Multiple pregnancy file

Multiple pregnancy for MRCOG

Multiple birth UK 1995
No. (Rate/1000 mats) Ratio
Twins 9889 (13.6) 1 in 73
Triplets 318 (0.4) 1 in 2282
Quads 10 (0.0001) 1 in 72563
Total 10217 (14) 1 in 71

Importance of chorionicity?
Chorionicity affects pregnancy risk:
Fetal loss rates
Cerebral palsy rates
Pregnancy risk assessment
Twin-twin transfusion syndrome
Prenatal diagnosis
Chromosome abnormality
Strucural abnormality
Further schedule of surveillance based on chorionicity (?=delivery mode)

Prevalence death & cerebral palsy Western Australia 1980-1989

Fetal and Perinatal Mortality Fetal Loss (<24 weeks) Perinatal Loss (>24 weeks) Sebire N et al. BrJOG 1997 12.1% 1.8% 2.8% 1.6% Monochorionic Dichorionic

Presumed zygosity & cerebral palsy ( Western Austailia 1956-1985) P=0.0026 Concordant Discordant Monozygotic 6 9 Dizygotic 0 21

Chorionicity versus zygocity 0-4 days 4-7 days 7-14 days Fused or unfused

Early ultrasound appearances
Scans before 11 weeks common in AC pregnancies
Chorionicity:
2 clear sacs dichorionic
?1sac monochorionic
Amnionicity:
Uncertain
Yolk sac number
Dichorionic twins (7 weeks)

Ultrasound diagnosis of chorionicity
 “ T” sign
MONOCHORIONIC
 “ Lambda” sign
DICHORIONIC

Twin-twin transfusion syndrome
25% MC twins will have evidence of TTS at 15-17 weeks
50%  severe TTS
Severe TTS 80-90% mortality
Death will occur in both babies
Recipient
Donor

Indicators of risk of TTTS
11-13 week scan
Discrepancy in CRL
Discrepancy in NT
Donor small NT
Receipient raised NT
16 week scan
Infolding of the membranes
Size discrepancy

Diagnosis of chronic TTTS Monochorionic Stuck twin Polyhydramnios Growth discrepancy Doppler Hydrops PROGRESSIVE*

Serial Amniodrainage
Multicentre Registry (Mari et al. 1998)
579 cases
Survival 68%
Abnormal neonatal head sonograms - 25%
Normalise amniotic fluid volume
Improves uterine blood flow
Prevents premature labour

Fetoscopic Laser Ablation Ville et al. 1998 BrJOG DiLia 1998 (TTTS website) Non-selective Laser Ablation 202 cases 59% Survival 4% neurological handicap rate

FLA vs Amniodrainage n=116, 17-25 weeks’ gestation n=43: Amniodrainage, Bonn; n=73: Laser ablation, Hamburg Hecher K et al. 1999 AmJOG Overall survival (NS) 61% 51% FLA Abnormal brain scan (p <0.03) 6% 18% FLA FLA Amnion Drainage Gestation at delivery (p <0.02) 33.7 30.7

TTS in the 3rd trimester?
REMEMBER
Chronic type TTS
Acute “late onset” TTS
Antenatal
Intrapartum
Delivery of twin 1

Mono-amniotic twins
High mortality rates (upto 50%)
TTTS/Discordant growth unusual
Monitor amniotic fluid volume
Colour-flow doppler for cord entanglement
Monitoring of uncertain value
Delivery at 32-34 weeks?

Prenatal diagnosis in twins
Screening
Nuchal translucency
Serum screening
Invasive diagnosis
Chorionic villous sampling
Amniocentesis

Screening for aneuploidy in twins
Calculation of risks
For each fetus
For the pregnancy
NT screening
Biochemical screening
Risks of intervention
Invasive procedure
Selective fetocide

Single puncture amniocentesis Sebire et al 1996 Miscarriage risk 1-2% Selective fetocide 8%+ Sample one sac in MC Careful documentation

CVS in twins
Single or double entry
Experienced operator
Careful documentation
Sample 1 placenta in MC twins
Miscarriage risk
1-2%
Risk of selective fetocide
11-13 weeks 5%
CVS for “high risk”

Twins and fetal abnormality
Dichorionic
Same risk doubled
Monochorionic
“ Teratogenic” stimulus
Increased risk midline abnormalities
Not always cordant
Specific twin abnormalities

Conjoined twins

Acardiac twinning

Scanning schedule- normal
Monochorionic
12 weeks
16 weeks
20 weeks
24 weeks
27 weeks
30 weeks
33 weeks
Delivery 36 weeks
Dichorionic
12 weeks
20 weeks
28 weeks
32 weeks
36 weeks
Delivery 38 weeks
Increased surveillance if evidence of TTTS or growth abnormality

Low birthweight a Singleton b Twins c Triplets d quads 52% twins (n=5416) <2500g compared 6% singletons ( Regan 2001)

Delivery of pre-term twins 37

Elective delivery of twins Sairam et al 2002

Delivery mode?
Chorionicity
Monochorionic
Mononamniotic
Presentation and lie
Breech twin 1
Fetal/maternal complications
Preterm labour
Growth restriction
Previous caesarean section
Elective delivery
Consider

