Multiple pregnancy

Question 1

Monozygotic/dizygotic
Monochorionic/dichorionic meaning
Monoamniotic/diamniotic

Answer 1

Monozygotic - identical twins (from one zygote)
Dizygotic - non identical - from two zygotes - two sperm fertilise two different eggs - always DCDA

Monochorionic - share a placenta, dichorionic - separate placentas

Monoamniotic - share an amniotic sac, diamniotic - two separate amniotic sacs

MZ twins can be:

• DCDA
• MCDA
• MCMA

Question 2

Signs of different types of twins on USS

Answer 2

DCDA - lambda sign and membrane separating the twins

MCDA - membrane separating the twins with a T sign

MCMA - no membrane separating the twins

Question 3

Risks to the mother - increased risk of …

Answer 3

Hyperemesis gravidarum
Anaemia
Polyhydramnios
Gestational hypertension
Pre-eclampsia
Gestational diabetes
VTE
Higher risk of intervention in labour and need for emergency C-section
PPH

Question 4

Risks to the foetus - increased risk of

Answer 4

Miscarriage/stillbirth
Growth restriction
Premature delivery - both iatrogenic and spontaneous
Congenital abnormalities

In monochorionic twins:

• TTTS
• Twin anaemia - polycythaemia sequence (TAPS)

(Cord entanglement in MCMA twins)

Question 5

What is TTTS

Answer 5

Twin-twin transfusion syndrome

When there is a connection between the blood supplies of the two fetuses, one fetus (the recipient) may receive the majority of the blood from the placenta, while the other fetus (the donor) is starved of blood.

Recipient twin - can become overloaded with fluid and develop heart failure, polyhydramnios

Donor twin - has growth restriction, anaemia, oligohydramnios

Question 6

Management of TTTS

Answer 6

Referral to specialist foetal medicine centre

Laser treatment to destroy the connection between the two blood supplies

Question 7

What is TAPS?

Answer 7

Similar to TTTS but one twin becomes anaemic whilst the other is polycythaemic (Raised Hb)

Question 8

Management of twin pregnancy antenatally

Answer 8

Increased scans - every 2 weeks from 16w for monochorionic twins, every 4 weeks from 20 weeks for dichorionic twins

Question 9

Delivery of twins

Answer 9

Uncomplicated - offer planned birth:

• 32-34 weeks for MCMA - via elective C-section
• 36-37 weeks for MCDA
• 37-38 weeks for DCDA

Give corticosteroids before delivery to mature the lungs

Type of delivery:

• Vaginal delivery is possible if first baby is cephalic
• C-section may still be needed for the second baby after successful delivery of the first baby - in 10-30% as twin 2 may suffer cord prolapse, fetal distress, malpresentation
• Elective C-section is advised when the presenting twin is not cephalic