Multiple Pregnancy September 2021

Review of Multiple pregnancy

Some updated contents are included

1. Multiple Pregnancy

2. 2

3. Introduction
•Twin births account for
–3 percent of live births
–97 percent of multiple births
Zygosity
–fertilization of 2 ova
–is influencedremarkably by
•race, heredity, maternal age, parity, and, especially,
fertility treatment
–75% -same sex:
•Both –Males (45%), Females (30%)
–They bear only the resemblance of brothers
or sisters and may or may not have the same
blood type
–Significant differences usually can be identified
over time
3
–single fertilized ovum
–constant worldwide = I in 250
–independentof race, heredity, age, parity
•One exception is that rates of zygotic splitting
are increased following ART
–always of the same sex
–Monozygotic triplets
•repeated twinning (supertwinning) of a single
ovum
–Discordant if
•Postzygotic genetic mutations
•same genetic disease but with marked variability
in expression
•Due to this dizygotic twins of the same sex may
appear more nearly identical at birth than
monozygotic twins

4. 4
•Note: Triplets -may be
–Monozygotic –one ova
–Dizygotic –two ova
–Trizygotic –three ova
Mechanism of monozygotic twinning
•0 to 4 days ➔DCDA
–almost 1/3 of monozygotic twinning
–much lower rate of complications
•Division between 4 to 8 days ➔MCDA
–accounts for about 2/3 of monozygotic twinning
•Between 8 and 12 days➔MCMA
–is rare
–Complication →TTTS, sIUGR
•Division from days 13–15 ➔conjoined twins
–Commonest: parapagus
A traditional approximation of the incidence of
multiple pregnancies
Twins 1:80
Triplets 1:80
2
= 1:6400
Quadruplets (etc.) 1:80
3
= 1:512,000
Superfetation
•fertilization of 2 ova released in different
menstrual cycles
•impossible in humans
Superfecundation
•fertilization of 2 ova, released at
approximately the same time, by sperm
released at intercourse on 2 different
occasions
•Has happened -?? USA
•May -ART

5. Factors Affecting Twinning
•Maternal age
–DZ twinning –4X (15 -37 years
–Paradox -with advancing maternal age
•declining fertility
•but increasing twinning rates
•Heredity
•Nutrition
–Controversial: folic acid
supplementation
•Pituitary Gonadotropin
–The common factor linking race, age,
weight, and fertility to multifetal
gestation may be FSH levels
–Indeed, the paradox of declining
fertility but increasing twinning with
advancing maternal age can be
explained by an exaggerated pituitary
release of FSH in response to decreased
negative feedback from impending
ovarian failure
•Infertility Therapy
–Ovulation induction with FSH plus hCG
or clomiphene citrate
–in vitro fertilization (IVF): since
5

6. •Females predominate even more in twins from
late twinning events
•Two explanations have been offered
–First, beginning in utero and extending throughout
the life cycle, mortality rates are lower in females
•XX karyotype may confer a survival benefit
–Second, female zygotes have a greater tendency to
divide
Determining Zygosity
•Twins of opposite sex are almost always
dizygotic
–Rarely due to somatic mutations or chromosome
aberrations, the karyotype or phenotype of a
monozygotic twin gestation can be different
–Most reported cases describe postzygotic loss of
the Y chromosome in one 46,XY twin resulting in
a phenotypicallyfemale twin with Turner
syndrome (45,X)
6
•The phenotype of the resultant twins was one
male and one female
•Karyotype analyses revealed both to be
46,XX/46,XY genetic mosaics

7. Diagnosis of Multifetal Gestation
Diagnosis twin px
•HX
–Family Hx
–Advanced age
–Obesity
–Recent use of clomiphene citrate or
gonadotropins
•Clinical Examination
–Large for date Ux
–Excessive maternal weight gain
–Polyhydramnios
–Multiplicity of small parts, FHB
•Sonography
•Other Diagnostic Aids
–Abdominal radiography
–MRI
Differential Diagnosis
•Singleton Pregnancy
–Inaccurate dates may give a false impression of the
duration of the pregnancy, and the fetus may be
larger than expected.
•Polyhydramnios
•Hydatidiform Mole
•Abdominal Tumors Complicating Pregnancy
7

