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Placenta. By Joshua Bower Peer Support 2013/2014 [email protected]. Learning Outcomes. Placenta Understand how the placenta forms and grows Know how the structure of the placenta is linked to its functions Know in principle the main functions of the placenta - PowerPoint PPT Presentation
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• Placenta– Understand how the placenta forms and grows– Know how the structure of the placenta is linked to
its functions– Know in principle the main functions of the
placenta– Know in principle some of the main problems
related to placental dysfunction• Pre-eclampsia
– Relate maternal adaptations in pregnancy to some common complications of pregnancy including pre-eclampsia and gestational diabetes
Learning Outcomes
TRUE or FALSE?TRUE or FALSE?The embryo implants into the uterine endometrium around day 7.
• Anchor the placenta• Establish the chorionic villus• Establish maternal/foetal blood
flow within the placenta
What are the THREE aims of implantation? [3]
• Thinning of placental barrier• Margination of foetal vessels• Massive expansion of surface area by arborisation
How does the chorionic villus adapt to meet the expanding need of the developing foetus? [3]
TRUE or FALSE?TRUE or FALSE?There are 2 umbilical veins and 1 umbilical artery.
TRUE or FALSE?TRUE or FALSE?Maternal-foetal blood flow is low pressure with a low flow rate.
• Endocrine (produce steroid and peptide hormones)
• Transfer (nutrition, waste, gas exchange)• Immunity
What are the THREE functions of the placenta? [3]
Which of the following is measured in a pregnancy test?
FSH
LHOestradiol
hPLhCG
Testosterone
TRUE or FALSE?TRUE or FALSE?hCG and hPL are peptide hormones
• (i) 10-12 weeks• (ii) Levels rise steadily during
pregnancy
When do (i) hCG and (ii) hPL levels peak?
• hCG maintains the corpus luteum
• The corpus luteum produces progesterone, which maintains a viable endometrium, until the placenta takes over
What is the function of hCG, and why is this important?
H2O
Glucose
Immunoglobulins
Amino acids
Alcohol
Passive diffusion
Receptor-mediated pinocytosis
Passive diffusion
Facilitated diffusion
Active transport
Which molecule uses each transfer mechanism?
TRUE or FALSE?TRUE or FALSE?IgM can cross the placental barrier
It is IgG which can
What effect does hCG have on maternal IgA, IgG and IgM? Why?
Reduces levelsHumoral immune depression to prevent
rejection of the placenta by the mum, and vice versa
Makes mother more susceptible to viruses
Placenta Problems
What term is used to denote a low-lying placenta?
Placenta praevia
A pregnant woman of 8 months presents with significant PV bleeding. What may have happened?
Placental abruption
• Uncontrolled invasion of the placenta …
• Accreta – …into part of myometrium• Increta – …into whole myometrium• Percreta – …beyond myometrium into uterine
serosa, and thus can atttach to the bladder or rectum
What is placenta accreta, increta and percreta?
• Failure of the placenta and uterus to separate
• The placenta maintains uterine blood supply, causing PV bleeding
• Treatment – “extraction” of the placental tissue
What is post-partum haemorrhage, and what is the treatment?
• Choriocarcinoma
What is a malignant gestational trophoblastic tumour called?
• Hydatidiform mole– Where a non-viable
egg implants in the uterus
– It is a gestational trophoblastic disease
What is another name for a molar pregnancy?
• Hydatidiform moles usually have high levels of hCG
• In ectopic pregnancies, hCG levels are low
How can you differentiate a hydatidiform mole from an ectopic pregnancy?
• Intra-uterine growth restriction (IUGR)
What term describes when the placenta compensation cannot meet the needs of the foetus?
To finish…
A pregnant lady presents to A+E with swollen hands and face. Examination reveals she is hypertensive with proteinuria. Diagnosis?
Pre-eclampsia
Oedema
Proteinuria
Hypertension
• Caused by abnormal placentation (development and arrangement of the placenta) or abnormal placental function
• Proposed mechanism:• Reduced uterine-placental blood flow results in
placental ischaemia, leading to release of factors causing endothelial dysfunction (e.g. TNF-alpha, IL-6), reduced NO and increased ROS
• This in turn leads to altered renal function, increased TPR and ultimately hypertension
What is pre-eclampsia?
• Acute and life-threatening tonic-clonic seizures in pregnancy
What is eclampsia?
What is placentophagia*?
• * Won’t be examined**• ** …probably
