Intra/post - Multiple pregnancy Flashcards
what % of all pregnancies are twins
2% - (30% of those are identical)
compared to single pregnancies, how does twin perinatal mortality compare (+why?)
perinatal mortality is 5x higher
due to increased incidence of prematurity and congenital abnormalities
what is a zygote
a fertilised egg
how long does it take for a blastocyst to develop
12 days to develop from a zygote to an embryo, then a morula then a blastocyst
how long does it take before the blastocyst implants
14 days
what are monozygotic twins
identical twins from one egg and one sperm - once fertilised the cell divides
what are dizygotic twins
fraternal twins from two sperms and two eggs
what is the chorion
foetal portion of the placenta - provides nutrition
what is the amnion
innermost membrane that encloses the embryo - provides warmth and protection
explain the term dichorionic
each twin has their own placenta/chorion
explain the term monochorionic
twins that share a placenta/chorion
explain the term diamniotic
each twin has their own amniotic sac
explain the term monoamniotic
twins share an amniotic sac
what can determine how independent the twins are of each other in the womb
the earlier the split of the amnion and chorion
e.g. the sooner after fertilisation the cells split, the more likely they are to develop separate amnions and chorions = better outcomes and more independence
what will most likely result from cleavage of the morula during days 1-3
cleavage of the morula = dichorionic/diamniotic twins
what will most likely result from cleavage of the blastocyst during days 4-8
cleavage of the blastocyst monochorionic/diamniotic twins
what will most likely result from cleavage of the implanted blastocyst during days 8-13
cleavage of the implanted blastocyst = monochorionic/monoamniotic
what will most likely result from cleavage of a formed embryonic disc during days 13-15
cleavage of formed embryonic disc = conjoined twins
when is DCDA most commonly seen
in dizygotic twins
when is MCDA most commonly seen
in monozygotic twins
when would DCDA be seen in monozygotic twins
if the split of the cells is very early i.e. before develops into a blastocyst
when is MCMA most commonly seen
rarest of the three combinations - but only seen in monozygotic twins
which of DCDA, MCDA and MCMA is most risky and why
MCMA - due to placental insufficiency and cord entanglement
what can increase mortality in monochorionic twin pregnancies
preterm labour congenital abnormalities growth restriction placental insufficiency twin-twin transfusion syndrome malpresentation 4x increased risk of death due to hypoxia for the second twin
when are DCDA twins most commonly delivered
37-38 weeks
when are MCDA twins most commonly delivered
36-37 weeks
when are MCMA twins most commonly delivered
32-34 weeks
what might determine if a mother has a c-section vs vaginal delivery with twins
complications
previous deliveries
presentation/lie of twins
what procedures/provisions are commonly needed to assist twin deliveries
theatre available CTG monitoring cord clamping scan 2nd twin for presentation stabalise lie/ECV oxytocin vaginal assisted/c-section available
