T2 L15 Multiple Pregnancies Flashcards
What is the incidence of twin births (per 1000 deliveries) in the following regions:
1) Far East
2) Europe
3) Nigeria
1) Far East = 2-7
2) Europe = 9-20
3) Nigeria = 20-45
Why was there a big increased in multiple births between 1986 and 1998?
More embryos were being put back in IVF treatment.
What factors contribute to increased likelihood of a multiple pregnancy? (aetiology)
- Ethnicity
- Increasing maternal age
- Increasing parity
- Family history
- Fertility treatment
NOTE: All these are factors for ‘super ovulation’
What is a monozygous twin pregnancy?
1 fertilised egg further divides to form identical embryos
What fraction of twin pregnancies are monozygous?
1/3
What is a dizygous twin pregnancy?
2 eggs fertilised by 2 sperms to form non-identical embryos
What fraction of twin pregnancies are dizygous?
2/3
Why type of pregnancy are dizygous twins?
Diaminotic
Dichorionic / two placentae
a.k.a DCDA
Why type of pregnancy are monozygous twins if splitting occurs at the two cell stage?
Dichorionic / two placentae
Diamniotic
a.k.a DCDA
Why type of pregnancy are monozygous twins if splitting occurs at the early blastocyst level (with 2 inner cell mass)?
Monochorionic / “joined” or same placentae
Diamniotic
a.k.a MCDA
How many days after fertilisation does the blastocyst form?
4 days
Why type of pregnancy are monozygous twins if splitting occurs when there is one inner cell mass?
Monochorionic / “joined” or same placentae
Monoamniotic
a.k.a MCMA
How are twin pregnancies diagnosed?
Uterine size
Up to 50% at delivery worldwide
Ultrasound
What is the lambda plate / sign?
The area where the two chorions meet. It strongly suggests a dichorionic twin pregnancy
COMPLETE THE SENTENCE
All ______ are dichorionic
Dizygous twins
COMPLETE THE SENTENCE
All dichorionic twins are __________
Diamniotic
Describe the circulation in dichorionic pregnancies?
The circulation is separate, due to separate placantae and chorions
What ratio of monozygous twins are dichorionic?
1 : 3
Describe monochorionic pregnancies
Monozygous twins may be monochorionic (2/3) or dichorionic
MC have vascularly joined placentae
MC twins have 3x increased loss rate
MC twins usually diamniotic, but the membrane dividing the twins is usually very thin
What are the complications of a multiple pregnancy?
“Everything except post-dates”
- Symptoms of pregnancy
- Anaemia
- Hypertension
- Intrauterine growth restriction
- Pre-term labour
- Delivery problems
- Perinatal mortality
What are the different mortality types in twin pregnancies?
Stillbirth (SB) – after 24 weeks (dies utero)
Early neonatal – first 7 days
Neonatal – in first 28 days
Perinatal – SB + early neonatal
Infant – first year
Rates are per 1000 births
Compare the risk of different mortality types in a singleton pregnancy with a twin pregnancy
Mortality rates for all types increases in a twin pregnancy compared with a singleton pregnancy
Compare the risk of different mortality types in a twin pregnancy with a triplet pregnancy
Mortality rates for all types increases in a triplet pregnancy compared with a twin pregnancy
Describe the 1st trimester management in twin pregnancies
Discuss screening for chromosomal anomalies
Determine chorionicity
Discuss fetal reduction if triplets or more
Describe the 2nd trimester management in twin pregnancies
Detection of fetal abnormality
Serial scans for growth for all
-DC monthly from 24 weeks
Serial scans for TTTS if MC twins
-2 weekly 16-28 weeks then monthly
Maternal complications
What risks are increased in monochorionic twins?
More fetal malformation
More fetal growth restriction
Twin to twin transfusion
What is unidirectional A-V shunt in twin to twin transfusion?
Blood is shunted from the umbilical artery to the umbilical vein
What is result of unidirectional A-V shunt in twin to twin transfusion?
Unbalanced placental vascular anastamoses
The baby that is getting too little blood (donor) fails to thrive and is smaller
The baby that gets too much (the recipient) can go into cardiac failure and has a higher mortality rate
How is a unidirectional A-V shunt treated)
Laser treatment or amnio-reduction
Early delivery by caesarean
Describe the 3rd trimester management in twin pregnancies
Scanning as in 2nd trimester
Monitor blood pressure (of mother)
Pre-term labour
Delivery planning
At what week of gestation are dichorionic twins delivered? What method of delivery is used?
37-38 weeks
Vaginal or caesarean
NOTE: If the first baby is not head down, then a caesarean section is carried out. The mode of delivery is dependent on the first baby.
At what week of gestation are monochorionic twins delivered? What method of delivery is used?
36-37 weeks
Caesarean
Describe the labour management in twin pregnancies
Monitoring both twins
Problems delivering twin II (twin II often does slightly worse than twin I and are often at more risk)
Risk of postpartum bleed
NOTE: Twin I and twin II are determined by the position of their placenta in the womb
What is puerperium?
The period of about six weeks after childbirth during which the mother’s reproductive organs return to their original non-pregnant condition.
What problems are encountered during puerperium by the mother? How can she be supported?
Feeding difficulties
Emotional & social support
Describe the factors of high order multiple pregnancies (i.e. three or more foetuses)?
DURING PREGNANCY
- Determine chorionicity
- Consider fetal reduction
DURING AND AFTER DELIVERY
- High risk of preterm labour
- Deliver preterm by caesarean
- Postpartum haemorrhage
- Difficult puerperium & after