8. Determination of Chorionicity
•Accuracy: 98%
•Sonographic Evaluation
–DCDA: twin-peak sign (lambda or delta sign):
–MCDA: T sign
•difficult to visualize amnion before 8
weeks’
–In this case number of yolk sacs usually
correlates with number of amnions
•four features
oNumber of placental
oThickness of dividing membrane
–≥2 (4 layers) mm: DC & <2 mm: MC
oPresence of dividing membrane
–Lack of this -MCMA
oFetal gender
–differing -DCDA
–Same -additional measures
•Late in Px cord entanglement identifies a
monoamnionicgestation
•Overall, chorionicitycan be correctly
determined with sonography before 24 weeks
in approximately 95 percent of cases
8

9. •Although (correlation Bn number
of yolk sacs & amnions) is nearly
always true,
–there have been case reports of
two yolk sacs in early pregnancy in
twins later confirmed to be
monoamniotic
Placental Examination
•one clamp for each cord
•Collect cord blood after delivery of the other twin
•preserve the attachmentof the amnion and
chorion
–MC: one common amnionic sac, or with juxtaposed
amnions not separated by chorion arising between the
fetuses
–DC: adjacent amnions are separated by chorion
•dizygotic or monozygotic, but dizygosityis more common
–Different blood types confirm dizygosity
•But, same blood type in each fetus does not confirm
monozygosity
9

10. Undetermined Chorionicity
•After 2
nd
trimester, the sensitivity
and specificity of ultrasound to
diagnose chorionicity decreases
•Pregnancies are described as
“undetermined chorionicity” in
cases of concordant fetal gender
and difficult/delayed assignment of
chorionicity” and in such cases
monochorionicityis assumed unless
proven otherwise
•Gestational age
–use the measurement of the largest
fetus to date twin pregnancy
•Fetal anomalies
–Fetuses of multiple pregnancies are at
increased risk for structural
malformation and genetic
abnormalities.
10

11. Maternal physiological adaptations & Prenatal Care
•higher serum B-hCGlevels ➔Nausea and vomiting in excess
•Normal maternal blood volume expansion is greater
–40 to 50% in single fetus, but 50 to 60 % with twins–an additional 500 mL
•increased iron and folate requirements predispose to a greater prevalence of
maternal anemia.
•Average blood loss with vaginal delivery of twins is 1000 mL, or twice that
with a single fetus
•Cardiac output –increased
•pulmonary function tests –same as singleton
•large size and weight of uterus
•If hydramniosdevelops, maternal renal function may become seriously
impaired, most likely as the consequence of obstructive uropathy
11

12. Prenatal care
•Supplementation of Iron & folic acid: Iron 60 to
120 mg per day, Folic acid 1mg/day
•Nutrition -increased caloric intake by 300
kcal/day, equivalent to an extra snack, above
that of singleton pregnancy.
•Rest -Limited physical activities; early work
leave.
•Frequent ANC follow up
–uncomplicated twin pregnancy
•Weeks 4 to 24: monthly
•Weeks 24 to 32: every two weeks
•Weeks 32 to 38: a prenatal visit every week
–higher order multiples and complicated multiple
pregnancies, more frequent follow up is required.
•Each visit: ? signs and symptoms suggestive of
complications (PIH, PTL, PROM)
–advice on danger symptoms/signs of preeclampsia,
abruptio placentae, preterm labor and PROM
•Birth preparedness and on the need for
hospital delivery with Cesarean Section facility
–Referral to tertiary centers is recommended for
MC and/or MA twins
Test of fetal well being
•Serial growth monitoring (ultrasound every 3-4
wks) especially in monochorionic twins
•Antepartum fetal surveillance starting from
–28 wks for monochorionic, undetermined
chorionicity and other complicated twins
–32 weeks of gestation for uncomplicated twins,
every week is indicated.
•Non-stress testing (If there is CTG in the
facility)
•Biophysical profile/modified biophysical profile
•Assessing amniotic fluid (deepest vertical pool)
12

