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Obstetrics > RANZCOG - MCDA twin pregnancy > Flashcards

RANZCOG - MCDA twin pregnancy Flashcards

1
Q

What are the specific complications of MCDA twin pregnancy?

A

Twin to twin transfusion syndrome
selective fetal IUGR
death of one twin
twin reversed arterial perfusion (TRAP) sequence

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2
Q

when should chronicity be determined?

A

ideally on an USS before 14/40

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3
Q

What are the serial growth scan recommendations for an MCDA twin pregnancy?

A

fortnightly growth scan from 16/40 to assess for TTTS or selective fetal IUGR

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4
Q

What would you advise a woman with an MCDA twin pregnancy about the efficacy of aneuploidy screening?

A
  • lower detection rate in twin pregnancy

- NIPT therefore advised (higher risk of getting inadequate fetal fraction though)

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5
Q

What is twin to twin transfusion syndrome

A

unbalanced blood flow from one twin to the other
AV/VA discordance of large vessels
donor twin has bigger or more AV anastamoses
the net flow of blood is from the donor to the recipient

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6
Q

What is the staging criteria for TTTS called and how many stages are there?

A

Quintero staging for TTTS

5 stages

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7
Q

What is stage 1 of the Quintero staging system?

A
  • MVP in donor twin of <2cm, in recipient >8cm

MVP = max vertical pocket

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8
Q

What is stage II of the Quintero staging system for MCDA twin pregnancy?

A

absent bladder in donor twin

non visualisation of bladder in donor twin following 60 mins of monitoring

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9
Q

What is stage III of the Quintero staging system for TTTS?

A
  • absent or reversed umbilical artery diastolic flow
  • reversed DV a wave
  • pulsatile umbilical vein flow
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10
Q

What is stage IV of TTTS as per Quintero staging system?

A
  • hydrops in one or both twins
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11
Q

What is stage V or TTTS as per Quintero staging system?

A
  • fetal demise of one or both twins
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12
Q

what are the management options available for TTTS?

A
  • expectant or conservative management
  • intentional septostomy (non longer used really)
  • amnioreduction
  • laser photocoagulation
  • selective reduction
  • termination
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13
Q

What are the benefits of amnioreduction?

A
  • reduces intra-amniotic pressure
  • reduces intravascular pressure
  • improves placental blood flow
  • reduces the incidence of pre term labour (and the complications of polyhydramnios)
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14
Q

What are the complications/risks of amnioreduction?

A
  • risk of serial procedures being required
  • PPROM
  • infection
  • abruptions
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15
Q

What are the complications/risks of amnioreduction?

A
  • risk of serial procedures being required
  • PPROM
  • infection
  • abruptions
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16
Q

What are the average survival rates for fetus that have undergone amnioreduction?

A

50-65%

17
Q

Describe fetoscopic laser photocoagulation as a procedure

A
  • usually performed between 17 and 26 weeks gestation (afterward might as well deliver babies!)
  • USS guided placement of fetoscope
  • laser introduced through fetoscope
  • aim is to interrupt anastomoses causing TTTS
  • functionally divides the placenta into two regions - each supplying one of the twins
    ‘dichorionisation’ of the monochorionic placenta
18
Q

what are the survival rates following fetoscopic laser coagulation?

A
  • perinatal survival 75%
  • disease free survival 60%
  • fetal death 20%
  • severe neonatal morbidity 20%
  • neurological impairment 8%
  • neonatal mortality 3%
19
Q

Describe twin anaemia polycythaemia sequence TAPS

A
  • discordant fetal blood flow from one to the other
  • small anastomoses (<1mm) therefore the result is a subtle transfusion
  • donor twin - anaemia develops, recipient twin - polycythaemia
  • MCA PSV is used to assess for fetal anaemia
20
Q

How does the MCA PSV indicate anaemia?

A
  • increased velocity
  • the anaemia causes an increased cardiac output –> results in preferential shunting and reduced viscosities –> increased blood flow particularly cerebral blood flow
21
Q

what are the management options for TAPS sequence?

