3. Hari Dev
2008 MBBS

4. MULTIPLE PREGNANCY
• Presence of more than one fetus in the gravid
uterus
• 1% of all pregnancies
• Hellin’s Rule
– Twins : 1 in 80
– Triplets : 1 in 80 × 80
– Quadruplets : 1 in 80 × 80 × 80….
• Gemellology : Study of twins

5. • ZYGOSITY - Refers to the Type of Conception.
- only determined by DNA testing
• CHORIONICITY - Type of Placentation
- prenatally by ultrasound
- postnatally by examining
membranes.

6. 1. ZYGOSITY
Dizygotic Twins
Monozygotic Twins

7. 1.DIZYGOTIC TWINS/ BINOVULAR
75%
Fertilisation of 2 ova by different spermatozoa.
Each twin has its own placenta, chorion , amnion.
Hence always dichorionic, diamniotic.
Factors affecting - ethnic group
- increasing maternal age
- increasing parity
- Family history of twinning
- ovulation induction with clomiphene citrate/
gonadotrophins resulting in multiple ovulation.

8. DIZYGOTIC TWINS/ BINOVULAR

9. 2.MONOZYGOTIC / BINOVULAR/ IDENTICAL
25%
Result from splitting of a single fertilized ovum
Always same sex and look alike. [ IDENTICAL ]
Rate of monozygotic twinning is relatively constant , not affected
by any factors.
True etiology unknown.
Type of placentation is determined by the time of splitting

10. MONOZYGOTIC TWINS

11. MONOZYGOTIC / BINOVULAR/ IDENTICAL

12. 2.CHORIONICITY
• Type of Placentation
• Postnatally- Examination of Membranes
• Prenatally- By Ultrasound
• Ideal time for assesment is before 14 weeks

13. Which is more important –
zygosity or chorionicity??

14. CHORIONICITY………Why????
• Dichorionic twins can be either
mono/dizygotic.
• Dichorionic twins develop as two distinct
organs. – so no risk.

15. CHORIONICITY………Why????
• Monochorionic twins have increased vascular
anastomoses between the two circulation
– so high risk!!

16. Ultrasound Determination of Chorionicity
• Number of sacs. [ before 10 weeks ]
 2 sacs – dichorionic
 Single sac - monochorionic
• Placenta
• Sex
• Intertwin membrane
 thicker and more echogenic in dichorionic
.

17. • Twin peak / Lambda sign
- characteristic of dichorionic pregnancies
- chorionic tissue between 2 layers of
intertwin membrane at the placental origin
• T Sign – in monochorionic , no chorionic tissue
• If no membrane is seen in between –
monochorionic monoaniotic

19. Ultrasound differentiation of chorionicity
Criterion Monochorionic Dichorionic
Placenta Single Double
Fetal Sex -------- Discordance
Membrane <2 mm >2 mm
No: of layers in 2 layers 4 layers
membrane
Twin peak sign Absent Present

20. Maternal Complications
Antepartum Intrapartum
1.Hyperemesis 1.Dysfunctional labour
2.Hydramnios 2.Malpresentation
3.Pre-eclampsia 3.Operative delivery
4.Pressure symptoms 4.Postpartum
hemorrhage
5.Anaemia 5.Retained Placenta
6.Antepartum 6.Premature separation
hemorrhage of placenta

21. Maternal Complications - Antepartum
Hyperemesis – increased β- hCG
Hydramnios – monoamniotic pregnancies, Twin
transfusion syndrome, major cause of prematurity
Pre- eclampsia – 3 times commoner compared to
singleton
Pressure symptoms
Anaemia – increased plasma volume expansion ,
fetoplacental demand for iron increased.
APH – Placenta praevia , Abruptio placenta.

22. Fetal Complications
Antepartum Intrapartum
1.Prematurity 1.PROM
2.IUGR 2.Cord Prolapse
3.Single fetal demise 3.Abruption in second
twin
4.Twin to Twin transfusion 4.Interlocking (rare)
syndrome
5.Vanishing Twin/abortion
6.Cong.anomalies
7.Conjoined twins

23. FETAL COMPLICATIONS
 Perinatal mortality: 6 times
 Morbidity: 2- 3 times
 Mono chorionic - morbidity/mortality twice as that of dichorionic.
- additional risk from TTS
 Monoamniotic twins - 50% mortality.
 Main cause of adverse outcome is
1. Prematurity
2. IUGR
 Cerebral palsy, neurodevelopmental impairment, lower IQ scores.
 Monochorionic twins: 1. TTTS
2 .Monoamniotic twinning
3. Conjoined twinning
4. Acardiac fetus

24. 1. Prematurity
• Single most important cause of perinatal
mortality and morbidity.
• Ensure delivery in a tertiary care centre.!!

