presentation on twin gestation

1. TWINPREGNANCY

2. INTRODUCTION
• 1% of all pregnancies
• Over 97% of all multiple pregnancies are twin
pregnancies (Joseph 1998).
• Associated with increased perinatal mortality & morbidity
• Results from ovulation & fertilization of > 1 oocyte OR
splitting of 1 embryonic mass to form 2 genetically
identical fetus
• Since 1970, the prevalence of multiple births has been
increasing because of more widespread use of ART.

3. INCIDENCE
Hellin’s law
Twin 1 : 80
Triplets 1 : 802
Quadruplets 1:803
Quniplets 1:804
Frequency of twins : highest – black race,
lowest – orientals
Increase with maternal age and parity
Increase with ART

4. TERMS
Zygosity refers to the type of conception
Two thirds of all twins are dizygotic.
Chorionicity denotes the type of
placentation.
*Chorionicity rather than zygosity
determines outcome.

5. TWINS
DIZYGOTIC
2/3
MONOZYGOTIC
1/3
Monochorionic monoamniotic <1%
Monochorionic diamniotic -75%
Dichorionic diamniotic -25%
Dichorionic
Diamniotic

7. DIZYGOTIC
• Fertilization of 2 separate ova

8. DIZYGOTIC
• incidence of dizygotic twins varieswith
–ethnic group - up to 5 times higher in
certain parts of Africa and half ashighin
parts ofAsia
–maternal age - 3 in 1000 births in women
younger than 20,14 in 1000 births in
women aged 35-40 y
–Parity - 2%after four pregnancies
–method of conception - 20%withovulation
induction.

9. MONOZYGOTIC
• Also known as identical twins.
• 1/3 of twin.
• Fertilization of single ovum
• Similar sex
• Identical in every way including HLA genes
• Not genetically determined
• Its prevalence 1/250

10. THE OUTCOME OF TWINNING PROCESS DEPENDS ON
WHEN THE DIVISION OCCUR
monochorionic
*Division after 13 days  Conjoined twin

12. ZYGOSITYAND CHORIONICITY
• Zygosity - determined by DNAfingerprinting.
– require an invasive procedure – amniocentesis,
chorionic villus sampling orcordocentesis
• Chorionicity - determined by USS(fetal gender,number of
placentas and characteristics of the membrane betweenthe
two amnioticsacs).
– Different-sex twins =dizygotic anddichorionic,
– but in 2/3 of twin pregnancies the fetuses same sexand
these may be either monozygotic ordizygotic.
– Twoseparate placentas=dichorionic
– but, iftwo placentas are adjacent to each other and
therefore difficult to distinguish betweendichorionic-
fused and monochorionic placentas.

13. ZYGOSITYAND CHORIONICITY
• Thebest way to determinechorionicity
 ultrasound examination at 10-14 weeksof
gestation
• Lambda sign-Dichorionic
• T-sign - Monochorionic

17. DIAGNOSIS OF MULTIPLE PREGNANCY
History : h/o IVF, taking ovulation inducing drugs
Symptoms
 Early pregnancy : excessive nausea, vomiting, Abnormal
bleeding
 Mid pregnancy : excessive weight gain, uterus larger than date
 Late pregnancy : pressure symptoms – dyspnea, dyspepsia
Signs :
 Anemia, edema, high BP, abnormal weight gain
 Uterus larger than date
 Multiple fetal poles felt
 2 distinct FH heard
Ix : confirm by Ultrasound
Detect 99% of multiple gestation before 26 weeks
Confirms fetal viability
Diagnose type
 Confirm fetal numbers.

18. Patientcare
• Ultrasound at 10–14 weeks: (a)
viability; (b) chorionicity; (c) NT
:
aneuploidy
• Structural anomaly scanat 20–22
weeks.
• Serial fetal growth scanse.g24,
28, 32 and then two- to four-
weekly.
• 34–36 weeks: discussion of mode
of delivery and intrapartumcare.
• Elective delivery at 37–38
completed weeks.Someby
40weeks
• Postnatal advice and support
(hospital- andcommunity-based)
to include breastfeeding and
contraceptive advice
Dichorionic twins Monochorionic twins
• Ultrasound at 10–14 weeks: (a)
viability; (b) chorionicity; (c) NT
:
aneuploidy/TTTS
• Ultrasound surveillance forTTTS
and discordant growth: at 16
weeksand then two-weekly.
• Structural anomaly scanat 20–22
weeks(including fetal ECHO).
• Fetal growth scansat two-weekly
intervals until delivery.
• 32–34 weeks: discussionof mode
of delivery and intrapartumcare.
• Elective delivery at 36–37
completed weeks(if
uncomplicated).
• Postnatal advice and support
(hospital- and community-based)
to include breastfeeding and
contraceptive advice.

