RANZCOG - MCDA twin pregnancy Flashcards
(39 cards)
What are the specific complications of MCDA twin pregnancy?
Twin to twin transfusion syndrome
selective fetal IUGR
death of one twin
twin reversed arterial perfusion (TRAP) sequence
when should chronicity be determined?
ideally on an USS before 14/40
What are the serial growth scan recommendations for an MCDA twin pregnancy?
fortnightly growth scan from 16/40 to assess for TTTS or selective fetal IUGR
What would you advise a woman with an MCDA twin pregnancy about the efficacy of aneuploidy screening?
- lower detection rate in twin pregnancy
- NIPT therefore advised (higher risk of getting inadequate fetal fraction though)
What is twin to twin transfusion syndrome
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
What is the staging criteria for TTTS called and how many stages are there?
Quintero staging for TTTS
5 stages
What is stage 1 of the Quintero staging system?
- MVP in donor twin of <2cm, in recipient >8cm
MVP = max vertical pocket
What is stage II of the Quintero staging system for MCDA twin pregnancy?
absent bladder in donor twin
non visualisation of bladder in donor twin following 60 mins of monitoring
What is stage III of the Quintero staging system for TTTS?
- absent or reversed umbilical artery diastolic flow
- reversed DV a wave
- pulsatile umbilical vein flow
What is stage IV of TTTS as per Quintero staging system?
- hydrops in one or both twins
What is stage V or TTTS as per Quintero staging system?
- fetal demise of one or both twins
what are the management options available for TTTS?
- expectant or conservative management
- intentional septostomy (non longer used really)
- amnioreduction
- laser photocoagulation
- selective reduction
- termination
What are the benefits of amnioreduction?
- reduces intra-amniotic pressure
- reduces intravascular pressure
- improves placental blood flow
- reduces the incidence of pre term labour (and the complications of polyhydramnios)
What are the complications/risks of amnioreduction?
- risk of serial procedures being required
- PPROM
- infection
- abruptions
What are the complications/risks of amnioreduction?
- risk of serial procedures being required
- PPROM
- infection
- abruptions
What are the average survival rates for fetus that have undergone amnioreduction?
50-65%
Describe fetoscopic laser photocoagulation as a procedure
- 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
what are the survival rates following fetoscopic laser coagulation?
- perinatal survival 75%
- disease free survival 60%
- fetal death 20%
- severe neonatal morbidity 20%
- neurological impairment 8%
- neonatal mortality 3%
Describe twin anaemia polycythaemia sequence TAPS
- 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
How does the MCA PSV indicate anaemia?
- increased velocity
- the anaemia causes an increased cardiac output –> results in preferential shunting and reduced viscosities –> increased blood flow particularly cerebral blood flow
what are the management options for TAPS sequence?
- expectant, planned birth, laser photocoagulation, transfusion
What does acute feto-fetal transfusion syndrome refer to?
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
When does acute feto-fetal transfusion occur?
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)
When does acute feto-fetal transfusion occur?
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)
