Twin/Multiple pregnancy (Obstetrics).ppt

Multiple pregnancy Twin pregnancy obs

1. Multiple pregnancy

2. Incidence:
Incidence of multiple pregnancy was rising, but now
appears to be stable at:
twins—15:1000
triplets—1:5000
quadruplets—1:360 000.
Higher multiples than this are extremely rare, but do occur:
a surviving set of quintuplets was born in the UK in 2007.

3. Aetiology:
Multiple predisposing factors including:
Previous multiple pregnancy.
Family history.
Increasing parity.
Increasing maternal age:
<20yrs: 6:1000
>35yrs: 22:1000
 >45yrs: 57:1000.

4. Cont..
Ethnicity:
Nigeria: 40:1000
Japan: 7:1000.
 Assisted reproduction
1.incidence of multiple pregnancy with clomiphene—10%
2. intrauterine insemination (IUI) 10–20%
3.IVF with 2-embryo transfer—20–30%.
 In an attempt to decrease this complication, the Human Fertilization and
Embryology Authority (HFEA) recommend that no more than two embryos
should be transferred per IVF cycle.

5. Types
 Dizygotic twins:
result from two separate ova being
fertilized by different sperm,
simultaneously implanting and
developing.

Monozygotic twins
result from division into two of a single,
already developing, embryo and
will be genetically identical and,
therefore, always the same sex.

6. Dizygotic Monozygotic
Consequently, these fetuses will have
separate amniotic membranes and
placentas (dichorionic and diamniotic—
DCDA).
 Twins may be different sexes. This
mechanism of twinning accounts for
2/3of multiple pregnancies;
 this type is most affected by
predisposing factors, such as age and
ethnicity.
Whether they share the same amniotic
membrane and/or chorion depends on
the stage of development when the
embryo divides.
 About two-thirds are monochorionic
diamniotic.
The worldwide monozygotic twining rate
appears to be constant at about 3.5 per
1000.
However, the rate is slightly greater than
expected with IVF treatment.

7. Timing of division in monozygotic twins:
 <3 days = DCDA 30%.
 4–7 days = monochorionic, diamniotic (MCDA) 70%.
8–12 days = monochorionic, monoamniotic (MCMA) <1%.
>12 days = conjoined twins (very rare).

8. Diagnosis
 There are several signs and symptoms associated with
multiple pregnancy including:
1. Hyperemesis gravidarum.
2.Uterus is larger than expected for dates.
3.Three or more fetal poles may be palpable at >24wks.
4. Two fetal hearts may be heard on auscultation.
5.However, the vast majority are diagnosed on ultrasound
in the 1st trimester (at a dating or nuchal translucency
scan).

9. Chorionicity:
 Determining chorionicity allows risk stratification for multiple pregnancy
and is best done by ultrasound in the 1st trimester or early in the 2nd.
 The key indicators are:
1.Obviously widely separated sacs or placentae—DC.
2. Membrane insertion showing the lambda ( λ) sign—DC.
3. Absence of λ sign <14wks diagnostic of MC.
4. Fetuses of different sex—DC (dizygotic).

11. Antenatal care:
All multiple pregnancies “high risk’ and the care should be consultant led.
 Establish chorionicity—most accurately diagnosed in 1st trimester
 Routine use of iron and folate supplements should be considered.
A detailed anomaly scan should be undertaken.
 Advise aspirin 75microgram od if additional risk factors for: pre-eclampsia.
Serial growth scans at 28, 32, and 36wks for DC twins.
More frequent antenatal checks because of increased risk of pre-
eclampsia.

12. Cont:
Discuss mode, timing and place of delivery.
Establish presentation of leading twin by 34wks.
 Offer delivery at 37–38wks
Induction or lower segment Caesarean section (LSCS).
Surveillance needs to be more intensive for MC twins particularly <24wks, or
higher multiples, so referral to a specialist fetal medicine team

13. Maternal risks:
The risks of pregnancy appear to be heightened with twins compared with
singletons, leaving mothers at increased risk of:
1.Hyperemesis gravidarum.
2.Anaemia.
3. Pre-eclampsia (5 × greater risk with twins than singletons).
4.Gestational diabetes.
5.Polyhydramnios.
6. Placenta praevia.
7.Antepartum and post-partum haemorrhage.
8. Operative delivery.

14. Fetal risks:
All fetal risks increased with MC twins.
1.Risk of miscarriage : especially with MC twins.
2.Congenital abnormalities more common only in MC twins including:
 neural tube defects
 cardiac abnormalities
 gastrointestinal atresia.
 IUGR: up to 25% of twins.

