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Obstetrics > Multiples > Flashcards

Multiples Flashcards

1
Q

What are the risks of death of one twin

+ the rates of each

A

Co twin demise
6X higher in MC (12% vs 4%)

Premature delivery
MC before 34/40 70%
DC 60%

Neurological impairment
thromboplasin theory
ischemic theory
present 6 days to 6 weeks

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2
Q

How often does death of one twin occur?

in T1 vs T2/3
In MC vs DC

A

T1 - vanishing twin
25% twins at 6/40 will not be there at 12/40

T2/3
MC losses 4-11%
DC losses 1-5%

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3
Q

What is the etiology of 1 twin death in
DCDA
MCDA
MCMA

A

DCDA
FGR (esp in discordance 30%)
PET (can help)
Other normal things abruption, GDM, abnormalities

MCDA
TTTS 50% 
Unexpected 1-6%
sIUGR
Fetal abnormalities 
TRAP (rare)
Iatrogenic 
MCMA 
50% cord entanglement 
Fetal abnormalities 25% 
(usually discordant) 
TTTS less common
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4
Q

What are the signs a surviving twin has neurological damage

Present 6/7 to 6/52

A 
Periventricular leukomalacia 
Multicystic encephalomalacia 
Porencephaly 
Hydrancephaly  
Microcephaly
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5
Q

Management

What is the general management for 1Twin demine

A

Steroids
MgSO4
Paediatric consult
If the live twin is normally grown, cephalic and leading then vaginal delivery can be considered
If the dead twin in leading or malpresentation then caesarean is recommended
Risk of DIC if more then 4 weeks is very low but can consider weekly fibrinogen / platelet / PT
Full coags before regional anesthetic or delivery
Psychological support

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6
Q

Timing of delivery + specific management with 1 twin demised
DCDA
MCDA
MCMA

A

Steroids
MgSO4
Paediatric consult
DIC monitoring

DCDA
delay until 34 weeks
Serial USS growth doppler CTG

MCDA
Likely neurological injury already occurred
Weekly USS
MRI 3/52 after death 
If abnormal talk to paeds / TOP 
Anaemia with abn PSV poor prognosis

MCMA
Delivery by 28 weeks
Rare, usually both demise

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7
Q 
What is the risk of twin pregnancies of:
CP
Congenital abnormalities
infant death
Spont PTB 
IUGR
A 
CP is 4-8 X higher
1.5/1000 singleton
7:1000 Twins 
30:1000 triplets  
Congenital abnormalities
12X increased risk congential heart defects
70% twin not effected
Major abnormalities in 5% 
Spont PTB  50%
IUGR
25% MC pregnancies
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8
Q

What are the maternal risks of a twin pregnancy ?

A 
Hyperemesis 
Anaemia 
Gestational diabetes 
PET 
Operative delivery 
LSCS 
Social emotional impact of having twins  
PTB 
PPROM

Post natal depression
Divorce

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9
Q

How to dx twins on early USS

A

Early ultrasound scanning

Dx by 11-14 weeks
DCDA – Twin peak sign
MCDA – T sign

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10
Q

MOD for twins

A

The twin birth study – Toronto
If T1 is cephalic, and after 32 weeks then planned VB is best practice (level 1 evidence)
If experienced operator is in attendance
40% EMLSCS rate
Increase resp disease in ELLSCS

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11
Q

At delivery what is the risk to T2
Mortality
LSCS risk
outcomes

A

EMLSCS for T2 4-10%
Delivery related death of T2 is 1:300

Overall poorer outcomes T2

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12
Q

What timing of splitting causes what types of twins ?

A

Depends on timing of splitting
D0-3
DCDA twins as 2 embryos amnions and chorions develop
2 placentas or a single fused placenta may develop

D4-8
MCDA

D8+
MCMA

D13+
Conjoined

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13
Q

Are all monozygous twins monochorionic?

A

Monozygous twins

Can be MCMA
Most are MCDA 1/400 pregnancies
1/9 are DCDA = in same sex DCDA twins zygosity cannot be determined without DNA sampling as could be early splitting

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14
Q

Why is the number of twins going up?