A
  • expectant, planned birth, laser photocoagulation, transfusion
22
Q

What does acute feto-fetal transfusion syndrome refer to?

A

A sudden drop in pressure and/or heart rate of one twin resulting in a large uni-directional blood flow from the co-twin
may lead to brain injury or death

23
Q

When does acute feto-fetal transfusion occur?

A

With the demise of one twin - transfusion from surviving to dead twin
- 20-30% risk of brain injury
- 15% risk of death
Transient bradycardia (i.e. with type III gratacos sFGR)

23
Q

When does acute feto-fetal transfusion occur?

A

With the demise of one twin - transfusion from surviving to dead twin
- 20-30% risk of brain injury
- 15% risk of death
Transient bradycardia (i.e. with type III gratacos sFGR)

24
Q

What is the incidence of sFGR in MCDA twin pregnancies and what is the definition?

A
  • 10% of MC pregnancies

- EFW <10% and or discordance of >20%

25
Q

What is the cause of sFGR?

A
  • discrepancy in the share of placental territory

- inter-twin anastomoses

26
Q

Describe the gratacos (USS) staging of sFGR in MCDA twin pregnancies

A

Umbilical artery doppler:
1 - normal doppler/raised but forward flow
2 - constant absent, or reversed EDF
3 - intermittent absent or reversed EDF (cycling)

27
Q

What are the placental findings associated with gratacos type 1 sFGR?

A

unequal sharing
big anastamoses which compensate for unequal territory share
No/small AA

28
Q

What are the placental findings associated with type II gratacos sFGR?

A
  • very unequal sharing
  • small anastamoses which can compensate but for shorter time than the big anastamoses in type 1
  • No/small AA
29
Q

What are the placental findings associated with Type III gratacos sFGR?

A
  • very unequal sharing

- large AA, compensate for unequal territory share and prolong pregnancy but high risk of acute transfusion

30
Q

What is the clinical course of MC pregnancies complicated by type I gratacos sFGR?

A
  • relatively benign
  • small weight discordance
  • usually deliver >34
31
Q

What is the clinical course of MCDA twin pregnancies complicated by gratacos type II sFGR?

A
  • high risk of deterioration and IUD of FGR twin
  • low risk of intrauterine brain injury of co-twin
  • mean GA of delivery 29/40W
32
Q

What is the clinical course of MCDA twin pregnancies complicated by gratacos type III sFGR?

A
  • low risk of hypoxia for FGR twin
  • can prolong pregnancy >32/40 but 10-15% risk of unexpected IUD of FGR twin and 10-15% risk of brain injury of co-twin (acute transfusion following demise)
33
Q

How do you manage sFGR complicated MCDA twin pregnancies?

A
  • growth fortnightly (routine)
  • Umbilical and MCA doppler at least weekly
  • If UAPI abnormal then include DV
  • timing of birth decided by fetal wellbeing, interval growth, BPP, DV, and or computerised CTG
34
Q

How do you manage MCDA type 1 gratacos pregnancy?

A
  • outpatient management
  • fortnightly growth USS
  • delivery by 34-36 weeks
35
Q

How do you manage type II and III gratacos MCDA twin pregnancy?

A
  • in-patient management
  • twice weekly doppler studies
  • twice daily CTG
  • corticosteroids
  • delivery by 32/40
36
Q

How do you manage a pregnancy complicated by IUD of co-twin?

A
  • MCA PSV doppler for anaemia
  • CTG
  • expectant management
  • offer MRI at 4-6 weeks
  • neurodevelopment follow up
37
Q

What does Twin reversed arterial perfusion sequence refer to?

A

MCDA twin pregnancy complicated by an acardiac twin, and a pump twin
The acardiac twin is perfused due to placental anastamoses from the pump twin
The acardiac twin - is poorly formed with either a poorly developed absent heart, upper body and head
The pump twin is at increased risk of high output cardiac failure/hydrops and IUD

38
Q

What is the treatment for TRAP sequence?

A

not always required but if is required then <16/40 in tertiary centre with cord occlusion or interstitial laser

Obstetrics (28 decks)

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