxyblood from fetus to placenta
Role of umbilical vein
Bring nutrient and oxyblood from placental villi (via umbilical cord) to the embryo.
Describe the structure of the placenta?
- Limited by amniotic membrane on fetal side
- and the basal plate on the maternal side.
Describe some respiratory changes that occur during pregnancy?
- Increased tidal volume
- Increased respiratory rate
- Mild respiratory alkalosis
- Reduced max inspiratory volume in third trimester
What are some gastrointestinal changes that occur during pregnancy?
- Delayed gut motility
- Constipation
- Increased alkaline phosphatase
What are some renal changes that occur during pregnancy?
- 60% increased BF
- 50% increased GFR
- Low creatinine, urea
- Glycosuria is normal
- Proteinuria ,30mg is normal
What are some skeletal changes that occur during pregnancy?
- Osteopenia
- Increased osteoblastic activity
Osteopenia
Bones are weaker than they used to be.
However not weak enough to be diagnosed with osteoporosis.
What week does fetal skin become impermeable?
16 weeks
Describe b-hCG?
Beta subunit picked up in pregnancy test, excreted in urine.
Similar structure to TSH.
When does the placenta take over from the corpus luteum?
12 weeks
Describe the anatomy of the cord? (3)
- Fetal arteries 2
- transfer deoxy blood and waste from fetus to placenta - Fetal vein 1
- transfer oxy blood from placenta to fetus - Wharton’s Jelly
- contains macrophages
- protects and insulates
- makes sure vessels aren’t squished
What is Placenta Praevia?
Low lying placenta.
Covers internal Os.
Prevents vaginal delivery .
May cause bleeding.
What is Placenta accreta?
- Placenta grows too deeply into uterine wall
- may remain attached after delivery
- causing severe blood loss.
High risk complication!
Placenta increta
Placenta invades muscles of uterus
Placenta percreta
Placenta invades uterine wall
Summarise gestational trophoblastic disease?
Group of rare diseases: abnormal trophoblast cells grow inside uterus after conception.
What kinds of diseases are included in gestational trophoblastic disease?
Hydatidiform moles
- complete, partial
Gestational trophoblastic neoplasia
- invasive moles
- choriocarcinomas
Choriocarcinoma
Malignant, fast growing.
Develops from trophoblastic cells .
Can spread through blood to other organs, esp. lungs.
Complete hydatidifrom mole
Egg does not contain mothers DNA. Egg is then fertilised, excess of paternal genes.
46 XX or 46 XY
Trophoblastic hyperplasia.
Partial Hydatidiform moles
Egg normal. However there are two sets of DNA from the father in the fertilized egg.
Abnormal embryo can develop (triploidy) 69 XXY or 92 DDDY
Compare the appearance of complete and partial hydatidiform moles?
Complete:
- placental villi become swollen like a bunch of grapes.
Partial
- Clusters of grapes are more scattered
- more commob
Describe the prognosis of a choriocarcinoma?
Risk scored with the FIGO scoring system.
Management determined by high or low risk.
score of <6 has a 100% cure rate.
What is a key feature of GTD?
Increased bhCG release.