A

Rate of multiple pregnancy is affected by
Maternal age, ethnicity, parity
Use of ART
Monozygotic twinning is pretty stable
2% of all births are multiples
Reduction in ART associated multiple pregnancies
20% of multiples are related to ART

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15
Q

What % of twins are monoamniotic

A

1%

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16
Q

What is the rate of cord entanglement

A

Most common cause of fetal death
Risk of death increases by 2% every week from 15 weeks
30% by 30 weeks
Delivery planned by 32 weeks (RCOG says delivered by 32-34 weeks by LSCS)
Prediction based on USS or CTG has been suggested but no good evidence and risk of false positive and PTB

17
Q

What is the diagnosis of TTTS

A

Diagnoses
one twin SDP less then 2, and recipient SDP over 8
Can have abnormal dopplers
Assess for hydrops including cardiomegaly, ascites, oedema, abnormal ductus venosus

so occur in monoc

18
Q

What are the 2 types of TTTS

A

TOPS
Twin oligohydramnios / polyhydramnios Sequence
10% of MC twins
Seen midtrimester
‘classical’ TTTS
this is usually 10-15% unbalanced transfusion

TAPS  
Twin Anaemia/ Polycythemia Sequence  
5% of MC twins  
10% of twins post lazer treatment 
Slow transfusion 5-15 ml / 24 hours from donor to recipient

MCA above 1.5 MoM in one and below 0.8 In the other

Large Hb discordance without amniotic fluid discordance

19
Q

Risks of TTTS

A 
SRM + PTB from Poly 
Cardiac failure 
Hydrops 
Death of one twin
- 50% co twin survival 
- 50% deficit - loss of the co twin (25%) or significant long term neurological deficit (25)

Prematurity
Neurological damage - can assess for ventriculomegaly

IUGR
20% but fetal size is not part of the diagnostic criteria or staging criteria

20
Q

Stages TTTS

A

Stage 1: donor bladder visible, EDF positive in both vessels in both fetuses.

Stage 2: donor bladder not visible, EDF positive in both vessels in both fetuses.

Stage 3: EDF absent or reversed in either vessel in either fetus.

Stage 4: presence of ascites or hydrops in either fetus; usually the recipient.

Stage 5: fetal Death

21
Q

Management TTTS

A

Conservative
Poor outcome unless stage 1
40% of stage one can stabilise and resolve
USS weekly

Amnioreduction not as successful as laser and can make later laser more difficult - may have a role in late onset

Laser
16-28 weeks 
Median age 21 weeks
Deliver by 34-36+6 
Weekly USS
22
Q

What are the risks with laser for TTTS

A

Risks:
PPROM
PTL 10-15% within 2 weeks of the procedure
Loss of one or both twins – overall survival 75%, survival of both twins 66%
Neurological damage – close MRI surveillance
Monitor for IUGR + TAPS as still unequal sharing of the placenta
Solomon technique is lazering the placenta to dichorionise it – this reduces but doesn’t remove the TAPS risk

23
Q

Selective termination

How do you do it

A

Especially if one twin have a major anomaly / neurological damage
Selective feticide by intravascular injection of an abortifacient is not an option in monochorionic pregnancies because of the presence of placental anastomoses. The potential risks of intrafetal/umbilical cord ablative procedures should be discussed prospectively, including the risk of co‐twin loss and neurological morbidity.

Monitoring for disseminated intravascular coagulopathy is not indicated in monochorionic twin pregnancies undergoing selective reduction.

24
Q

Long term sequalae of PTB

A 
RDS 
Ventilatory assistance 
Chronic lung disease 
Hypotension needing inotropes 
Oliguric renal failure  
Neurodevelopmental disability 
Serial amnioreduction – disability 20% 
Laser – 4-13% overall impairment up to 18%  
Severity at diagnosis relates to long term outcomes 
Long term paeds follow up
25
Q

What is TRAPS

A

Twin reversed arterial perfusion (TRAP) sequence refers to a rare complication unique to monochorionic twin pregnancies in which a twin with an absent or rudimentary heart (“acardiac twin”) is perfused by its co-twin (“pump twin”) via aberrant arterio-arterial anastomoses.

