Multiple Pregnancy

Question 1

What are the 2 types of twin pregnancy?

Answer 1

Monozygotic 1/3
Dizygotic 2/3

Question 2

What do monozygotic twin pregnancies arise from?

Answer 2

division of the fertilized oocyte into 2 embryonic layers

Question 3

What do dizygotic twin pregnancies arise from?

Answer 3

fertilization of 2 oocytes with 2 spermatozoa

Question 4

What are 4 predisposing factors for dizygotic twins?

Answer 4

Previous multiple pregnancy
Maternal FH
Increasing maternal age >35y
Induced ovulation + IVF

Question 5

What is the only chorionic cavity and amniotic sac composition for dizygotic pregnancies?

Answer 5

Dichorionic-Diamniotic

separate placentas + separate amniotic sacs

Question 6

What are the 4 possible compositions of placenta and amniotic sacs for monozygotic pregnancies?

Answer 6

Monochorionic-Diamniotic 70%

Dichorionic-Diamniotic 20-30%

Monochorionic- Monoamniotic 1-5%

Monochorionic-Monoamniotic (conjoined twins) <0.1%

Question 7

What are Dichorionic-Diamniotic pregnancies? When does the zygote divide?

Answer 7

2 placenta
2 amniotic sacs

Division within first 3 days after conception

Question 8

What are Monochorionic-Diamniotic pregnancies? When does the zygote divide?

Answer 8

1 placenta
2 amniotic sacs

Division day 4-7 after conception

Question 9

What are Monochorionic-Monoamniotic pregnancies? When does the zygote divide?

Answer 9

Share 1 placenta + 1 amniotic sac

Division day 8-11 after conception

Question 10

What are Monochorionic-Monoamniotic (conjoined) pregnancies? When does the zygote divide?

Answer 10

Share 1 placenta + 1 amniotic sac + are conjoined

Division day 12+ after conception

Question 11

What is found on examination in multiple pregnancies?

Answer 11

Fundal height + abdominal girth are unusually large for the gestational age.

> ,2 fetal HRs can be heard on auscultation
.

Question 12

What is seen on ultrasound in dichorionic twins?

Answer 12

LAMBDA sign
Chorionic cavities separated

Question 13

What is seen on ultrasound in monochorionic diamniotic twins?

Answer 13

T-sign
1 chorionic cavity + each twin has individual amniotic sac

Question 14

What is the most common complication of multiple pregnancy?

Answer 14

Preterm labour

Question 15

Give 5 antenatal complications of multiple pregnancy

Answer 15

Hyperemesis gravidarum
GDM
Preeclampsia, eclampsia + pregnancy induced HTN
Miscarriage/ loss of 1 fetus
Antepartum haemorrhage

Question 16

Give 4 intrapartum complications of multiple pregnancy

Answer 16

Prolonged 1st stage of labour
Premature placenta abruption after 1st born
Cord prolapse
PPH

Question 17

What is twin-to-twin transfusion syndrome?

Answer 17

Blood is continuously shunted from one twin to the other through vascular anastomoses on the shared placenta, posing a risk to both fetuses.

Affects 10-15% monochorionic pregnancies

Question 18

Give 3 complications of twin-to-twin transfusion syndrome for the recipient twin

Answer 18

Polycythemia

Hypervolemia: More blood –> more cardiac strain –> hydrops fetalis

Polyhydramnios in diamniotic pregnancies

Question 19

Give 4 complications of twin-to-twin transfusion syndrome for the donor twin

Answer 19

Anemia

Growth retardation

Hypovolemia, dehydration (stuck twin or cocooned appearance)

Oligohydramnios in diamniotic pregnancies

Question 20

Give 3 symptoms of TTTS

Answer 20

Sudden weight gain
Abdo pain
SOB

Question 21

What is diagnostic of TTTS?

Question 22

What is the management of TTTS?

Answer 22

If <26w: foetoscopic laser ablation of vascular anastomoses

If >26w: delivery

Question 23

Give 4 fetal complications in multiple pregnancy

Answer 23

Spontaneous reduction or vanishing twin syndrome

Twin to Twin transfusion syndrome

Cord entanglement (only in monoamniotic)

Increased mortality + morbidity: IUGR, prematurity, congenital abnormalities

Question 24

How is gestational age calculated in multiple pregnancies?

Answer 24

Use largest baby to estimate GA at dating scan

Question 25

Describe the antenatal care in multiple pregnancies

Answer 25

Obstetric led
Increase screening for anaemia: additional FBC at 20w
Serial growth + doppler USS: monitor for IUGR + TTTS: 2-4 weekly depending on chorionicity + amnionicity
Consider need to refer to tertiary level foetal medicine centre

Question 26

Give 8 indications for referral to a tertiary level foetal medicine centre

Answer 26

Pregnancy with shared amnion
Discordant foetal growth (>25% difference)
Foetal anomaly (structural or chromosomal)
Discordant foetal death
TTTS
Twin anaemia polycythaemia sequence
Twin reverse arterial perfusion sequence
Conjoined twins/ triplets

Question 27

What delivery is possible in multiple pregnancies?

Answer 27

Dichorionic-Diamniotic + Monochorionic-Diamniotic: vaginal delivery if 1st twin is cephalic

Monochorionic-Monoamniotic + Triplets: elective C section

Question 28

What is the recommended type of elective birth in dichorionic-diamniotic twins?

Answer 28

37w

Question 29

What is the recommended type of elective birth in monochorionic-diamniotic twins?

Answer 29

36w (after a course of steroids)

Question 30

What is the recommended type of elective birth in monochorionic-monoamniotic twins?

Answer 30

32w (after a course of steroids)

Question 31

What is the risk of preterm birth in twin pregnancies?

Answer 31

60%