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MCDA 
Supervisor: Dr Rafaie 
Presenter: Tan Lee Na 
19th September 2014
Are twins good?
Introduction 
 Both babies share one placenta 
 1/3 of twins in the UK have MC 
placentas 
 Recent increase in multiple...
Diagnosis: first trimester 
Chorionicity and amnionicity: best accuracy in 
1st trimester
MCDA
Diagnosis: 
second trimester 
A photographic record should be 
retained
MCDA 
Bidirectional arterio-arterial anastomosis
If unable to determine chorionicity, 
treat as monochorionic until 
proven otherwise
Dating 
 Use the largest baby to estimate gest 
age to avoid risk of estimating it from a 
baby with early growth patholo...
Management: first trimester 
 First trimester screening for 
aneuploidy 
 Anatomical survey 
 ?prediction of MCDA compl...
First trimester aneuploidy 
screening: 
 Offer information: 
- greater likelihood of T21 in multiple 
pregnancies 
- diff...
Aneuploidy screening 
 1st trimester screen: combined test (NT + 
bHCG + PAPP-A) 
 Calculate the risk per pregnancy for ...
Subsequent Management 
 Aim 
◦ Timely detection of TTTS 
◦ Detection of other complications such as 
selective IUGR, TOPS...
TTTS 
Vascular Anastomoses 
 95% monochorionic placentas have 
these but only 10-15% suffer adverse 
outcomes 
 TTTS and...
Suggested aetiology: cont.. 
 Endocrinal imbalance, donor twin has 
hypovolaemia  RAS activation  
increased ADH  vaso...
TTTS
Quintero Staging System 
Stage I: The fetal bladder of the donor twin remains visible 
sonographically. Discrepancy in AFV...
TTTS: How to diagnose? 
 Can we predict TTTS in first trimester? 
◦ CRL and NT discrepancy at 11-14 weeks: CRL 
discrepan...
TTTS: Ultrasound Features 
 Discordant growth 
 Discordant liquor 
◦ Donor MVP < 2cm 
◦ Recipient MVP > 
8cm 
 +/- disc...
BUT……………… 
 In severe early TTTS, the prominent 
feature is discordant liquor 
Growth may not be 
significantly affected...
Frequency of follow up 
 Booking by 10 weeks 
 At least 9 antenatal appointment 
 At least 2 appointments with speciali...
Why do we need to detect early 
TTTS? 
 If left untreated, fetal mortality can 
reach 80%, survivors face significant 
ri...
Management options of early 
severe TTTS 
Amnioreduction 
Septostomy 
Selective laser ablation of 
communicating vessel...
Management cont.. 
 Amnioreduction: survival rates 60-65% 
 Septostomy: decrease in need to rpt 
procedure and survival ...
TTTS occurs at later part of 
pregnancy: management options 
 Expectant 
 Serial amnioreduction 
Decide timing of 
deliv...
Recommendation (RCOG) 
 Severe TTTS presenting < 26 weeks 
should be treated by laser ablation 
rather than amnioreductio...
Complications of laser 
ablation 
 Most common: PROM (9%) 
 Placental abruption 1% 
 Miscarriage 8% 
NICE March 2006
Monochorionic placenta
Twin Anaemia Polychytemia 
Sequence (TAPS)
Twin Anaemia 
Polychytemia Sequence 
(TAPS) 
 Monochorionic Twin (5%) 
 Spontaneous or after incomplete Laser 
treatment...
Presence of arterial-arterial anastomoses is protective 
against TTTS 
In TAPS: either less A-V anastomoses or more A-A 
a...
TAPS: Antenatal Diagnosis 
 No apparent growth and liquor 
discordance 
 Main feature: discordance in MCA 
blood flow 
...
TRAPS (Twin reversed arterial 
perfusion sequence) 
 Also called acardiac 
twinning 
 High perinatal mortality of 
the n...
Selective IUGR in MCDA 
 Differentiate from TTTS by absence of 
polyhydramnios in one of the amniotic 
sacs, although the...
