This document discusses selective intrauterine growth restriction (sIUGR) in both monochorionic and dichorionic twin pregnancies. It defines sIUGR and provides incidence rates. It describes the different pathophysiologies of sIUGR in monochorionic versus dichorionic twins. For monochorionic twins, sIUGR is classified into three types based on umbilical artery Doppler findings. Management strategies are discussed, including expectant management, cord occlusion, and laser surgery to separate placentas. Outcomes are generally worse for monochorionic twins with sIUGR. The challenges of managing dichorionic twins with sIUGR are also summarized.

1. COMPLICATED BY SELECTIVE
GROWTH
RESTRICTION
DR NAHLA WAER
LECTURER OB&GYN
ASWAN UNIVERSITY

3. DEFINITION
 A variety of criteria for diagnosing sIUGR
have been used :
 Significant intrauterine fetal size discordance
(difference in estimated fetal weight [EFW] of
greater than 20%)
 or may be defined as one twin falling
below the 10th centile in EFW or actual
birthweight

4. INCIDENCE
 sIUGR appears to occur at a similar rate in both
monochorionic and dichorionic pregnancies at11–
12%
 Neurological complications are more common in
monochorionic pregnancies affected by sIUGR
than dichorionic pregnancies

5. PATHOPHYSIOLOGY
pathophysiology of sIUGR in dichorionic pregnancies
is more commonly primary placental insufficiency
rather than uneven placental share as it is in
monochorionic pregnancies Unequal placental
sharing is the underlying cause of most sIUGR in
monochorionic pregnancies,but unequally shared
placentas have also been found that have more

7. SELECTIVE
INTRAUTERINE GROWTH RESTRICTION IN
DICHORIONIC TWIN PREGNANCIES
associated with placental insufficiency as it is
in singleton pregnancies,
abnormal umbilical artery or ductus venosus
Doppler are correlated with poor outcomes
more strongly associated with preeclampsia
than is sIUGR in monochorionic pregnancies

8.  unequal placental sharing is the usual cause of
sIUGR in monochorionic pregnancies, but the
clinical outcome is deter-mined by the number

10. CLASSIFICATION OF SELECTIVE
INTRAUTERINE GROWTH RESTRICTION IN
MONOCHORIONIC TWIN PREGNANCIES
The presence or absence of umbilical artery Doppler end-diastolic
flow in the affected twin at the time of diagnosis forms the basis
of the classification system proposed by Gratacos et al. (outlined
in Table 1 and Fig. 1).

11. CLASSIFICATION OF SELECTIVE
INTRAUTERINE GROWTH RESTRICTION IN
MONOCHORIONIC TWIN PREGNANCIES

12. CLASSIFICATION OF SELECTIVE FETAL GROWTH RESTRICTION IN
MONOCHORIONIC TWIN PREGNANCY. IN TYPE I, THE UMBILICAL ARTERY
DOPPLER WAVEFORM HAS POSITIVE END-DIASTOLIC FLOW, WHEREAS IN TYPE
II THERE IS ABSENT OR REVERSED END-DIASTOLIC FLOW. IN TYPE III,
THERE IS A CYCLICAL/INTERMITTENT PATTERN OF ABSENT OR REVERSED
END-DIASTOLIC FLOW

13. TYPE I
. Placental anastomotic patterns in type I pregnancies are similar to
uncomplicated monochorionic pregnancies, resulting in a fair
number of anastomoses and bidirectional fetal flow interchange.
Such interchange favours blood from the larger twin working in a
compensatory manner since, even if marginally, it is better
oxygenated, and this attenuates the effects of placental
insufficiency in the smaller fetus.

14. TYPE II
Type II pattern is characterized by persistently AREDF in the UA. sIUGR
type II pregnancies show a distribution of placental anastomoses quite
similar to uncomplicated MC twins, but with a more severe placental
discordance. Fetal territory of the IUGR twin is usually extremely small in
type II pregnancies. illustrating how inter-twin blood transfusion attenuates
the severity of growth restriction. Thus, placental insufficiency in type II is far
more severe than in type I and cannot be fully compensated by inter-twin
transfusion.

