obs - multiple pregnancy Flashcards
types of multiple pregnancy? aetiology? most common?
Most common = Dizygotic twins 66%
- Dizygotic twins : 2 oocytes. fraternal
- Monozygotic twins:
a. DCDA: dichorionic diamniotic- cleavage of morula (day 1-3)
b. MCDA: monochorionic diamniotic - 70%
- cleavage of the blastocyst (d 4-8)
c. MCMA: monochorionic monoamniotic
- cleavage of implanted blastocyst (d 8-13)
d. Conjoined
- cleavage of formed embryonic disk (13-15)
- or incomplete division
how is multiple pregnacy diagnosed?
Physical examination:
Vomiting more marked in early pregnancy
Uterus larger than expected for dates
Palpable before 12 weeks
complicatoins of multiple pregnancy?
Maternal:
All obstetric risks exaggerated:
- DM, pre eclampsia
Fetal: IUGR - superficial artery-artery anastomoses Preterm delivery Increased risk of handicap Breech delivery TTTS - in monochorionic ones
which twins are at risk of TTTS?
MCDA monochorionic diamniotic
how do twins present in TTTS? prognosis?
One twin = donor -> volume depleted, develops anaemia, IUGR and oligohydramnios
One twin = recipient -> volume overloaded, polycythaemia, cardiac failure, polyhydramnios
50% chance both will survive
how does co-twin death occur?
If one twin dies, the drop in BP allows acute transfusion of blood from the other -> hypovolaemia
15% chance of co-twin death. risk is higher if 1st death is before 24 weeks. if survive, high risk neurological damage.
why does 2nd twin have incresaed chance of dying?
due to hypoxia, cord prolapse, tetanic uterine contraction or placental abruption
which signs would you see on US depending on the type of twin pregnancy?
DC: dividing membrane is thicker as it meets the placentas = lambda sign
MC: thin and perpendicular to the placenta = T sign
when is TTTS usually diiagnosed?
Management?
16-22 weeks
- Refer to specialist foetal medicine centre
- If < 26 weeks – foetoscopic laser ablation of placental anastomoses - definitive in severe cases
- Or Expectant management - weekly ultrasound
- delivered between 34-37 weeks
others - see other card
what is the risk with MCMA: monochorionic monoamniotic twins?
cords always get entangled -> fetal death in utero
how are multiiple pregnancies managed?
how are breech deliveries conducted?
Lots of monitoring throughout pregnancy, looking out for complications
Obstetrciian led care.
Can deliver vaginally
- may end up in c-section if 2nd twin not coming
Elective section usually offered.
Inform that 60% of twin pregnancies result in spontaneous birth before 37 weeks!!
Sumary of monitoring:
▪ Monochorionic: 2-weekly growth and Doppler from 16 weeks
(refer to foetal medicine specialist)
▪ Dichorionic: 4-weekly growth and Doppler from 20 weeks
Maternal risks of multiple pregnancy?
1st trimester - increased pregnancy sx , anemia
2nd
3rd - PPH, Preterm labour
Fetal risks of multiple pregnancy?
1st. - congenital malformations , cerebral palsy
2nd - growth restriction, TTTS, TRAP
3rd trimester - preterm birth, cord entanglement (all monochorionic will have this).
What is risk of death in twin pregnancy?
Don’t forget in paces, woman may come to discuss her twin pregnancy. - so know risk factors for twins etc.
Perinatal mortality 37 in thousand - twins
52 in thousand - triplets
Which sign on the dating scan indicates dichorionic pregnancy? And monochorionic?
Lambda - dichroic
T sign - mono
TTTS can occur in dizygous twins, true or false?
False
Which twins have the highest risk of mortality?
MCMA - 30-70%
In twins what can Nuchal translucency scan tell you in multiple pregnancy?
Chromosome Anomaly
TTTS
Note; accuracy is less than for single pregnancy.
What does cervical length tell us?
If less than 25mm, this predicts delivery before 34 weeks
What is ANCare like for multiple pregnancy?
Specialist twin clinic. - obstetrician
Multiple births foundation
What is risk of malformations with twins?
2-3x higher than for Singleton
Midline malformations higher - haloprosencephaly etc
What are the different forms of placental anastomoses?
V-V
A-V
A-A?
When does TTTS become obvious to diagnose?
2nd trimester
Oligo and Polyhydramnios
what are the options for TTTS treatment?
Amnioreduction - controls Polyhydramnios
Septostomy - hole in amniotics sac to allow the amniotic fluid to move from one baby to the other. alternative to amnioreduction
Laser ablation