Discordant Growth* 
 Abdominal Circumference difference > 
20 mm 
 EFW difference > 20%** ( Larger twin as 
a reference)...
Why is MCDA different 
compared to DCDA? 
 Death in one twin may lead to death of 
the other twin 
 Neurological sequela...
Single fetal demise 
 Risk to surviving twin of death or 
neurological abnormality is 12% and 18%, 
respectively 
 Risks...
Subsequent management 
 Detailed counselling and record in case 
notes 
 Rapid delivery is unwise unless there are 
sign...
Management continued…. 
 Plan for brain imaging by 4 weeks to 
establish whether serious cerebral morbidity 
has occurred...
? Intervention to prevent 
concordant fetal demise or 
neurological sequelae 
 If single fetal demise is diagnosed 
early...
Timing of delivery 
 Deliver at 36-37, does not appear to be a/w 
increased risk of serious adverse outcomes 
 Appropria...
Take home 
message!!
MCDA: its all about 
discordance!! 
TTTS Discordant liquor 
Selective IUGR Discordant 
growth 
TAPS Discordant MCA 
PSV 
T...
Reference 
 RCOG 
 ISUOG 
 NICE clinical guideline, Sept 2011, 
Multiple pregnancy 
 StratOG
MCDA Twin Pregnancy
MCDA Twin Pregnancy
MCDA Twin Pregnancy
MCDA Twin Pregnancy
MCDA Twin Pregnancy
MCDA Twin Pregnancy
MCDA Twin Pregnancy
MCDA Twin Pregnancy
MCDA Twin Pregnancy
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MCDA Twin Pregnancy

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MCDA Twin Pregnancy

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MCDA Twin Pregnancy

  1. 1. MCDA Supervisor: Dr Rafaie Presenter: Tan Lee Na 19th September 2014
  2. 2. Are twins good?
  3. 3. Introduction  Both babies share one placenta  1/3 of twins in the UK have MC placentas  Recent increase in multiple pregnancies due to ART  Particular challenges: vascular placenta anastomoses that are almost universal and connect umbilical circulation of both twins
  4. 4. Diagnosis: first trimester Chorionicity and amnionicity: best accuracy in 1st trimester
  5. 5. MCDA
  6. 6. Diagnosis: second trimester A photographic record should be retained
  7. 7. MCDA Bidirectional arterio-arterial anastomosis
  8. 8. If unable to determine chorionicity, treat as monochorionic until proven otherwise
  9. 9. Dating  Use the largest baby to estimate gest age to avoid risk of estimating it from a baby with early growth pathology  Assign nomenclature: transverse (left or right) or vertical (upper or lower)
  10. 10. Management: first trimester  First trimester screening for aneuploidy  Anatomical survey  ?prediction of MCDA complications
  11. 11. First trimester aneuploidy screening:  Offer information: - greater likelihood of T21 in multiple pregnancies - different options for screening (problem with biochemical screening) - false positive rates of screening tests are higher in multiple pregnancies - higher rate of complications of invasive tests (threshold for invasive test is higher) - implications relating to selective fetal reduction
  12. 12. Aneuploidy screening  1st trimester screen: combined test (NT + bHCG + PAPP-A)  Calculate the risk per pregnancy for monochorionic twins (as opposed to risk per baby for dichorionic twins)  If unable to do, consider 2nd trim serum screening, however potential problems arise such as double invasive testing because risk of T21 cannot be calculated separately for each baby
  13. 13. Subsequent Management  Aim ◦ Timely detection of TTTS ◦ Detection of other complications such as selective IUGR, TOPS, TRAPS, single fetal demise
  14. 14. TTTS Vascular Anastomoses  95% monochorionic placentas have these but only 10-15% suffer adverse outcomes  TTTS and TRAP are the most well recognised complications  Suggested aetiology: deep anastomoses within placental mass are usually btwn arteries and veins which allow unidirectional blood flow
  15. 15. Suggested aetiology: cont..  Endocrinal imbalance, donor twin has hypovolaemia  RAS activation  increased ADH  vasoconstriction oliguria and AF  Recipient twin: hypervolaemia  atrial natriuretic peptide  polyuria and  AF, also BP leading to cardiac failure and hydrops, eventually death
  16. 16. TTTS
  17. 17. Quintero Staging System Stage I: The fetal bladder of the donor twin remains visible sonographically. Discrepancy in AFV with MVP ≤2 cm in one sac and MVP ≥8cm (<20 weeks) or ≥10 cm (>20 weeks) in the other sac Stage II: The bladder of the donor twin is collapsed and not visible by ultrasound. Stage III: Critically abnormal fetal Doppler studies noted. This may include absent or reversed end-diastolic velocity in the umbilical artery, absent or reverse flow in the ductus venosus, or pulsatile flow in the umbilical vein. Stage IV: Fetal hydrops present. Stage V: Demise of either twin.