13. Pregnancy Complications
•~ 4X: infant mortality rate
•2X: Preeclampsia, PPH, and
maternal death
•↑peripartum hysterectomy,
depression
•Perinatal mortality of
•MC twins = (6-12)XDC twins
•IUFD is five times higher in MC (7.6%) vs.
DC (1.5%) twin pregnancies
•Birth weight
–more likely to be low birth weight
•Duration of Gestation
–As the number of fetuses increases,
the duration of gestation decreases
•Preterm Birth
•Prolonged Pregnancy
–a twin pregnancy of 40 weeks or more should
be considered Postterm
•Long-Term Infant Development
–Delayed
13

14. Maternal complications:
•Hyperemesis
•Anemia;
•Miscarriage;
•Pregnancy-induced hypertension and
pre-eclampsia;
•Polyhydramnios (excess amniotic fluid);
•Uterine inertia (poor contractions
during labor);
•Post-partum hemorrhage (uterine
atony, retained placenta).
Placental/fetal complications:
•Placenta previa;
•Abruptio placentae;
•Placental insufficiency;
•Preterm delivery;
•low birth weight;
•Malpresentations;
•Cord prolapse;
•Congenital anomalies (especially in
monozygotic).
Complications unique to multiple
pregnancies:
•Conjoined twins
•Monoamniotic Twins
•Interlocking of twin
•TAPS:Twinanemia-polycythemia
sequence
•TRAP sequence:Twinreversed arterial
perfusion
•Cotwin death: Single intrauterine fetal
death
14

15. Overview of the Incidence of Twin Pregnancy Zygosity and
Corresponding Twin-Specific Complications
15

16. Abortion
•Spontaneous abortion is more likely
with multiple fetuses
Congenital Malformations
•Anomalies in monozygotic twins
generally fall into one of three
categories:
•1. Defects twinning itself
–a process that some consider to be a
teratogenic event.
oconjoined twinning
oacardiacanomaly
oneural-tube defects
oHoloprosencephaly
oSirenomelia
•2. Defects vascular interchange
in monochorionic twins
–Vascular anastomoses: acardia
–Cotwin death →intravascular
coagulation develops, emboli to the
living twin
•These anastomoses may also transmit
dramatic blood pressure fluctuations,
causing defects such as microcephaly,
hydranencephaly, intestinal atresia,
aplasia cutis, or limb amputation.
•3. Defects fetal crowding
–talipes equinovarus (clubfoot)
–congenital hip dislocation.
–Dizygotic twins are also subject to
these
16

17. •division on days 8 to 12
•1% of MZs, 1 in 20 MCs
•High mortality fetal abnormalities
& spontaneous miscarriage
•Rate of TTTS in MCMAs is lower
than the rate reported in MCDAs
•Umbilical cords frequently entangle -
? Fetal death
•Clinicopathologic diagnosis
–No intertwin dividing membrane
–A single placenta that is not fused
–Same sex (a rare exception is
monovulardispermictwinning
Prenatal diagnosis -US
•one yolk sac with two fetal poles
•No intertwin membrane
•one placental disk
•Same-sex fetuses
•Cord entanglement: pathognomonic
for monoamniotic twins
Fetal and neonatal complications
•Cord entanglement
•Congenital anomalies -18 to 28% -
so fetal echocardiography
•Perinatal mortality
–After 20 weeks, perinatal mortality
~15% preterm birth, congenital
anomalies, TTTS, or cord entanglement
17

