Multiples Flashcards
What is the epidemiology of multiples?
•Twins: 1: 80 pregnancies (increasing). (1.8% all births in Ireland)
•Triplets: 1: 1000 (decreasing)
•ethnicity
DZ twin prevalence
Japan / Taiwan = 2-7 / 1000 births
Europe / Australia / USA = 8-20 / 1000 births
Nigeria / Zimbabwe / Jamaica = > 20 / 1000 br
What is the etiology of dizygotic twins?
- genetics
- increased maternal age
- high parity
- high BMI
- taller maternal height
The incidence of multiple pregnancy is increased in (T/F)
•People of afro-carribean race
•In women treated with bromocriptine for infertility
•In women treated by IVF
•With advancing maternal age
•First pregnancies
•People of afro-carribean race (T)
•In women treated with bromocriptine for infertility (F)
•In women treated by IVF (T)
•With advancing maternal age (T)
•First pregnancies (F)
.
Monozygotic Dizygotic (70%)
uniovular binovular
‘identical’ ‘fraternal
What determines whether they share the same amnion or chorion?
When zygote splits
Which of the following is true in relation to twin pregnancies
•Dizygotic twins are always the same sex
•In monzygotic twins when the zygote splits between day 4-8 the pregnancy will be dichorionic, monoamniotic
•70% of twin pregnancies are monozyotic
•In monozygotic pregnancies when the zygote splits after day 13 conjoined twins will develop
•Binovular twins are also called identical twins
When is the mono or dichorionic ultrasound diagnosis best done?
first trimester (Twins of opposite gender always DC). Keep photograph in the notes.
What can help determine if the twins are mono or dichorionic?
A) Number of placental masses
If one placental mass
B) -The ‘T’ sign predicts monochorionicity
-The ‘λ’ sing predicts dichorionicity.
What are the features of the intertwin membrane in a di-chorionic di-amniotic (DCDA) pregnancy?
•composed of two chorionic and two amniotic layers
•usually has a thick (often taken as > 2 mm ) inter-twin membrane
•may demonstrate a twin-peak sign at its margin
What are the features of the intertwin membrane in a mono-chorionic mono-amniotic (MCDA) pregnancy?
•composed two amniotic layers only
•usually has a thin (often taken as < 2 mm) inter-twin membrane
What is the T sign?
Thin membrane-just amnions between them
Makes a T-shape where membranes meet placenta (perpendicular to shared placenta)
What is the λ sign?
Membrane between them easy to see (4 layers thick). If two placentas close together then there is a triangular shape where the membranes meet the placenta
How are twins picked up as a clinical diagnosis?
Symptom?
•Marked vomiting in early pregnancy
Abdominal Examination?
•Uterus large for dates (palpable <12weeks)
•3 or more foetal poles
•2 foetal heart beats
•Normally picked up on ultrasound
What are the maternal ante partum complications of twin pregnancies?
•Hyperemesis
•Gestational Diabetes (? Increased hormones)
•Pre-eclampsia
•APH (PP: large placenta PA: ? Related to PET risk)
PPH (stretch effect and decreased tone)
•Anaemia (dilutional and low folate and iron)
•Mortality 2.5 times higher for twin pregnancy than singleton
What are the foetal ante partum complications for multiples?
•Increased mortality: 6 fold twins
•Increased morbidity: CP 4-5 fold twins, 18 fold trips
•IUGR: 14-25% of twin pregnancies
•Preterm-labour: 40% twins, 80% triplets
before 36 weeks.
•Miscarriage – (‘vanishing twin’ or foetus papyraceus in first trimester)
What is the median length of gestation for multiple pregnancies?
What is a foetus papyraceus?
Early miscarriage
Which of the following is not a known complication of twin pregnancies
•Pre-term delivery
•IUGR
•Maternal polycythaemia
•Hyperemesis
•Gestational Diabetes
What causes monochorionic complications in multiples?
•Many due to vascular anastomoses in shared placenta
•A-A: V:V bidirectional: superficial
•A-V: unidirectional: deep
What are monochorionicity complications largely due to?
Placental anastomoses
What are potential monochorioicity complications?
•IUGR: sIUGR 10-15% of MC twins (? Superficial art-art anastomoses ? Placental territory issue). Can lead to iAREDF in smaller twin.
•TAPS: twin anaemia-polycythaemia sequence
•Co-twin death: if one dies. Drop in BP means acute transfusion of blood from the other. Causes hypovolaemia and possible death or neuro damage.
What is TTTS?
Unequal blood distributions through anastomoses (A-V) in shared placenta
How do twins with TTTS present?
What staging system is used for TTTS?
Quintero Staging system
•Stage I: Discrepancy of AF volume but foetal bladder of the donor twin remains visible sonographically.
•Stage II: The bladder of the donor twin is collapsed and not visible by ultrasound.
•Stage III: Critically abnormal foetal Doppler studies in either twin. This may include absent or reversed end-diastolic velocity in the umbilical artery, absent or reverse flow in the ductus venosus, or pulsatile flow in the umbilical vein.