  18. 18. TTTS: How to diagnose?  Can we predict TTTS in first trimester? ◦ CRL and NT discrepancy at 11-14 weeks: CRL discrepancy marker for subsequent sFGR, NT discrepancy not predictive ◦ NT: discordance >20% shows risk of severe TTTS is > 30%, if <20% then risk of TTTS < 10% ◦ CRL: discordance >10% predictive of early onset disease <20 weeks ISUOG 6 Oct 2010: Intertwin CRL discrepancy in MC twins is an early feature of GR rather than TTTS 20 Apr 2007: Discordance in NT in the prediction of severe TTTS 31 Aug 2006: First trimester discordance in CRL predicts timing of development of TTTS
  19. 19. TTTS: Ultrasound Features  Discordant growth  Discordant liquor ◦ Donor MVP < 2cm ◦ Recipient MVP > 8cm  +/- discordant bladder size  +/- abnormal doppler in one or both twin.  +/- fetal hydrops or fetal demise
  20. 20. BUT………………  In severe early TTTS, the prominent feature is discordant liquor Growth may not be significantly affected in early pregnancy
  21. 21. Frequency of follow up  Booking by 10 weeks  At least 9 antenatal appointment  At least 2 appointments with specialist obstetricians  Dating scan followed by scans at 16,18,20,22,24,28,32,34 weeks
  22. 22. Why do we need to detect early TTTS?  If left untreated, fetal mortality can reach 80%, survivors face significant risk of long term cardiac, renal and neurological sequelae  Timely intervention can save lives!!! (one or both babies)
  23. 23. Management options of early severe TTTS Amnioreduction Septostomy Selective laser ablation of communicating vessels
  24. 24. Management cont..  Amnioreduction: survival rates 60-65%  Septostomy: decrease in need to rpt procedure and survival rate similar, however risk of inter-twin cord entanglement  Laser ablation: most logical therapeutic approach, placental vessels traced endoscopically from origins and ablate all anastomoses, survival rate 70-81%, consider in ALL stages of TTTS to improve perinatal outcome
  25. 25. TTTS occurs at later part of pregnancy: management options  Expectant  Serial amnioreduction Decide timing of delivery!
  26. 26. Recommendation (RCOG)  Severe TTTS presenting < 26 weeks should be treated by laser ablation rather than amnioreduction or septostomy  Little information about maternal morbidity after laser  Suggestion: USG (brain imaging, fetal measurement, doppler) at least weekly, consideration to deliver at 34 weeks, usually by CS
  27. 27. Complications of laser ablation  Most common: PROM (9%)  Placental abruption 1%  Miscarriage 8% NICE March 2006
  28. 28. Monochorionic placenta
  29. 29. Twin Anaemia Polychytemia Sequence (TAPS)
  30. 30. Twin Anaemia Polychytemia Sequence (TAPS)  Monochorionic Twin (5%)  Spontaneous or after incomplete Laser treatment for TTTS  Same pathology as TTTS (Milder form)  Large intertwin hemoglobin differences in the absence of amniotic fluid discordances  Usually in 3rd trimester.
