Management of monochorionic twin pregnancy GT51 and NICE 129 Multiple Pregnancy

Question 1

At what gestation should an USS be performed to determine chorionicity?

Answer 1

11+0 - 13+6

CRL 45-84mm

Question 2

What is the USS surveillance for MC twins following detailed anatomy scan?

Answer 2

Every 2 weeks from 16+0 until delivery

Question 3

Which parameters should be measured on USS for MC twins?

Answer 3

Deepest vertical pocket (LV)
Umbilical dopplers
Visualise fetal bladders
EFW

Question 4

What does TAPS stand for?

In how many cases does it occur post-laser treatment

Answer 4

Twin anaemia-polycythaemia sequence - discordant Hb levels with NO significant oligo/polyhydramnios. ‘Slow’ transfusion

Screened for using MCA dopplers following e.g. laser treatment for TTTS or other complicated MC twins e.g. selective growth restriction

In 13% cases post laser ablation; 2% spontaneously

Question 5

What % EFW discordance is associated with increased perinatal risk in MC twins?

In how many MC pregnancies does it occur (with/without TTTS)?

Answer 5

20%

Without TTTS - 15%
With TTTS - >50%

Question 6

How is TTTS staged?

Answer 6

Quintero staging I - V

Laser > Stage 2 or more

Question 7

What is the recommended treatment of TTTS presenting <26/40?

Answer 7

Fetoscopic laser ablation (Solomon technique) > amnioreduction or septostomy

Question 8

What is the surveillance of MC twins following treatment for TTTS?

Answer 8

Weekly detailed USS (brain, heart, limbs) and serial umb Dopplers, MCA PSV, DV Dopplers.
2/52 after treatment back to 2/52 surveillance if all well

Question 9

By when should MC twins previously complicated by TTTS be delivered?

Answer 9

34+0 - 36+6

Question 10

What is the % of death and neurological abnormality in the surviving co-twin following death of an MC twin?

Answer 10

Death - 15%

Neuro - 26%

Question 11

How should neuro morbidity be determined following the death of a MC co-twin?

Answer 11

Fetal MRI 4/52 after demise (if adds value to management)

Question 12

When should otherwise uncomplicated MC twins be offered delivery?

Answer 12

From 36+0/40 after steroids unless earlier indication

Vaginal if diamniotic, unless other indications

Question 13

By when should MCMA twins be delivered?

Answer 13

32+0 and 34+0 weeks by Caesarean Section

Question 14

What % of twin pregnancies in the UK are MC?

And what proportion of these are MCMA?

Answer 14

30%

MCMA 1% of these

Question 15

At which stage embryo transfer is monozygosity highest?

Answer 15

5 day blastocyst > 3/7 cleavage stage

Question 16

What are the complications of inter-twin vascular anastomoses?

Answer 16

• TTTS
• Sel. growth restriction
• TAPS (twin anaemia-polycythaemia sequence) 2% uncomplicated MC; 13% post laser ablation
• TRAP sequence (twin reversed arterial perfusion) 1% MC pregnancies
• Single IUD

Question 17

In what % of cases do MC twin placentas have bidirectional vascular anastomoses

Answer 17

80%

Question 18

What % of MC pregnancies are complicated by TTTS?

Answer 18

15%

Question 19

What is TRAP sequence?

Answer 19

twin reversed arterial perfusion

‘Acardiac’ twin being perfused by ‘normal’ pump twin

Question 20

How is sGR staged in MC twin pregnancies?

Answer 20

I - Growth discordance, both + EDV
II - Growth discordance, AREDV in one or both fetuses
III - Growth discordance, cyclical umbilical artery diastolic waveforms (ie intermittent AREDV)

Question 21

What % of MC placentas are bilobed?

Answer 21

3%

Question 22

How is TTTS diagnosed ultrasonigraphically?

Answer 22

• Significant AF discordance (2/8cm; 10 if >20/40)
• Discordant bladder appearances
• Haemodynamic and cardiac compromise in both twins

Question 23

What is the prevalence of conjoined twins and what is the survival rate?

Answer 23

1 in 90,000-100,000 pregnancies

Survival - 25%, majority with significant morbidity

Question 24

What is the multiple pregnancy rate and what % of total live births does it constitute?

Answer 24

16/1000 in 2009
3% total live births

Makes up 24% of successful IVF treatments

Question 25

What is the increase in perinatal mortality with a multiple pregnancy?

Answer 25

x2.5

Question 26

What is the stillbirth rate for multiple pregnancy?

Answer 26

Twins 12.3/1000
Triplets 31.1/1000
20% secondary to TTTF

B/G 5/1000 singleton

Question 27

What is the preterm birth rate for multiple pregnancy?

Answer 27

50%

10% will be <32/40

Question 28

How much more common are major congenital abnormalities with multiple pregnancy?

Answer 28

4.9% more common

Question 29

What % of unexplained stillbirth with multiple pregnancies are associated with BW<10th centile?

Answer 29

66%

39% singletons

Question 30

When should MCDA twins be delivered?

Answer 30

From 36/40

Question 31

When should DCDA twins be delivered?

Answer 31

37/40

Question 32

When should triplets be delivered

Answer 32

35/40