19. At what age should genetic testing be offered to a
mother with dichorionic and monochorionic
twins?
• All women carrying twin pregnancies should be
referred for counselling to a centre for the
consideration of invasive testing at age 32.
• The counselling must be individualized and the
final decision must be taken by the parents
since the risk of amniocentesis is uncertain in
twin gestation.
―Thechance of a 32 year old woman who carries
twins of unknown zygosity having at least one child
with Down syndrome is equivalent to the risks of a
35 year old with a singleton pregnancy.‖

20. METHODS AVAILABLE FOR GENETIC
SCREENING IN TWIN PREGNANCIES
• Biochemical screening for aneuploidy is not
recommended in twins.
• Maternal serum alpha fetoprotein (MS-AFP) is
useful for detection of open neural tube and other
birth defects.
• Evidence is promising that nuchal translucency
(NT) screening is useful for identifying twin
pregnancies at high risk of aneuploidy.
• The fetal loss rates with invasive testing
(amniocentesis and chorionic villus sampling
(CVS)) in twins are unclear.
• Invasive testing should be offered to twins according
to the usual standard of care.

21. HOSPITAL BEDREST
• Randomized controlled trials and a meta-
analysis of hospital bedrest in twin
pregnancies have shown no reduction in
preterm birth or perinatal death.
• In uncomplicated twin pregnancies, hospital
rest may result in increased risk of very
preterm birth and maternal psychosocial
stress.
• In women with twin pregnancy at high risk
for preterm birth because of premature
cervical change prior to labour, there is no
evidence that hospital bedrest will reduce
the rate of preterm birth.

22. ACTIVITY RESTRICTION/WORK LEAVE
• Restriction of activity level and the
recommendation to stop work is commonly
prescribed for women with twin pregnancies
as a preterm birth prevention strategy.
• This prophylactic intervention has only been
studied in a few observational trials with
historical or geographic controls with
conflicting results.
There is insufficient evidence to support
prophylactic activity restriction or work
leave in multiple gestation.

23. CERVICAL CERCLAGE
Prophylactic cervical cerclage has not been
shown to be effective in preventing preterm
birth in twin pregnancy in observational or
controlled trials.
There is moderate evidence against
routine prophylactic cervical cerclage in
multiple gestation. However, cerclage
may be indicated for the treatment of
incompetent cervix or other specific
circumstances.

24. PROPHYLACTIC TOCOLYTIC THERAPY
Most randomized controlled trials have failed
to show any benefit of prophylactic oral or
intravenous tocolytic therapy in multiple
gestation.
There is moderate evidence against
prophylactic tocolysis in the
management of multiple gestation, but it
may be indicated on other grounds.

25. Is there a role for routine clinical cervical
assessment in
multiple gestation?
• Despite the lack of precision, clinical cervical
assessment appears to be safe and may be effective
in monitoring twin gestations, if transvaginal
ultrasound is not available or determined to be too
expensive.
• However, compared to transvaginal sonography,
digital examination is more subjective and less
reproducible.
There is good evidence that premature cervical
change by digital examination predicts preterm
birth in twins.
Since there are no well designed intervention trials
available,the role of sonographic clinical cervical

26. Is home uterine activity monitoring useful in
predicting
preterm birth in twin pregnancy?
Although home uterine activity monitoring may be
helpful in identifying women at increased risk of
preterm labour before advanced cervical dilation
occurs, this information has not resulted in
reduction in the incidence of preterm labour,
advanced cervical dilation at presentation or
preterm birth in well-controlled randomized
controlled trials.
*There is moderate evidence against home
uterine activity monitoring in multiple
gestation.