15. TYPE III
Type III sIUGR is defined by the presence of iAREDF in the UA Doppler
of the IUGR twin. The observation of this sign indicates the presence of a
large placental AA anastomosis, which facilitates transmission of the
systolic waveforms of one twin into the umbilical cord of the other one.
In most cases, the compensating effect of the large AA allows survival of the
IUGR fetus until advanced stages of pregnancy, without showing clear signs
of hypoxic deterioration. However,some cases are associated with a
significant increase in the risk of unexpected IUFD of the IUGR fetus and of
brain injury in the normally grown twin which explained by the high risk of
acute feto-fetal hemorrhagic accidents through the large AA vessel

16. PULSED DOPPLER
INSONATION OF THE
UMBILICAL ARTERY OF
THE SMALL TWIN IN A
MONOCHORIONIC
PREGNANCY WITH
SELECTIVE INTRAUTERINE
GROWTH RESTRICTION
TYPE III. THE
PHOTOGRAPH
REPRESENTS THE MOST
TYPICALLY OBSERVED
IMAGE, WITH A CYCLICAL
PATTERN OF POSITIVE,
ABSENT AND REVERSED
END-DIASTOLIC FLOW.

17. PULSED DOPPLER
INSONATION OF A
LARGE
PLACENTAL
ARTERIO-
ARTERIAL
ANASTOMOSIS,
SHOWING THE
CHARACTERISTIC
BIDIRECTIONAL
PERIODIC
PATTERN
RESULTING FROM
THE COLLISION
OF TWO
OPPOSITE
SYSTOLIC
WAVEFORMS

19. Although the incidence of sIUGR is similar between monochorionic
and dichorionic pregnancies, unexpected IUFD is more
common and serious neurological injury is more common
in monochorionic pregnancies affected by sIUGR, even if both
twins are live born.
The overall incidence of neurological injury is reported to be
between 0 and 33% .
Demise of one twin is associated with a 15% risk of death and 25%
risk of neurodevelopmental impairment in the cotwin due to the
acute fetofetal transfusion that may occur at the time of IUFD of
the first twin .
This makes the ability to predict the deterioration and IUFD critical
in the management of monochorionic sIUGR, particularly as most
of the available interventions also carry substantial risks to one or

20. presents unique difficulties as the needs of
one fetus must be weighed against an
other
and the progression of disease is often not
directly comparable with growth restriction

21. SELECTIVE
INTRAUTERINE GROWTH RESTRICTION IN
DICHORIONIC TWIN PREGNANCIES

22.  The principal dilemma in the management of dichorionic
pregnancies affected by sIUGR comes when the IUGR twin
is severely compromised at an -------------early
gestation.
 At this time, particularly before 28 weeks, iatrogenic
preterm delivery of the other-wise healthy appropriate for
gestational age (AGA) twin subjects this baby to the
substantial risks of prematurity
SELECTIVE
INTRAUTERINE GROWTH RESTRICTION IN
DICHORIONIC TWIN PREGNANCIES

23.  Expectant management, however, carries the risk of
intrauterine fetal demise (IUFD) of the IUGR twin.
 The main risk to the AGA twin is that the demise of the
cotwin may lead to preterm delivery.
 There is a 54% risk of preterm delivery after single IUFD
with a 3% risk of IUFD and 2% risk of
neurodevelopmental damage after the intrauterine
demise of one dichorionic twin
(Hillman SC et al)
SELECTIVE
INTRAUTERINE GROWTH RESTRICTION IN
DICHORIONIC TWIN PREGNANCIES

24. S.INTRAUTERINE GROWTH RESTRICTION IN
DICHORIONIC TWIN PREGNANCIES
There is a limited role for selective reduction in
dichorionic twin pregnancies affected by sIUGR. For
example, sIUGR associated with severe early-onset
preeclampsia has been treated with selective termination
of the growth-restricted twin, allowing the
pregnancy to continue successfully to term
.(Audibert F et al)

25. RFA. OF UMBLICAL
CORD

26. MONOCHORIONIC PREGNANCIES
 The key to defining the clinical course of sIUGR in
monochorionic twin pregnancies is in
understanding the impact of the monochorionic
placental vasculature and interdependent fetal
circulations on the underlying disorder of placental
insufficiency.
The aim is to prolong pregnancy to at least viability and to achieve
appropriate gestation for delivery (32–34 weeks),but to avoid the
complication of single fetal death and the consequences for the
surviving fetus.

