Multiple pregnancy Flashcards
What is meant by monozygotic?
1 sperm, 1 ovum
(early splitting of single fertilised ovum to form 2 genetically identical foetuses)
What is meant by dizygotic?
2 sperm, 2 ova
In order of earliest split to latest split - list the types of monozygotic twins
egg splits early
dichorionic diamniotic
monochorionic diamniotic
monochorionic monoamniotic
egg splits late
(even later = conjoined twins)
When does the zygote split in DCDA twins?
morula
When does the zygote split in MCDA twins?
at hatching
When does the zygote split in MCMA twins?
blastocyst splits up to 1 week after implantation
What is the most common type of monozygotic twins?
monochorionic diamniotic
When is chorionicity of twins determined?
USS at 11-14 weeks
What suggests dichorionic twins on USS?
thicker dividing line - lambda sign
What suggests monochorionic diamniotic twins on USS?
thinner dividing line
1 shared placenta
True or false: monochorionic diamniotic twins will always be identical
true
True or false: DCDA twins will always be identical
false
True or false: DCDA twins may be identical
true
Why is hyperemesis worse in multiple pregnancies?
drive by hCG
more foetuses = more hCG
What VTE prophylaxis is used if needed in pregnancy?
heparin
What is used for pre-eclampsia prophylaxis if needed in pregnancy?
aspirin
When is caesarean section recommended in twin pregnancy?
if twin 1 is not cephalic
What type of twins are at risk of twin to twin transfusion syndrome?
monochorionic diamniotic (MCDA)
What is twin to twin transfusion syndrome?
vascular anastomosis in placenta enabling unequal sharing between foetal circulations
discordant fluid –> heart failure –> death
What is an early sign of twin to twin transfusion syndrome on USS?
difference between fluid in each sac
(one polyhydramnios, one oligohydramnios)
When are MCDA twins scanned to monitor for twin to twin transfusion syndrome?
2 weekly from 16 weeks
uncommon to develop after 24-26 weeks but scans continue to monitor growth
How is twin to twin transfusion syndrome treated?
laser ablation of communicating vessels
When are different types of twins delivered?
MCMA = 32-33 weeks
MCDA = 36 weeks
DCDA = 37 weeks
How should twins be delivered?
can attempt NVD if 1st twin cephalic
if not, caesarean section