27. Does the measurement of fetal fibronectin predict
preterm birth in twin pregnancy?
Data from prospective longitudinal studies suggests that a
positive
fetal fibronectin test has a very high negative predictive
value for the prediction of preterm birth in asymptomatic
patients. The positive predictive value for preterm labour and
delivery before 37 weeks is 60 percent for patients in preterm
labour, 45 percent in asymptomatic high-risk women, and 30
percent in asymptomatic low-risk women.
There is good evidence that the presence of cervicovaginal
fetal fibronectin in twins predicts preterm birth. Without
well designed intervention trials available, there is no basis
for incorporating fetal fibronectin screening into routine
prenatal management of multiple gestation.

28. MORTALITY AND MORBIDITY
• Multifetal pregnancies are high-risk pregnancies.
• fetal mortality rate for twins is 4 x the fetal mortality rate
for single births.
• neonatal mortality rate for twins is more than 5 x greater
than the neonatal mortality rate for single births.
• A high prevalence of low birth weight infants, due to
prematurity and intrauterine growth retardation (IUGR)
and their associated complications, contribute to this
problem.

29. Complications of MultiplePregnancy
• preterm labor andbirth
• pregnancy-inducedhypertension/PE
– Women with multiplefetuses are more than three times aslikely to
develop high blood pressure ofpregnancy.
– Thiscondition often develops earlier and is more severethan
pregnancy with onebaby.
– It canalso increase the chanceofplacental abruption (early
detachment of theplacenta).
• anemia
– Anemia is more than twice ascommon in multiple pregnancies asina
single birth.
• birthdefects
– Multiple birth babies have about twice the risk of congenital (present
at birth) abnormalities including neural tube defects (such asspina
bifida), gastrointestinal, and heartabnormalities.

30. FETAL COMPLICATIONS

31. MATERNAL COMPLICATION

32. UNIQUE COMPLICATIONS
• Problems related to vascular
anastomosis between twins
• Single intrauterine demise
• Discordant twins
• Conjoined twins
• Cord entanglement

33. 1. VASCULAR ANASTOMOSIS
Present only in monochorionic twin placentas.
Nearly 100% of monochorionic twin placentas have vascular
anastomoses,but there are marked variations in the
number ,size, and direction.
2 patterns of vascular anastomosis
• twin-to-twin transfusionsyndrome (TTTS)
• acardiac twinning or twin reversed arterial perfusion (TRAPS)

34. Twin-to-twin transfusion syndrome
(TTTS)
• Features of TTTSare the result of hypoperfusion
of the donor twin and hyperperfusion of the
recipient twin.
• twin becomes hypovolemic and oliguric oranuric.
• Oligohydramnios develops in the amniotic sacof
the donortwin.
• Profound oligohydramnios can result in the stuck
twin phenomenon in which the twin appears in a
fixed position against the uterinewall.
• Ultrasonography may fail to visualize thefetal
bladder becauseof absenturine.

36. • Either twin candevelop hydropsfetalis.
– Thedonor twin canbecome hydropic becauseof
anemia and high-output heart failure.
– Therecipient twin canbecome hydropic because
of hypervolemia.
• Therecipient twin canalso develop
hypertension, hypertrophic
cardiomegaly, disseminated intravascular
coagulation, and hyperbilirubinemia after
birth.

37. Twin-to-twin transfusion syndrome
(TTTS)
• SevereTTTShasa60-100%fetal or neonatal
mortality rate.
• Mild-to-moderate TTTSis frequently
associated with prematuredelivery.
• Fetal demise of one twin is associated with
neurologic sequelae in 25%of survivingtwins.
• Themore premature the twins are atbirth,
the higher the incidence of postnatal
morbidity andmortality

38. QUINTERO STAGING

39. TWIN REVERSED ARTERIAL PERFUSION SEQUENCE
(TRAPS)
• 1:35,000pregnancies,1%ofmonochorionic
• Largearterio-arterial anastomosis
• Perinatalmortality inthepumptwinis 55%,dueto
polyhydramniosandhigh-outputcardiacfailure
• Anacardiactwinwhichreceivedits bloodsupplyvia alarge
arterio-arterialanastomosisfromanormal‘pumpco-twin~>resultin
absentorudimentarydevelopmentof theupperbody structures
• NotallpregnancieswithTRAPsequencerequire invasivetreatmentand
thisappearstobedependent on:
i) therelativesizeofthe‘acardiac’twintothepumptwinand
ii) thepresenceofanycardiovascularimpairmentinthe‘pump’twin
iii) Carefulmonitoringandultrasoundsurveillanceisrequired
.