25. 2. IUGR
Can affect one or both fetuses.
Monochorionic > Dichorionic.
UPTO 30-32 Weeks twins grow with same velocity , after
that reduction in abdominal circumference.
Poor growth – poor placentation , unequal placental
sharing, fetal anomalies.

26. 3. SINGLE FETAL DEMISE
Death of one twin
NEUROLOGICAL
DAMAGE
in surviving TWIN
Sudden acute shift
of blood from
surviving twin to
dead fetus

27. 3. SINGLE FETAL DEMISE
Monochorionic - 25% risk of twin death, 25% risk of
neurological damage in surviving twin.
• Dilemma exists whether to deliver early or not
• Terminated as soon as other twin is capable of extra uterine
survival
Dichorionic – no such risk
• Conservative management

28. 4.Monochorionic Monoamniotic twinning
Seen in less than 1% of all twin pregnancies
Late intrauterine death due to cord entanglement.
Best diagnosed in 1st trimester – absence of intervening membrane.
Colour doppler – cord entaglement
Fetal loss – 50-70%
Hence elective CS at 36 weeks.

30. 5. Twin – twin Transfusion Syndrome
[ TTS]
Occurs in monochorionic placentation due to
AV anastomoses with resultant flow in one
direction.

31. 5. Twin – twin Transfusion Syndrome
[ TTS]

32. Ultrasound in TTS – STUCK TWIN SIGN

33. • Management after delivery –
Exchange transfusion
• Chronic TTS – Serial amnio reduction –
- Reduces preterm labour
- Reduce hydrostatic pressure –
- improves circulation and urine production.
• Fetoscopic laser ablation of anastomoses

34. • Acute TTS can occur in 3rd trimester or in
labour – sudden death of one twin
• Overall mortality is 70%
• High incidence of CP and neurological
abnormalities in survivors.

35. 6. Vanishing Twin & Abortion
Incidence of abortion more in multiple pregnancy
Spontaneous cessation of cardiac activity in a previously
viable fetus of a multiple gestation. – VANISHING TWIN
When fetal death occur after the first trimester, results in
a thin parchment – like body called FETUS PAPYRACEOUS
Diagnosis made after delivery
No effect on mother or the viable fetus.

37. 7. Congenital Anomalies
STRUCTURAL MALFORMATIONS
• Unique to twins – conjoined twins , Acardiac fetus
• Non specific but common in twins – CHD , Anencephaly
• Postural deformities – Talipes & Congenital dislocation of
Hip
CHROMOSOMAL ANOMALIES
• Dizygotic – independent risk, but both will not be involved
• Monozygotic – same risk as that of singleton, both affected
• Down’s syndrome

38. Nuchal Translucency
Mid Trimester
Amniocentesis is
the gold standard

39. Management of Anomalies
Selective
DICHORIONIC If one fetus is
feticide using
PREGNANCY abnormal
KCl

41. Conjoined Twins
Always monozygotic
Incomplete division occuring after 13 days.
Very rare
Thoraco pagus, craniopagus, omphalopagus, pyopagus, ischiopagus..
Prenatal diagnosis important – for termination , for planning operation
Severe cases detected early – Termination
Surgical separation only in some cases – sharing of brain and heart – unsuccessful operation
Caesarean preferred

42. THORACOPAGUS CRANIOPAGUS ISCHIOPAGUS
OMPHALOPAGUS PYOPAGUS RACHYPAGUS

43. Acardiac Foetus
Very rare
Bizarre form of monochorionic twinning
One fetus is normal
The other twin is severely malformed – no heart , absent
development of upper part of body

44. MECHANISM
PUMP TWIN ACARDIAC TWIN

45. Twin Reversed Arterial Perfusion
Sequence [ TRAP]
•Pump twin – high output cardiac failure, hydrops,
poly hydramnios and death
•Overall perinatal mortality of pump twin is 50%

46. ACARDIAC TWIN PUMP TWIN

47. THANK YOU