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Flashcards in Multiple Pregnancy Deck (16):

How are twins categorised and how common are each type?

Monozygous division of a single zygote. (20%) 1 in 300 pregnancies.

Dizygous from two fertilised eggs. (80%) 1 in 89 pregnancies.


What is a major risk factor for multiple pregnancy?

In vitro fertilisation 2-3 x more likely

Or ovulation induction


What is important to establish in multiple pregnancy?

Whether monozygotic twins are Di or Mono chorionic (2 placentas or do they share one)

Whether monozygotic twins are Di or Mono amniotic (whether they have 2 separate amniotic scan or share one)

Different combos are:
-Dichorionic/diamniotic (2 separate placentas and amniotic sacs)

-Monochorionic/diamniotic (1 placenta and 2 amniotic sacs)

-Monochorionic/monoamniotic (1 placenta and 1 amniotic sac)

Last outcome is incomplete separation aka conjoined twins.

Note if they separate earlier then more likely to have 2 of everything.


What are the principles of antepartum management in multiple pregnancy?

Consultant led care

Early diagnosis:
Usually diagnosed at first USS, uterus may also be large for dates & may auscultate 2 fetal hearts

Determine chorionicity:
On USS how widely spaced are the uterine sacs

Regular follow up:
Serial USS for growth
Screen for complications
Give low dose aspirin to prevent pre-eclampsia.
Iron and folic acid supplementation


If there is a female and a male twin seen on USS will the chorionicity be?

Different sex therefore non identical, must be dizygotic therefore must be dichorionic/diamniotic


What are the potential maternal complications of multiple pregnancy?

Hyperemesis gravidarum
Gestational diabetes
Pre-term labour
Post partum haemorrhage


What are the potential uteroplacental complications of multiple pregnancy?

Placenta previa
Preterm premature rupture of membranes



What are the potential fetal complications of multiple pregnancy?

IUGR (more common in monozygitic)

Fetal growth discordance (20% difference in estimated fetal weight between foetuses)

Congenital abnormalities (only increased risk in monzygotic twins)

Increased miscarriage rate

Increased perinatal mortality

Twin to twin transfusion (only in Momo twins)

Twin embolisation syndrome

Cord entanglement (quite common in mono twins)


How can multiple pregnancies be delivered?

Depends on fetal lie.

If both twins are cephalic vaginal delivery indicated.

If first twin is cephalic second twin breech, then vaginal delivery of first then ECV and second delivery.

If first twin is breech then C-section is necessary.

Other indications of c-section are:
-Fetal distress during labour (continuous CTG in multiple pregnancies)
-Antepartum complications
-Higher order multips
-Other indications for c-section


When do dichorionic and monochorionic twins usually deliver by?

37-38 weeks

34-37 weeks


What is the incidence of twins?

1.3% of births


What is twin to twin transfusion?

Results from an imbalance of blood flow from a donor twin to a recipient twin in monochorionic twins.

May initially present as polhydraminos/oligohydraminos sequence (one twin as poly other has oligo).

Twin to twin transfusion is a more severe form if this, after delivery the diagnosis is confirmed by there being a 20% difference in weight and 5g/dL difference in haematocrit. (clinically one large red baby, one small pale baby)

Prognosis is dependent on gestation and severity but perinatal mortality is high 40-80%.


How can twin to twin transfusion be managed?

If diagnosed intently can have uteroplacental laser surgery to ligate some of the vessels.

If postnatally resus: removal of fluid in one baby, blood transfusion in other baby.


What is the incidence of twin to twin transfusion?

15% in Monochorionic twins


What is stuck twin syndrome?

US diagnosis in which there is sever oligohydraminos of the affected foetus which appears vacuum packed in its membranes.

Has a very high perinatal mortality


What is twin reverse arterial flow (TRAP) sequence?

It is a condition in which there is retrograde flow from one twin up the umbilical aa to its co twin before returning to the placenta.

Causes severe congenital abnormalaties including acardia.