41. SUGGESTED TREATMENT IN VASCULAR
ANASTOMOSIS
• Amniotic septostomy
• Laser ablation
• Selective fetocide
• Serial amnioreduction

42. Treatment for established TTTS:
The frequency of ultrasound surveillance of fetal
health in severe cases of TTTS will depend on the
severity and intervention strategy.
Therapeutic options: These include:
i) no intervention ( survival 0—30%),
ii) amnioreduction 64 percent ( survival 64% overall,
74%
of at least one twin),
iii)laser photocoagulation (55% overall survival—73%
of
at least one twin),
iv)amniotic septostomy, 83 percent survival (12 cases
only).

43. SERIAL AMNIOREDUCTION

44. LASER ABLATION

45. 2. SINGLE INTRAUTERINE DEMISE
• 2-6% of twins pregnancies
• Up to 25% in MC twin pregnancy
• Perinatal morbidity and mortality of the surviving co-
twin
19% perinatal death
24% having serious longterm sequelae
• Morbidity of surviving fetus depend on chorionicity
and consequences of prematurity

46. SINGLE FETALDEATH
• After the single fetal death in a monochorionic pregnancy, the
risk to the surviving twin of death or neurological abnormality
is of the order of 12% and 18%, respectively.
• Damage to MC twins after the death of a co-twin is now
thought to be caused by acute haemodynamic changes around
the time of death, with the survivor essentially haemorrhaging
part of its circulating volume into the circulation of the dying
twin.
• This may cause transient or persistent hypotension and low
perfusion,leading to the risk of ischaemic organ damage,
notably but not exclusively, to the brain
• Single fetal death in a monochorionic pregnancy should be
referred and assessed in a regional fetal medicine centre.

47. 3. DISCORDANT FETAL GROWTH
• Fetal growth differs slightly in twin gestations and twin specific charts
may be used to define the normal growth rate. Precision may also be
obtained by using sex and race specific charts.
• In clinical practice, however, these differences are small and singleton
growth curves may be used. Patterns of fetal growth are more important
than absolute measurements. Both must be interpreted in the light of
the clinical history, together with all the genetic and environmental
factors that may affect fetal growth.
The diagnosis of discordance has been based on the following:
• AC difference of 20 mm (sensitivity of 80%, specificity 85%, PPV= 62%)
• EFW based on bi-parietal diameter (BPD) and AC or AC and femur length
(FL) > 20 percent (sensitivity 25-55%)
Fetal weight difference = wt. of the larger - wt.of smaller
wt.of the larger twin
( >15-25% poor outcome )

48. • It has been shown that the risk of fetal death
begins to increase progressively when the
weight discordance exceeds 25%.
• Discordant fetal growth can be due to different
genetic growth potentials, structural anomaly of
one fetus, or an unfavourable placental
implantation.
• True discordance is an indicator for an increased
risk of IUGR, morbidity, and mortality for the
smaller twin.
• A risk for aneuploidy, anomaly or viral syndrome
affecting only one fetus must also be considered
when discordant growth is identified.

49. Management
US monitoring of growth within a twin pair = mainstay in
management .
The indication for delivery should take into consideration
of the fetal well-being, the gestational age and serial
growth velocity

50. 4. CONJOINED TWIN
Rare complication of monoamniotic twining, with
an incidence of around 1: 55 000 pregnancies.
Accurate prenatal diagnosis is possible in the first
trimester and allows better counseling of the
parents regarding the management options.
Types :
Anterior (thoracopagus)
Posterior (pygopagus)
Cephalic (craniopagus)
Caudal (ischiopagus)
van den Brand(1994) ;diagnosis of conjoined twins
can frequently be made at mid pregnancy using
USG - careful evaluation of the point of
connection and organs involved

53. 5. CORD ENTANGLEMENT
• Cord entanglement occurs in over 70% of MCMA twins and is
believed to be the major cause for sudden IUFD
• Ultrasound diagnosis of cord entanglement and close fetal
surveillance from 24 weeks onward, may help to improve
perinatal outcome.
• Because of the high perinatal mortality, prophylactic delivery by
caesarean section at 32 to 34 weeks is recommended.

