The 2 for 1 special:
Not always a good
deal
The 2 for 1 special . . .
Johanne Delisle, r.t
CHU Sainte-Justine
Medical imaging department
Montreal, Quebec, Canada
Not always a good deal
The 2 for 1 special . . .
Refered patient, gestation period of 24 weeks:
? ? ? type of twin pregnancy ? ? ?
Polyhydramnios
The 2 for 1 special . . .
Oligohydramnios
The 2 for 1 special . . .
Hydrops
Stuck twin
„
1
Quiz question
The 2 for 1 special . . .
How many varieties of
twin pregnancies are
there?
2, 3, 4, 5, 6
The 2 for 1 special . . .
The 2 for 1 special . . .
6 Types
6 Types
1. DIZYGOTIC
dichorionic – diamniotic
(DI – DI)
2. MONOZYGOTIC
dichorionic – diamniotic
3. MONOZYGOTIC
monochorionic – diamniotic
5. Conjoined twins
(pathological division )
6. Acardius
(pathological division )
(DI – DI)
(MONO – DI)
4. MONOZYGOTIC
monochorionic – monoamniotic
(MONO – MONO)
The 2 for 1 special . . .
Conjoined twins
ƒ Incomplet and late division
ƒ Conjoined areas and shared
organs
The 2 for 1 special . . .
Acardius
ƒ Absence of heart
ƒ The « normal » twin provides
blood flow through placental
anastomoses
„
2
The 2 for 1 special . . .
Popular belief
Mortality – Morbidity
Non-identical or dizygotic
Identical or monozygotic
DZ
Dichorionic – Diamniotic
9%
MZ
Monochorionic – Diamniotic
MZ
:
26%
Monochorionic – Monoamniotic
MZ
:
50%
The 2 for 1 special . . .
→
→
→
2 ovules
66% of cases
familial history
→
→
→
1 ovule
33% of cases
« genetic mistake"
Dizygotic twins
The real scientific data . . .
DIchorionic
(2 placentas)
Always
DIamniotic
Dizygotic twins
DIchorionic
Dizygotic twins
DI - DI
DIZYGOTIC
DIamniotic
DI - DI
„
3
1.
Dizygotic twins
Dizygotic twins
DI - DI
DI - DI
Fetal genders ?
1.
Fetal genders ?
2. 2 placentas
1.
Dizygotic twins
Dizygotic twins
DI - DI
DI - DI
Fetal genders ?
2. 2 placentas
3. Thick membrane
Dizygotic twins
DI - DI
100 %
1. Different fetal genders
Quiz question
Could these twins be DI – DI?
2. 2 placentas
„
4
Dizygotic twins
Dizygotic twins
YES
2 fused placentas
2 fused placentas
Dizygotic twins
Dizygotic twins
DI - DI
DI - DI
2 placentas
100%
3. Thick membrane
> 2 mm
„ + 2 layers
„
single placenta
Dizygotic twins
DI - DI
3. Thick membrane
„
Twin Peak Sign
or
Lambda sign
reliable
Dizygotic twins
What is the optimal timing gestation to
recognize the DI – DI?
ƒ
8 weeks
ƒ 14 weeks
ƒ 18 weeks
ƒ 26 weeks
„
5
Dizygotic twins
Dizygotic twins
Dichorionic twins
8 weeks
Monochorionic twins
Late assessment
=
Twinning type
mistakes
Dizygotic twins
Quiz question
2 placentas
„ 1 thick membrane
„ 2 males
„
The first trimester is the most
reliable time to characterize the
type of twinning
Monozygotic twins
YES
Monozygotic twins
present as DI – DI
in 30% of cases
The parents ask you if the twins can be
«identical » ?
Monozygotic twins
MONOchorionic
(1 placenta)
MONOZYGOTIC
DIamniotic
MONO - DI
„
6
Monozygotic twins
Monozygotic twins
MZ Mono - Di
MZ Mono - Di
Monozygotic twins
MONO - DI
Monozygotic twins
MONO - DI
1. Same fetal gender (100%)
Monozygotic twins
MONO - DI
Monozygotic twins
MONO - DI
1. Same fetal gender (100%)
1. Same fetal gender (100%)
2. Single placenta
2. Single placenta
3. Thin membrane
(100%)
(100%)
„
7
Monozygotic twins
3. Thin membrane
Monozygotic twins
MONOchorionic
Monozygotic twins
Membrane
thin
thick
Monozygotic twins
MZ Mono - Mono
(single placenta)
MONOZYGOTIC
MONOamniotic
MONO - MONO
MZ twins
Monozygotic twins
MONO - MONO
Monozygotic
Mono - Mono
„
8
Monozygotic twins
Monozygotic twins
MONO - MONO
MONO - MONO
1. Same fetal gender (100%)
1. Same fetal gender (100%)
2. Single placenta
Monozygotic twins
MONO - MONO
(100%)
Monozygotic twins
3.
No membrane
1. Same fetal gender (100%)
2. Single placenta
3. No membrane
(100%)
Monozygotic twins
Monozygotic twins
Cords
Mono-Mono
Entanglement
Strangulation
„
9
The 2 for 1 special . . .
The 2 for 1 special . . .
Monochorionic
US follow-up for normal twin pregnancies:
Complication = Vascular anastomoses
„
„
Twin-to-twin transfusion syndrome (TTS)
Twin embolisation syndrome (TES)
Complications (I)
¾ Preterm labor
Premature rupture of membranes
- monochorionic > dichorionic
¾ Fetal malformations
- monochorionic > dichorionic
¾ Weight discrepancy (ratio > 0.93)
Amniotic fluid discrepancy
- monochorionic = dichorionic
Quiz question
What type of twins ? ? ?
ƒ
Dz DI-DI
ƒ
Mz
DI-DI
ƒ
Mz
MONO-DI
ƒ
Mz
MONO-MONO
ƒ
ƒ
ƒ
Early exam
Every 2 weeks from 18
24 weeks
Every 4 weeks (MZ-DZ)
Complications (II)
¾ Intrauterine demise
- monochorionic > dichorionic
¾ Twin to twin transfusion syndrome (TTS)
- monochorionic
¾ Twin embolisation syndrome (TES)
- monochorionic
¾ Cord entanglement
- monochorionic - monoamniotic
Quiz question
Type of twinning
DZ
DI-DI
„
10
Acknowledgements
Acknowledgements
Andree Grignon
M.D.
Suzanne Laframboise
Jocelyne Gagne
Laurent Garel
M.D.
„
11