15. Cont..
Preterm labour: main cause of perinatal morbidity and mortality:
1.40% twins deliver before 37wks
2.10% twins deliver before 32wks.
Perinatal mortality:
1.singletons 5:1000
2.twins 18:1000
3. triplets 53:1000.

16. Cont..
Risk of intrauterine death (stillbirth):
1.singletons 8:1000
2. twins 31:1000
3. triplets 84:1000.
 Risk of disability (mainly, but not entirely, due to prematurity and low birth weight).
Incidence of cerebral palsy (CP):
1.singletons 2:1000
2.twins 7:1000
3. triplets 27:1000.
 Vanishing twin syndrome: one twin apparently being reabsorbed at an early gestation
(1st trimester).

17. Monochorionic,diamniotic twins:
The shared circulation of MC twins can lead to several
problems.
1. Twin-to-twin transfusion syndrome (TTTS)
This affects about 5–25% of MC twin pregnancies and
left untreated has an 80% mortality rate.
 It may occur acutely at any stage or more commonly
take a chronic course, which, at its worst, leads to
severe fetal compromise at a gestation too early to
consider delivery.

18. Cont..
It is caused by aberrant vascular anastamoses within the placenta, which
redistribute the fetal blood.
Effectively, blood from the ‘donor’ twin is transfused to the ‘recipient’ twin.
MC twins require intensive monitoring, usually in the form of serial USS every
2wks from 16–24wks and every 3wks until delivery.

19. Cont..
This is best performed in a specialist fetal medicine unit.
The treatment options potentially available include:
Laser ablation of the placental anastamosis. This method is
associated with lowest risk of neonatal handicap.
Selective feticide by cord occlusion is reserved for refractory
disease.
TTTS managed by laser treatment leads to survival of at least
one in 80% and both in 50% Selective intrauterine growth
restriction

20. Selective IUGR
 Growth discordance, even without TTTS, is more common.
A very variable pattern of umbilical artery Doppler signals (intermittent
absent/reversed end diastolic flow:
1.AREDF indicates a high risk of sudden demise.
 Treatment: if >28wks—delivery is safest;
if <28wks, selective termination or laser ablation should be considered.

21. Termination of pregnancy issues
Termination of pregnancy issues. Although MC twins may be discordant for
structural abnormalities, genetically they are identical.
Selective termination of pregnancy requires closure of the shared
circulation so is normally performed using diathermy cord occlusion

22. Twin reversed arterial perfusion
syndrome (TRAP)
 In this rare condition, one of an MC twin pair is structurally
very abnormal with no or a rudimentary heart, and
receives blood from the other (umbilical artery flow
direction is reversed), which is called the ‘pump twin’.
This normal twin may die of cardiac failure, and unless the
abnormal twin is very small or flow to it ceases, selective
termination using radiofrequency ablation or cord
occlusion is indicated.

23. Labor
For labour, the leading twin should be cephalic, and there should be no
absolute contraindication (e.g. placenta praevia).
Triplets and higher-order multiples are usually delivered by CS.
some authorities advise CS for MC twins.

24. Management of labor and delivery:
 Twins are usually induced at 38wks gestation, but many will have delivered
spontaneously before then.
The woman should have IV access and a current Group and Save.
 Fetal distress is more common in twins;
o continuous fetal monitoring with CTG is important throughout labour.This
becomes imperative after the first twin has delivered to avoid hypoxia in the
second.
o It may be helpful to monitor the leading twin with a fetal scalp electrode and
the other abdominally.
oAn epidural may be helpful, especially if there are difficulties delivering the
second twin, but is not essential.

25. Cont..
Many units choose to deliver twins in theatre as there is more space
available and it provides immediate recourse to surgical intervention if
required.
 Importance of support for mother cannot be overestimated.
 Leading twin should be delivered as for a singleton, but with care to
ensure adequate monitoring of the second throughout.

26. Cont..
After delivery of first baby, the lie of the second twin should be checked
and gently ‘stabilized’ by abdominal palpation while a VE is performed to
assess the station of the presenting part.
 It may be helpful to have an ultrasound scanner available in case of
concerns about malpresentation of the second twin.
Once the presenting part enters the pelvis the membranes can be broken
and the second twin is usually delivered within 20min of the first.

27. Cont..
Judicious use of oxytocin may help if the contractions diminish after
delivery of the first twin.
 If fetal distress occurs in the second twin, delivery may be expedited with
either forceps or ventouse.
If this is inappropriate, the choice is between CS and breech extraction
(often after internal podalic version). Breech extraction involves gentle and
continuous traction on one or both feet, and must only be performed by
an experienced obstetrician.

28. Cont..
It is never used to deliver singleton breeches.
 As there is an increased risk of uterine atony, syntometrine and
prophylactic oxytocin infusion is recommended.

29. Thank you.