T2 L15 Multiple Pregnancies

Question 1

What is the incidence of twin births (per 1000 deliveries) in the following regions:

1) Far East
2) Europe
3) Nigeria

Answer 1

1) Far East = 2-7
2) Europe = 9-20
3) Nigeria = 20-45

Question 2

Why was there a big increased in multiple births between 1986 and 1998?

Answer 2

More embryos were being put back in IVF treatment.

Question 3

What factors contribute to increased likelihood of a multiple pregnancy? (aetiology)

Answer 3

• Ethnicity
• Increasing maternal age
• Increasing parity
• Family history
• Fertility treatment

NOTE: All these are factors for ‘super ovulation’

Question 4

What is a monozygous twin pregnancy?

Answer 4

1 fertilised egg further divides to form identical embryos

Question 5

What fraction of twin pregnancies are monozygous?

Answer 5

1/3

Question 6

What is a dizygous twin pregnancy?

Answer 6

2 eggs fertilised by 2 sperms to form non-identical embryos

Question 7

What fraction of twin pregnancies are dizygous?

Answer 7

2/3

Question 8

Why type of pregnancy are dizygous twins?

Answer 8

Diaminotic

Dichorionic / two placentae

a.k.a DCDA

Question 9

Why type of pregnancy are monozygous twins if splitting occurs at the two cell stage?

Answer 9

Dichorionic / two placentae

Diamniotic

a.k.a DCDA

Question 10

Why type of pregnancy are monozygous twins if splitting occurs at the early blastocyst level (with 2 inner cell mass)?

Answer 10

Monochorionic / “joined” or same placentae

Diamniotic

a.k.a MCDA

Question 11

How many days after fertilisation does the blastocyst form?

Answer 11

4 days

Question 12

Why type of pregnancy are monozygous twins if splitting occurs when there is one inner cell mass?

Answer 12

Monochorionic / “joined” or same placentae

Monoamniotic

a.k.a MCMA

Question 13

How are twin pregnancies diagnosed?

Answer 13

Uterine size

Up to 50% at delivery worldwide

Ultrasound

Question 14

What is the lambda plate / sign?

Answer 14

The area where the two chorions meet. It strongly suggests a dichorionic twin pregnancy

Question 15

COMPLETE THE SENTENCE

All ______ are dichorionic

Answer 15

Dizygous twins

Question 16

COMPLETE THE SENTENCE

All dichorionic twins are __________

Answer 16

Diamniotic

Question 17

Describe the circulation in dichorionic pregnancies?

Answer 17

The circulation is separate, due to separate placantae and chorions

Question 18

What ratio of monozygous twins are dichorionic?

Answer 18

1 : 3

Question 19

Describe monochorionic pregnancies

Answer 19

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

Question 20

What are the complications of a multiple pregnancy?

Answer 20

“Everything except post-dates”

• Symptoms of pregnancy
• Anaemia
• Hypertension
• Intrauterine growth restriction
• Pre-term labour
• Delivery problems
• Perinatal mortality

Question 21

What are the different mortality types in twin pregnancies?

Answer 21

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

Question 22

Compare the risk of different mortality types in a singleton pregnancy with a twin pregnancy

Answer 22

Mortality rates for all types increases in a twin pregnancy compared with a singleton pregnancy

Question 23

Compare the risk of different mortality types in a twin pregnancy with a triplet pregnancy

Answer 23

Mortality rates for all types increases in a triplet pregnancy compared with a twin pregnancy

Question 24

Describe the 1st trimester management in twin pregnancies

Answer 24

Discuss screening for chromosomal anomalies

Determine chorionicity

Discuss fetal reduction if triplets or more

Question 25

Describe the 2nd trimester management in twin pregnancies

Answer 25

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

Question 26

What risks are increased in monochorionic twins?

Answer 26

More fetal malformation More fetal growth restriction Twin to twin transfusion

Question 27

What is unidirectional A-V shunt in twin to twin transfusion?

Answer 27

Blood is shunted from the umbilical artery to the umbilical vein

Question 28

What is result of unidirectional A-V shunt in twin to twin transfusion?

Answer 28

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

Question 29

How is a unidirectional A-V shunt treated)

Answer 29

Laser treatment or amnio-reduction Early delivery by caesarean

Question 30

Describe the 3rd trimester management in twin pregnancies

Answer 30

Scanning as in 2nd trimester Monitor blood pressure (of mother) Pre-term labour Delivery planning

Question 31

At what week of gestation are dichorionic twins delivered? What method of delivery is used?

Answer 31

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.

Question 32

At what week of gestation are monochorionic twins delivered? What method of delivery is used?

Answer 32

36-37 weeks Caesarean

Question 33

Describe the labour management in twin pregnancies

Answer 33

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

Question 34

What is puerperium?

Answer 34

The period of about six weeks after childbirth during which the mother's reproductive organs return to their original non-pregnant condition.

Question 35

What problems are encountered during puerperium by the mother? How can she be supported?

Answer 35

Feeding difficulties Emotional & social support

Question 36

Describe the factors of high order multiple pregnancies (i.e. three or more foetuses)?

Answer 36

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