The placenta Flashcards
Roles of placenta
Foetal lungs/kidneys/GI tract
Protection
Hormones
2 parts of blastocyst
Inner cell mass - baby
Trophoblast - placenta
Syncytiotrophoblast
Direct contact with maternal blood
Outer layer of multiple fused trophoblast cells (specialised systems for maternal to fetal transport, barrier to unwanted material and hormone secretion)
Cytotrophoblast
Inner layer with several specialised functions: proteolytic enzyme secretions (acts on decidua), endometrial invasion, villous formation, angiogenesis
Blood supply to uterus
Aorta - internal iliac - uterine - ovarian - arcuate - radial - basal - spinal
How do uterine blood vessels change in pregnancy?
As pregnancy develops, spiral arteries funnel, generating a wider outflow into the intervillous space
Arteries to placenta
2, deoxygenated
Veins to placenta
1, oxygenated
Protrusions of placenta
Cotyledon
hCG in pregnancy
Produced from blastocyst
Support pregnancy in 1st trimester - CL
Progesterone in pregnancy
Placenta from 12 weeks
Human placental lactose
Anti-insulin = more glucose for foetus
O2 transfer from mother
Small right shift = O2 unloading
O2 transfer to foetus
Left shift = O2 uptake
Placental barrier
Microbiological safety barrier
Less efficient in early pregnancy
Maternal antibodies = immune protection
Why doesn’t the mum attack baby
Phosphocholine secreted by placenta
Suppression of cytotoxic T cells
Which pregnancy does Rhesus affect mother?
Second
Which antibodies are ABO?
IgM - doesn’t cross placenta
RhD antibodies
IgG
Can RhD antibodies cross placenta?
Yes, they are small
If Rh+ and Rh- parents have baby will it be + or -
+ve
What is given to Rh-ve mothers?
Anti-D in pregnancy
When is Rh -ve mother given anti-D?
28/34
Within 72 hours if baby is Rh +ve
Placenta praaevia
Placenta lies across cervical os
Placental abruption
Bleeding between placenta and uterus
Prolapsed cord
Cord bulges through cervix
Pre-eclampsia
Placenta issue in baby and mum
Grade I - grade IV placenta praevia
Grade 1 = none, grade 5 = fully covered
Symptoms of placenta praevia
Bleeding during pregnancy
Painless
Symptoms of placental abruption
Painful
Bleeding can be revealed or concealed
Life-threatening for foetus
Cord prolapse
Membranes rupture
Foetal head compresses cord = umbilical
Maternal symptoms of pre-eclampsia
Hypertension Fluid retention Coagulopathy Renal damageConvulsions Liver damage
Fetal symptoms of pre-eclampsia
Growth retardation
