Multiple Gestation

Question 1

What is multiple gestation?

Answer 1

Multiple gestation = pregnancy of more than 1 foetus

Question 2

What is amnioncity?

Answer 2

Amnionicity = number of amnions (inner membranes) that surrounds foetus in a multiple pregnancy:

• Pregnancies with 1 amnion (all babies share amniotic sac) are monoamniotic
• Pregnancies with 2 amnions are diamniotic

Question 3

What is chorionicity?

Answer 3

Chorionicity = number of chorionic (outer) membranes that surrounds foetus in a multiple pregnancy:

• If there is 1 membrane, monochorionic
• If there are 2 membranes, dichorionic

Question 4

What are the different types of twin pregnancies?

Answer 4

Question 5

What does DCDA stand for?

Answer 5

Dichorionic diamniotic twins

Question 6

What does MCDA stand for?

Answer 6

Monochorionic diamiotic twins

Question 7

What does MCMA stand for?

Answer 7

Monochorionic monoamniotic twins

Question 8

What is the aetiology of multiple gestation?

Answer 8

• More than 1 egg released during 1 menstrual cycle
• If zygote divides after fertilisation
  
  • Identical twins
• IVF treatments
  
  • Often transfer more than 1 embryo to the uterus

Question 9

How is determiniation of zygosity and chorionicity done?

Answer 9

• Determination of zygosity and chorionicity is done by foetal USS
  
  • Lambda sign shows 2 placentas – diagnosing dichorionic diamniotic twins
  • T sign shows single placenta – diagnosing monochorionic diamniotic twins

Question 10

Is a USS, what sign diagnosis dichorionic diamniotic twins and what sign diagnosis monochorionic diamniotic twins?

Answer 10

Lambda sign - dichorinic diamniotic twins (2 placentas)

T sign - monochorionic diamniotic twins (1 placenta)

Question 11

What are possible complications of multiple gestation?

Answer 11

• Maternal
  
  • Preterm labour
  • Hyperemesis
  • Anaemia in pregnancy
  • Hypertension
  • Gestational diabetes
  • Postpartum haemorrhage
• Foetal
  
  • Growth restriction
  • Prematurity
  • Increased birth complications
  • Increased perinatal mortality/morbidity
  • In monochorionic twins, higher chance of
    
    • Twin-twin transfusion syndrome – blood moves from one foetus to other due to shared placenta, causing one baby to lose blood
    • Selective growth restriction
    • Twin anaemia polycythaemia sequence
    • Twin reversed arterial perfusion (TRAP)
    • Single twin death

Question 12

Describe the management of multiple gestation?

Answer 12

• Routine care including trisomy 21 screening and structural scans
• Specialist clinic with regular scans to monitor growth and identify complications
  
  • Dichorionic diamniotic required at least 8 antenatal visits
  • Monochorionic required at least 11 antenatal visits
• Monitor BP/commence oral iron if required
• Aim for delivery at
  
  • Dichorionic diamniotic (DCDA) – 37 weeks
  • Monochorionic diamniotic (MDCA) – 36 weeks
  • Triplets – 35 weeks
  • Aim for earlier delivery if maternal or foetal complications
  • All delivery vaginal, unless first twin isn’t cephalic position and if triplets offer caesarean section

Question 13

How many antenatal visits are required for dichorionic diamniotic twins, and how many for monochorionic diamniotic twins?

Answer 13

• Dichorionic diamniotic required at least 8 antenatal visits
• Monochorionic required at least 11 antenatal visits

Question 14

At what weeks should deliver be aimed for: dichorionic diamniotic twins, monochorionic diamniotic twins and triplets?

Answer 14

• Dichorionic diamniotic (DCDA) – 37 weeks
• Monochorionic diamniotic (MDCA) – 36 weeks
• Triplets – 35 weeks
• Aim for earlier delivery if maternal or foetal complications
• All delivery vaginal, unless first twin isn’t cephalic position and if triplets offer caesarean section