The acardiac twin is wholly dependent upon circulatory support from the pump twin, and its upper body and head are often poorly developed, if not altogether absent. Thus, the acardiac twin has no potential for ex utero survival

26
Q

How common is TRAPS

A

A 2015 study estimated the incidence of TRAP sequence to be 2.6 percent of monochorionic twin pregnancies and 1 in 9500 to 11,000 pregnancies

27
Q

sIUGR for MC twins

Definition
Who follows
Treatment
What dopplers when
When to deliver
A

More then 20% discrepancy
MFM FU
If early onset, with poor growth velocity selective reduction can be considered

Surveillence every 2 weeks – doppler and growth – once UAPI is abn then for DV

Indications for delivery should include abn DV (reversed flow during the atrial contraction) or abnormal CTG

Type 1 sGR
Planned delivery 34-36 weeks (if normal dopplers and satisfactory fetal growth velocity)

Type 2 and 3 – delivery by 32 weeks unless velocity is significantly abnormal or worsening of the doppler assessment

28
Q

What should the plan for routine growth scans be?
For DCDA

MCDA

A

DCDA
4 weekly from 24 weeks

MCDA
2 weekly from 16 weeks - 24 weeks screening for TTTS
THEN 4 weekly growth from 24 weeks

29
Q

How to perform aneuploidy screening in twin pregnancies

A

T1 Nuchal -
Early anatomy with Nuchal
Discordant nuchal in monochorionic twins increases the risk of TTTS
Increase False positives in NT with monochorionic for trisomy screening

MSS 1 sensitivity DC 86 percent MC as 87 %

Detailed anatomy scan at 20 weeks

NIPT
Validated with twins (any sort)
99% sensitivity for T21
85% sensitivity for T18

Over 5%get no result - unable to process

30
Q

When screening for TTTS 16-24 weeks what to look for on scan

A 
Growth 
Amniotic fluid volume 
Bladder volume 
Umbilical artery  
After 20 weeks – MCA
31
Q

Routine care for twin pregnancies also need to include

A

High dose folic acid as increased fetal demands of folate
Iron supplementation - maintain Hb as increased PPH risk
GDM Screening
Screen for antenatal and postnatal depression – high risk and anxious time, offer supports
High risk for PET – BP and urine dip at each visit

32
Q

Timing of delivery for uncomplicated twin pregnancies

A

NICE Guideline
Monoamniotic
From 32 weeks by ELSCS

Monochorionic
From 36 weeks

Dichorionic
From 37 weeks (RANZCOG magazine 38 weeks)
‘normal’ twin pregnancies with none of the above – aim 37-38 weeks
Cochrane review showed no benefit 37 weeks to later gestations

Triplets
From 35 weeks

33
Q

How to plan vaginal delivery for twins

What is needed

A

Location
Access to paeds /theatre
Access to anaesthetics

Staffing
Experienced practitioner
Additional midwifery and pediatric staff
Anaesthetic review

Intervention / preparation
IVF + Hb + Cross match
Epidural is recommended (must discuss the benefit of facilitating T2 delivery)

Monitoring
CEFM for both twins

Delivery  
Portable USS 
Breech T2 is safer then ECV  
No defined intertwin delivery times  
Oxytocin to maintain uterine inertia

Postnatal
Active management of third stage
Prophylactic infusion of oxytocinon

34
Q

How to care for woman and twins post natally

A

If same sex, DCDA twins zygosity is not able to be determined without genetic testing
Parent support groups recommend this

Twins should be examined for structural and chromosomal abnormalities
FBC – check Hb especially if had TTTS or TAPS
Cranial Ultrasound if had TTTS TAPS or TRAPS
If had any other the above refer to a developmental pediatrician for follow up

Screen for postnatal depression + support ongoing supports

35
Q

How to calculate discordant growth of twins

A

Calculate percentage EFW discordance using the following formula: ([larger twin EFW – smaller twin EFW]/larger twin EFW) x 100

Discrepancy more then 20% refer MFM

Obstetrics (41 decks)

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