27. The management of sIUGR is guided
by classifying the pregnancy according
to the umbilical artery Doppler and
targeting interventions at the highest
risk cases in accordance with the
parents’ wishes
MANAGEMENT OF SELECTIVE
INTRAUTERINE GROWTH RESTRICTION
MONOCHORIONIC PREGNANCIES

28. MANAGEMENT OF SELECTIVE
INTRAUTERINE GROWTH RESTRICTION
MONOCHORIONIC PREGNANCIES
Type I sIUGR carries an excellent prognosis,so
expectant management is seem to be
reasonable, regular ultrasound surveillance to rule
out progression to type II is required, elective delivery at
34 - 36 weeks is usually possible.
(Ishii K et al)

29. Type II and III pregnancies have a poorer
prognosis and are more likely to require intervention.
between 70 and 90% of cases can be expected to
deteriorate , and intact survival is reported at 37% .
The umbilical artery Doppler flow is not a useful
predictor of the speed of deterioration and IUFD but
other ultrasound parameters may be of use, in particular
changes in the ductus venosus Doppler and severe
oligohydramnios . Severe oligohydramnios was observed
MANAGEMENT OF SELECTIVE
INTRAUTERINE GROWTH RESTRICTION
MONOCHORIONIC PREGNANCIES

30. Three management options are available for type II and III
early-onset sIUGR in a monochorionic twin pregnancy:
1. Careful expectant management with an effort to maximize outcome
for both twins
2. Cord occlusion of the IUGR twin( bipolar or radiofrequency
ablation)
thus sacrificing the IUGR fetus to protect the larger twin from injury as
a result of acute intertwin transfusion associated with smaller co-twin
demise
3. Laser photocoagulation to physically separate the shared fetal
circulations to help protect the larger co-twin from injury or death
MANAGEMENT OF SELECTIVE
INTRAUTERINE GROWTH RESTRICTION
MONOCHORIONIC PREGNANCIES

31. SLPCVSelective laser photocoagulation of connecting vessels (SLPCV) of
placental vessels is an established treatment for TTTS, and there is
understandable interest in the benefit of using this technique in the
management of sIUGR in monochorionic pregnancies.
There are a number of theoretical advantages including achieving
separation of the fetal circulations and protecting the AGA twin
without necessarily sacrificing the smaller twin.
Unlike in the management of TTTS, however, the anastomotic
connections are not the root cause of the growth restriction and in
fact may be of net benefit to the smaller twin.
Removing from the smaller twin the compensation afforded by the
AGA twin circulation may only hasten the IUFD of the smaller twin
while protecting the AGA twin from the effects of that event.

34.  At each scan from 20 weeks of gestation (at 2-weekly interval s)
onwards, calculate EFW discordance using two or more biometric
parameters.
 Calculate percentage EFW discordance using the following formula:
([larger twin EFW – smaller twin EFW]/larger twin EFW) x 100.
 Liquor volumes as DVP should be measured and recorded (to
differentiate from TTTS). [New 2016]C
 An EFW discordance of more than 20% is associated with an increase in
perinatal risk.
 Such pregnancies should be referred for assessment and management
in fetal medicine units with recognised relevant expertise. [New 2016]B
Screening for sGR

35. THE MANAGEMENT OF SGR
 sGR in monochorionic twins requires evaluation in a fetal medicine centre with
expertise in the management of such pregnancies. [New 2016]
 In cases of early-onset sGR in association with poor fetal growth velocity and
abnormal umbilical artery Doppler assessments, selective reduction may be
considered an option. [New 2016]C
 In sGR, surveillance of fetal growth should be undertaken at least every 2 weeks with
fetal Doppler assessment (by umbilical artery and middle cerebral artery pulsatility
index, and peak systolic velocity). If umbilical artery Doppler velocities are abnormal,
the Doppler assessments should be undertaken in line with national guidance,
measuring ductus venosus waveforms. [New 2016]

36.  Clinicians should be aware that there is a longer
‘latency period’ between diagnosis and delivery in
monochorionic twins complicated by sGR compared
with growth restriction in dichorionic twin pregnancy
or singleton pregnancy. [New 2016]D
 Abnormal ductus venosus Doppler waveforms
(reversed flow during atrial contraction) or
computerised cardio tocography short-term variation
should trigger consideration of delivery.[New 2016
THE MANAGEMENT OF SGR

37. THE MANAGEMENT OF SGR
In type I sGR, planned delivery should be considered by 34–36 weeks of gestation
if there is satisfactory fetal growth velocity and normal umbilical artery Doppler
waveforms.
In type II and III sGR, delivery should be planned by 32 weeks of gestation,
unless fetal growth velocity is significantly abnormal or there is worsening of the fetal
Doppler assessment.
It is important to prospectively inform parents that in sGR and TTTS (even after
apparently successful treatment) there can be acute transfusional events (which are
neither predictable nor preventable) and therefore, despite regular monitoring, there may
still be adverse perinatal outcomes.

38. CONCLUSION
Recent years have provided a greater understanding of
the pathophysiological basis of sIUGR, and early studies
have demonstrated the feasibility and potential lbenefits
of SLPCV for monochorionic sIUGR.A large-scale trial is
now necessary to provide a definitive guide to the management
of these complex pregnancies.

40. THANK YOU