  31. 31. Presence of arterial-arterial anastomoses is protective against TTTS In TAPS: either less A-V anastomoses or more A-A anastomoses
  32. 32. TAPS: Antenatal Diagnosis  No apparent growth and liquor discordance  Main feature: discordance in MCA blood flow  MCA Peak systolic velocity measurement (PSV) ◦ Moderate to severe anaemia: PSV MoM > 1.5 ◦ Polycythaemia: PSV MoM < 0.8 Even in apparently uncomplicated MCDA, it is advised to do MCA doppler in every patient after 24 weeks
  33. 33. TRAPS (Twin reversed arterial perfusion sequence)  Also called acardiac twinning  High perinatal mortality of the normal ‘pump’ twin due to CCF and hydrops  Treatment: ◦ Expectant ◦ Cord occlusion of the acardiac twin if show evidence of heart failure in the pump-twin
  34. 34. Selective IUGR in MCDA  Differentiate from TTTS by absence of polyhydramnios in one of the amniotic sacs, although the small twin may have oligohydramnios owing to placental insufficiency  Scans after 24 weeks to detect fetal growth restriction
  35. 35. Discordant Growth*  Abdominal Circumference difference > 20 mm  EFW difference > 20%** ( Larger twin as a reference)  BPD > 6 mm  FL > 6 mm * Usually accompanied with abnormal UA doppler ** Latest evidence suggests that difference by 18% is significant
  36. 36. Why is MCDA different compared to DCDA?  Death in one twin may lead to death of the other twin  Neurological sequelae in surviving twin Importance of close monitoring and timely decision for delivery!!! • try to achieve good survival of both fetuses • at least survival of one fetus with minimal neurological sequelae
  37. 37. Single fetal demise  Risk to surviving twin of death or neurological abnormality is 12% and 18%, respectively  Risks are not restricted to MC pregnancies with a prior diagnosis of TTTS  Caused by acute haemodynamic changes around time of death, as survivor haemorrhaging part of its circulating volume into the circulation of the dying twin leading to hypotension and low perfusion and eventually ischaemic end organ damage
  38. 38. Subsequent management  Detailed counselling and record in case notes  Rapid delivery is unwise unless there are significant CTG abnormalities or evidence of anaemia in the survivor (MCA doppler) or if fetal death occurs late in pregnancy  Evidence of fetal compromise could represent continuing damage to the brain and other organs, therefore conservative management is often appropriate
  39. 39. Management continued….  Plan for brain imaging by 4 weeks to establish whether serious cerebral morbidity has occurred as such manifestation on CNS are variable and takes up to 4 weeks to occur  Fetal MRI provides earlier and more detailed information about brain lesions than USG  If pre-viable: TOP is an option  Timing of delivery: 34-36 weeks
  40. 40. ? Intervention to prevent concordant fetal demise or neurological sequelae  If single fetal demise is diagnosed early: intrauterine fetal blood transfusion of the surviving twin may be considered
  41. 41. Timing of delivery  Deliver at 36-37, does not appear to be a/w increased risk of serious adverse outcomes  Appropriate to aim for vag birth unless there are accepted, specific clinical indications for CS eg twin one lying breech or previous CS  60% of twins: spontaneous birth before 37 weeks  Prolonging pregnancy beyond 38 weeks increases risk of fetal death  If elective birth declined, offer weekly appointment with specialist obstetrician, offer USG at each visit and perform biweekly biophysical profile assessments, fortnightly fetal growth scans
  42. 42. Take home message!!
  43. 43. MCDA: its all about discordance!! TTTS Discordant liquor Selective IUGR Discordant growth TAPS Discordant MCA PSV TRAPS/discorda nt fetal anomalies discordant fetal anomalies
  44. 44. Reference  RCOG  ISUOG  NICE clinical guideline, Sept 2011, Multiple pregnancy  StratOG

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