Multifetal pregnancy

1. MULTIFETAL
PREGNANCY
PRESENTED BY:
DR. NITIN WADHWANI
DR. D.Y. PATIL HOSPITAL KOLHAPUR

2. ZYGOCITY
DIZYGOCITY
(2/3RD)
MONOZYGOCITY
( 1/3RD)

5. DETERMINATION OF CHORIONICITY
▪ Determination of chorionicity is best
performed very early in gestation,
when the gestation sac size is small
and the number of distinct sacs can
be clearly established.
▪ The number of sacs will determine
the number of chorions

6. ▪ A single gestational sac containing two yolk sacs is a monochorionic
pregnancy, and amnionicity then needs to be determined.
▪ The number of yolk sacs within a sac was historically thought to
accurately predict the number of amnion that is, two yolk sacs in a single
gestational sac corresponds with monochorionic diamniotic twins while
one yolk sac with two embryos indicates monochorionic monoamniotic
twins.
▪ However, more recently there have been reports of two yolk sacs leading
to two embryos within a single amnion, as well as a single yolk sac
leading to two embryos and two separate amniotic sacs.

10. TWIN PEAK SIGN or LAMDA SIGN

11. T SIGN

14. NAMING OF FETUS
▪ Determination is made on the first ultrasound in
the second trimester or in the late first trimester
at the time of nuchal translucency measurement.
▪ Fetus whose anatomic part is presenting (i.e., is
closest to the cervix) is termed fetus 1 (or A).
▪ The non presenting fetus is labeled twin 2 (or B).
▪ In larger-order multiples, the location in the
uterus is used as an identifying characteristic—
triplet 2 is upper right, triplet 3 is upper left, or
vice versa.
▪ There is no standard method of labeling higher-
order births beyond the presenter as number 1

15. AMNIOTIC FLUID ASSESSMENT
▪ Assessment of the amniotic fluid volume is
performed for each fetus individually. Fluid
volume is assessed either subjectively or
using the deepest vertical pocket.
▪ Occasionally, separation of the intertwin
membrane can be appreciated, with
amniotic fluid tracking between the
membranes. This appearance has not been
shown to be associated with an adverse
outcome.

16. UMBILICAL CORD ASSESSMENT
▪ The umbilical cord of each fetus should be evaluated for the
presence of three vessels, as both monochorionic and
dichorionic pregnancies have a higher incidence of single
umbilical artery than do singletons.
▪ The abnormal cord insertions include both marginal (11% of
twins) and velamentous (6%)

20. LOSS OF A TWIN
▪ Single intrauterine fetal death (IUFD) occurs in approximately
4% to 7% of twin pregnancies.
▪ After 22 weeks was twice as high for monochorionic diamniotic
as compared to dichorionic twins.
▪ After loss of one twin, the surviving twin is at increased risk for
adverse outcome, and the risk is again associated with
chorionicity, as a result of the vascular anastomoses in a shared
placenta.

22. DICHORIONIC MONOCHORIONIC
• No significant risk
in surviving fetus
• Pre term delivery
• Risk of severe cerebral
injury ( in 25-34%)

23. First fetus expires, there is a sudden
drop in vascular resistance across
the placental anastomoses
Blood is shunted away from the
survivor
Subsequent anemia, hypotension,
and hypoperfusion of vital organs

24. COMPLICATIONS OF MONOCHORIONICITY
▪ Abnormal growth, prematurity, and intrauterine demise seen in
monochorionic gestations are all related to the single placental
mass that is shared between the two fetuses.
▪ The majority of monochorionic placentas have vascular
connections that cross back and forth between the two fetal-
placental circulations, allowing minute amounts of blood
exchange between twins.

25. ▪ The anastomoses can be superficial or
deep, and there are three distinct types:
– arterial/arterial (AA)
– arterial venous (AV)
– venous venous (VV)

26. Twin-Twin Transfusion Syndrome
Twin Anaemia Polycythaemia Sequence
Twin Reversed Arterial Perfusion Sequence

27. TWIN-TWIN TRANSFUSION SYNDROME
▪ 10-23% of monochorionic pregnancies
▪ It is defined by oligohydramnios (deepest vertical pocket < 2
cm) with a small or empty bladder in the donor and
polyhydramnios (deepest vertical pocket >8 cm) with a
distended bladder in the recipient in a monochorionic pregnancy
▪ Syndrome is usually first identified between 16 and 26 weeks of
gestation.

31. Video link

33. TWIN ANEMIA POLYCYTHEMIA
SEQUENCE ( TAPS)
▪ TAPS occurs when there is sufficient
unequal passage of red cells via the
placental anastomoses such that one twin
becomes anemic (the donor) and one
becomes polycythemic (the recipient).
▪ Seen in 5% of monochorionic twins.

34. The transfusion occurs extremely slowly via tiny
unidirectional AV anastomoses, over a long period of time

35. The diagnosis of TAPS is made
prenatally with Doppler interrogation of
the middle cerebral artery in each fetus
The anemic fetus will demonstrate
elevated peak systolic velocity in the
middle cerebral artery (>1.5 multiples
of the median), while the polycythemic
fetus demonstrates decreased
velocities (<1.0 multiples of the
median)

37. TWIN REVERSED ARTERIAL PERFUSION
SEQUENCE (TRAPS)
▪ Occurs when one twin has an absent or severely malfunctioning
heart and there is a large unbalanced AA anastomosis within a
monochorionic placenta.

38. Blood flow is directed from the umbilical
artery of one twin (pump twin) through
the placenta and into the umbilical artery
in the second twin..(reversal)
Flow is then directed inferiorly down the
iliac arteries to the lower extremities of
the second fetus and then out of the
umbilical vein back to the placenta.
VV anastomoses allow that blood to then
return to the pump twin

40. Video link

42. MONOAMNIOTIC TWINS
▪ Both fetuses are located within a single
amnion and therefore a single chorion
▪ Monoamniotic twins should be suspected
when no intertwin membrane is identified by
10 to 12 weeks’ gestational age and can be
confirmed at any age when the umbilical
cords are seen to twist together or become
entangled

43. Monochorionic Monoamniotic Twins, 12 Weeks’ Gestational Age

44. CONJOINED TWINS
▪ Rare type of monoamniotic twins that occur with
late division of the embryo (>14 days)
▪ The twins can be conjoined at any skin site and
are diagnosed by demonstrating contiguous skin
covering between two fetuses

46. ▪ Conjoined twins can be diagnosed in the late first trimester
however, a detailed survey will be required by 18 to 20 weeks’
gestation for the most accurate evaluation of the degree of
visceral and vascular sharing
▪ The umbilical cord may also be fused, with more than three
vessels seen within a single cord.

47. Monochorionic Monoamniotic Conjoined Twins, 35 Weeks’ Gestational Age.