Delivery monochorionic diamniotic?
No evidence
Elective LSCS
Allows early delivery (36-37 weeks)
Avoids late onset TTTS
Avoids “circulatory charge” T2 after T1 delivered
Small number of absolute total of twins
Vaginal delivery
No antenatal evidence TTTS
Favorable cervix (multips)
Limit delivery interval
Monitor T2 carefully

Presentations of twins FIRST TWIN SECOND TWIN Percentage of presentation combinations in labour Cephalic Breech Other Cephalic 38.6 13.1 0.6 Breech 25.5 9.2 0.6 Other 8.0 3.9 0.5

Breech twin 1
Prevalent practice =LSCS
ACOG recommends LSCS
Reasons sited
Interlocking twins (1 in 90)
Interference with decent of breech
Term breech study (irrelevant)
Lack of experience
Vaginal delivery maybe safe in selected cases
EFW1500-3500
US no interlocked heads
No IUGR
Non-footling breech

Weight difference in twins Audit data SHH 1998 N=45 Twin 1 is not usually bigger than twin 2

Evidence based medicine & twins?
Observational and non-randomised comparative studies
Address controversy :
mode of delivery of twin 2
time interval between delivery of T1 andT2
ECV vs breech extraction
Trial of scar in twin pregnancy
Problem:
retrospective studies
inappropriate measures of outcome
recommendations are often empirical

Delivery of growth restricted twins
30-50% IUGR
Progressive
Beginning 32-34wks
Worse after 36wks
Offer IOL at 38wks
Earlier if severe IUGR
Doppler assessment
Delivery mode
EFW
Severe discordance (>20%)

Vertex/vertex
Literature supports vaginal delivery
5% cases T2 will become non-vertex after delivery T1
Report 81% success
Differences of opinion
?  Perinatal morbidity
Concerns
Head entrapment
Overall evidence suggests vaginal delivery is as safe as LSCS
Vertex/breech

VTX/Non-VTX >2000g <24 weeks ECV T2 Successful >24wks & <2000g Vaginal T1 *Vaginal breech T2 Vaginal T1&T2 *Vaginal breechT2 Probable vaginal T2 Vaginal T1 ECV T2 Unsuccessful Unsuccessful Successful LSCS LSCS Probable vaginal T2 *Suitable for vaginal breech

Recent evidence?
Retrospective 92-97
Scotland
All twin births >24 weeks
Excluding
pre-labour IUD
Congenital abnormality
PRETERM (vaginal)
1438 twin pairs <36/40
23 deaths T1
23 deaths T2
Pulmonary & anoxia
TERM (vaginal)
2436 twin pairs >36/40
No deaths T1
9 deaths T2
7 deaths due to anoxia
5 “mechanical” problems
TERM (elective LSCS)
454 twin pairs
No deaths T1 or T2
Conclusion Planned caesarean birth may prevent perinatal deaths BUT Chorionicity unknown (7 of 9 T2 deaths were concordant for sex ie. may be monochorionic) Smith et al 2002, BMJ

Twin vaginal birth after LSCS
Controversial limited data about safety
Concern ?  risk of uterine rupture
Over-distention
Intrauterine manipulations
No evidence of risk
3 studies no increased risk
Other caused of over-distention no  risk
Trial of labour at maternal request

Analgesia
Appropriate analgesia essential
Operative delivery may be required
Increased risk of GA
Prophylactic antacids
Anaesthetist available on LW
Epidural optimizes vaginal delivery (recommended)
Epidural not mandatory
Nitrous oxide
Opiates

Issues in monitoring twins
“ High risk”  EFM
Continuous & simultaneous
External transducer T2
FSE T1 after ROM
Ensure 2 heartbeats seen
Careful monitoring after delivery of T1 (ultrasound aids transducer positioning)

‘ The Delivery’ - Twin 1
Encourage active pushing
Semi-recumbent position once T1 crowning
Episiotomy as necessary
Clamp & mark cord T1
Ventouse or forceps

‘ The Delivery’ - Twin 2 ECV versus Breech delivery versus Internal podalic version Palpate lie immediately after delivery T1

‘ The Delivery’ - Twin 2
Start syntocinon infusion once T2 cephalic
Escalate dose at 5 minute intervals
Await contractions & PP to stabilized above pelvis
ARM
FSE if poor external CTG
Ventouse
Breech extraction
?Delivery interval

Combined vaginal-abdominal delivery Misfortune or mismanagement?
Increasing incidence 1-15% LSCS T2
Higher rate elLSCS in twins   LSCS for T2
Operator experience
Some management issues
Justified
Failed version in transverse lie
SROM-shoulder presentation
Cord prolapse (especially prems)
Large T2
?Fetal distress with high presenting part

Delayed delivery interval
Caution:
isolated case reports
publication bias
Consideration:
gestation
chorionicity
maternal informed consent

Delayed delivery interval
48 twin pregnancies
40/96 surviving infants (39=T2)
Interval 3 - 143 days
mean 44.8 days
No consensus on treatment strategy
Obs & Gyn Survey 1999: 54,343-8

‘ The delivery’ - third stage
Active management
Syntocinon 5 units (IV or IM) after delivery of second twin
Syntocinon infusion after delivery of placenta

UK birth rate of Triplets

Higher multiples-?chorionicity
Can be:
Trichorionic
Dichorionic
Triamniotic
Diamniotic
Monochorionic
Tri-amniotic
Monoamniotic (rare)
Scan early
Scan often

Multiple pregnancy file

by barryjohnwhitlow

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