Multiple pregnancy

Question 1

Incidence of multiple pregnancy?

Answer 1

1 in 65 live births (increase over time due to fertility treatments)

Question 2

What are

a) DCDA twins?
b) MCDA twins?
c) MCMA twins?
d) Conjoined twins?

Answer 2

a) dichorionic diamniotic twins - most common, non-identical, usually dizygotic from 2 eggs and 2 sperm, often related to IVF
b) monochorionic diamniotic twins - two separate sacs; identical and monozygotic (fertilized from one egg that then divides). shared placenta so inc risk of TTTS
c) monochorionic monoamniotic twins - 1 sac (rare), high risk of cord entanglement and foetal loss; identical, monzygotic, shared placenta = risk of TTTS
d) very rare, resulting from late/incomplete division of monozygotic pregnancy

Question 3

What are predisposing factors for twins?

Answer 3

Previous twins
FHx twins (dizygotic only)
Increased maternal age
Induced ovulation/IVF
Racial origin (1 in 23 for Nigerian Yoruba women, 1 in 150 Japanese)

Question 4

What are the common presenting features for multiple pregnancy?

Answer 4

In early pregnancy, uterus large for dates
Hyperemesis
Polyhydramnios

Question 5

What signs may be elucidated?

Answer 5

> 2 poles felt
Multiplicity of foetal parts felt
2 foetal hearts heard
USS confirms diagnosis (11-14w distinguishes DCDA from MCDA/MCMA)

Question 6

What sign is seen on USS in DCDA twins?

Answer 6

Lambda sign

Question 7

What complications may occur in multiple pregnancies?

Answer 7

Polyhydramnios
Pre-eclampsia (10% singleton pregnancies; 30% in twin pregnancies)
Anaemia (inc iron and folate requirement)
APH incidence rises (abruption and p.praevia)
Gestational diabetes
Operative delivery
Congenital malformation (amniocentesis more risky in multiple pregnancy)
Stillbirth (MCMA>MCDA>DCDA)

Question 8

What are the foetal complications of multiple pregnancies?

Answer 8

Raised perinatal mortality
Prematurity
FGR
TTTS - placental vascular anastomosis in monochorionic pregnancies (treatment with ablation by laser coagulation in utero)
Rarely, foetus papyraceous (foetal death in utero, shrinking and mummification) may be delivered prematurely

Question 9

What can be performed if one foetus has congenital abnormalities?

Answer 9

Selective foeticide (with intracardiac KCl) best used before 20w

Question 10

What complications may present in labour?

Answer 10

PPH
Malpresentation (Ce/Ce and Ce/Br each have incidence of 40%)
Vasa praevia rupture
Cord prolapse
Placental abruption
Cord entanglement (esp monoamniotic)

Question 11

What is the standard management of multiple pregnancy?

Answer 11

USS at 11 and 13w for viability, chorionicity, nuchal translucency, malformation
Monthly monitoring from 20w (2w if monochorionic: membrane folding may suggest TTTS) and name twins left and right
Refer to tertiary centre if discordant growth (>25%, suggests TTS)
Discuss delivery planning
Postnatal support groups

Question 12

What can be done in twin pregnancies with maternal anaemia?

Answer 12

FBC taken at booking, 20w, 28w, 34w

Treat if Hb <11.5 at any stage with ferrous sulphate 200mg PO BD

Question 13

How can congenital malformation be managed in twin pregnancy?

Answer 13

Folic acid 5mg PO OD throughout pregnancy
Screen for chromosomal abnormalities (e.g. nuchal translucency for Down’s); second trimester screening may be performed in twins but not in triplets
Anomaly scan should be performed at 18-20+6as in singletons and extended cardiac views performed

Question 14

How can HNT/pre-eclampsia be managed in twin pregnancy?

Answer 14

Offer aspirin to any women with any other risk factor for HNT to reduce risk
BP and urinalysis should be performed at every visit

Question 15

How often should routine growth scans be performed in multiple pregnancy?

Answer 15

DCDA - every 4w from 24w (more frequent if concerns_
MCDA - every 2w from 16w (can be decreased after 26w when TTTS risk has passed)
Each twin should be annotated on first scan (e.g. twin 1 maternal right, twin 2 maternal left) to ensure growth assessed correctly

Question 16

When should twins be delivered?

Answer 16

DCDA - elective delivery 37-38w
MCDA - elective delivery 36-37w
MCMA - elective CS 32w

Question 17

What mode of birth should be used for twin pregnancies?

Answer 17

Uncomplicated twins (DCDA/MCDA) at term where twin 1 cephalic, vaginal birth offered (CS does not increase/decrease risk vs vaginal)
Increased risk of morbidity of second twin at delivery (10% risk of CS even after successful vaginal birth of first twin)
If first twin not cephalic - elective CS offered and administration of corticosteroids to mother (for prevention of RDS) is recommended

Question 18

What problems are associated with multiple pregnancies from IVF?

Answer 18

Multiple birth (monozygotic)
Older mother effects
-Pre-eclampsia and pregnancy-induced HNT (PIH)
-CS delivery
-Diabetes in mother 
Donor egg problems (esp PIH)
Genetic defects (esp Beckwith-Wiedermann syndrome)
Low birthweight
-Prematurity
-FGR
Vasa praevia
Prematurity (twice as common as natural conceptions)
Perinatal mortality
Abnormality rates increased

Question 19

What is TTTS?

Answer 19

Twin-twin transfusion syndrome is caused by abnormal vessels through the shared placenta resulting in blood flowing predominantly form one baby to another

One baby becomes donor and is malnourished; other becomes engorged with excess blood (can develop heart failure)

Question 20

Are twins always genetically identical?

Answer 20

The majority of twins are dizygotic)fertilised by two separate sperm) so are not identical; the remaining third however are monozygotic, from mitotic division of a single zygote, so share some genetic characteristics

Question 21

What maternal risks are particularly common in pregnancy?

Answer 21

Gestational diabetes
Pre-eclampsia
Anaemia

Question 22

What are the foetal antenatal complications for all multiple pregnancies?

Answer 22

Mortality and morbidity (+ congenital abnormalities)
Miscarriage
Preterm labour
IUGR

Question 23

What are the foetal antenatal complications for monochorinicity?

Answer 23

TTTS
Twin anaemia polycythaemia sequence (TAPS): marked Hb differences between twins without liquor volume abnormalities of TTTS; can follow incomplete laser ablation for TTTS
Twin reversed arterial perfusion (TRAP): rare
IUGR
Co-twin death (death of one MC twin causes acute transfusion from other twin due to hypotension of deceased twin; other twin becomes hypovolaemic and dies - not problem in DCDA as no shared blood supply)

Question 24

If the twins are dizygotic, what are the genders likely to be?

Answer 24

DZ twins are always of different genders

Question 25

How is TTTS diagnosed?

Answer 25

Discordant liquor volumes
Recipient twin larger, polyhydramnios, fluid overload, heart failure
Donor twin smaller, oligohydramnios

Question 26

How is TTTS managed?

Answer 26

USS surveillance from 12w

Laser ablation if TTTS diagnosed