54. PRESENT
A
TION
• 40%of twins present asvertex/vertex,
• 35%as vertex/non-vertex,
• remaining 25%of twins present with the
leading twin in anon-vertex presentationat
birth .
• Blickstein 1987; Grisaru 2000

55. DELIVERY
• If the first twin presents asbreech - -CSas
being safer for thebabies.
• Although many clinicians choose caesarean
section when the first twin presents asa
breech,because of concernabout
‘interlocking’, this complication isextremely
rare. Cohenet al.47 reported ‘interlocking’
occurring only once in 817 twinpregnancies
where the first twin wasbreech and the
second cephalic.

56. DELIVERY
• For twins presenting vertex/vertex, mostclinicians
recommend planned VB(ACOG2002; CDSR1996).
• However, planned C
Smay benefit twins in which thefirst
twin is presenting vertex for anumber ofreasons.
• Asmany as20%of vertex presenting secondtwins will
changepresentation spontaneously after the first twinis
delivered (Houlihan 1996).
• Asubstantial number of those presenting vertex/vertex will
present with serious acute intrapartum problems following
the delivery of the first twin (for example, conversion to
transverse lie, cord prolapse, prolonged interval to delivery
of the secondtwin), which may lead to emergency CS,
perinatal death, and neonatalmorbidity.

57. MANAGEMENT DURING LABOR
Basic Principles
The presence of 2 skilled obstetrics attendants for
labor and delivery
Anesthesiologist available
Neonatal care personnel sufficient for resuscitation of
the newborns
Portable US scanner
Reliable IV access
CTG with dual monitoring capacity

58. INTRAPARTUM MANAGEMENT OF TWIN
PREGNANCY
1st stage
Good intrapartum care : blood, IV access,
continuous FH monitoring, adequate analgesia
and LPC.
it is also preferable to have an USG in the delivery
suite to detect the FH, fetal lie and presentation
when needed.
Progress of labour should be closely monitored
with 2-4 hourly VE.
The criteria for diagnosing slow progress are the
same as in singletons.
In case of inefficient uterine contractions,
oxytocin augmentation can be used.

59. 2nd stage
 An experienced obstetrician must be present during the 2nd
stage of labour.
 Following delivery of the first twin, syntometrine must NOT be
given as it might facilitate the premature placental separation
before the delivery of the second twin.
 The cord of the first twin should be clamped and divided as
usual.
 After delivery of the 1st twin, the obstetrician should ascertain
the lie and presentation of the 2nd twin, using USG if required.
 Once a Cx presentation is confirmed, the decent of the fetal
head is expected with re-establishment of uterine contractions.
 Oxytocin infusion should be commenced if uterine contractions
have failed to resume.
 Fetal heart rate should be continuously monitored.
A twin-to-twin delivery interval of ≤ 30 minutes, after which
delivery should be expedited, since the risks of both acidosis
and second stage Caesarean section increase with the length of
this interval

60. If the second twin is in non-vertex presentation, the available
options include
 Assisted vaginal breech delivery or breech extraction,
 Internal podalic version following by breech extraction,
 ECV followed by vaginal cephalic delivery,
 Emergency LSCS

61. 3rd stage
•increased risks of primary PPH.
•delivery of the shoulder of the 2nd twin, active
management of the third stage should ensue.
•Oxytocin infusion in addition is advised.
•The placentas should be examined as a routine to
confirm the chorionicity and amnionicity.

62. Indications for Caesarean Section
Elective
First twin non-cephalic
Conjoined twin
Monoamniotic twin
Placenta previa
Previous LSCS
IUGR in dichorionic twin
Congenital abnormality
Emergency
Fetal distress
Cord prolapse of 1st twin
Non progress of labor
Collision of both twins
2nd twin transverse after delivery of 1st twin

63. SPECIALIZED TWIN CLINICS/PREVENTION
PROGRAMMES
Multi-intervention preterm birth prevention
programmes for twin pregnancies have been
evaluated in several observational studies with
contemporary and/or historical controls. All studies
reviewed suggest reduction in preterm birth
rate, decreased perinatal mortality, and overall
improvement in perinatal outcome.
The evidence to support specialized clinics is of
insufficient quality to recommend that they be
part of routine clinical practice. Further
randomized controlled studies are needed to
validate the improved outcomes that have been
demonstrated in cohort studies.

64. THANKYOU