18. Obstetric care for MCMAs
•Screening for aneuploidy
–risk of Down syndrome -same or lower
than in a singleton
–NT, serum screening test
–If +ve serum screening →CVS,
amniocentesis
•Management of discordant anomalies
–One normal & other anomalous
–risk for preterm delivery, demise, and
other perinatal complications
–Selective fetal reduction by cord
ligation to prevent complications to the co-
twin from single twin demise
–cord transection to prevent future
complications from cord entanglement is
an option
•Screening for twin-twin transfusion
–lower rate of TTTS than diamniotic twins
(2 –6% Vs 9 -15%)
–Management of TTTS and TAPS is similar
to that in diamniotic twins
•Admission for close fetal monitoring
–admit at 26 to 28 weeks
–If fetal testing remains reassuring and no
other intervening indications arise,
•cesarean delivery is performed at 32 -34
weeks
–A 2
nd
course of betamethasone can be
given before this
–ACS: at 28
th
week →rescue @ <34 weeks
•Fetal monitoring: FHR, doppler,
•Death of one twin
–No clear mgt guide
18

19. •MZ
1) Conjoined Twins
•1.5 per 100,000 births
•division at or after day 13
–incomplete anatomic separation between
monozygotic twins
•Affect females > males
•Based on site of fusion:
–Thoracoomphalopagus (chest, abdomen, or
both): 74%
–Thoracopagus or xiphopagus (chest), 40%
–Omphalopagus (abdomen): 34%
–Pygopagus (buttocks): 18%
–Ischiopagus (Ischium): 6%
–Craniopagus (head): 2%
•May be: Symmetrical / Asymmetrical
•Delivery: CS
19
Possible outcomes of monozygotic twinning

20. 2) Vascular Anastomoses in MCs
•Anastomoses
–Superficial -Bidirectional
•AA (75%)
•VV (50%)
–Deep -Unidirectional
•AV Anastomosis (50%)
•Deep in the villi
•Occurs through capillaries
•TTTS: Twin-Twin Transfusion Syndrome
–Oligohydramnios/polyhydramnios sequence (SDP > 8 & < 2)
–weight discordancy -? growth discordance or restriction
–Hemoglobin differences
–five classic stages
–severe, oligohydramnios in the donor's sac leads to a "stuck
twin" appearance
•TAPS: Twin Anemia–Polycythemia Sequence
–MCA-PSV) is >1.5 MoM in donor twin and < 0.8 MoM in
receiver
–Postnatal diagnosis
•color difference: donor (pale / pinkish) & recipient (dark)
•hemoglobin difference ≥ 8 g/dL
•TRAP: Twin Reversed-Arterial-Perfusion Sequence
20
3 types of anastomoses

21. Twin-Twin Transfusion Syndrome
•Prevalence: 1 to 3 cases per 10,000 births
•Recipient
–Polycythemic (plethoric) →
hyperbilirubinemia and kernicterus
–Circulatory overload from heart failure and
severe hypervolemia and hyperviscosity→
hydrops
–Occlusive thrombosis
•Donor twin
–Pale, oligohydramnios
•Diagnosis
–Poly/olisequence
–Hgb differences greater than 5 g/dl
–Inter twin birth weight difference > 20%
–Monochorionicity, and same sex
•Fetal Brain Damage
–Cerebral palsy, microcephaly, porencephaly,
and multicystic encephalomalacia 
ischemic necrosis
•Quintero staging
–Stage I
•Poly/olisequence
•Doppler indices (UA, UV, DV) in both twins are
normal
•Donor’s bladder is visible
–Stage II: donor’s bladder is not visualized
–Stage III: abnormal doppler indices in either
–Stage IV: ascites or frank hydrops in either
twin
–Stage V: demise of either fetus
•Myocardial performance index (MPI) or Tei
index
–Doppler index of ventricular function
–Earlier diagnosis of cardiomyopathy in the
recipient twin
21

22. Why big & Small
Donor
•Hypovolemia ➔Stimulate Vasopressin & RAS ➔↓Urine production ➔
Oligohydramnios
Recipient
•Hypervolemia ➔Atrial Natriuretic Peptide & Brain Natriuretic peptide ➔↑Urine
production ➔Polyhydramnios
–As the disease progress Vasopressin & RAS pass from donor to recipient & ↓Urine
production
–Due to this as time goes polyhydramnios resolves & excess fluid starts to accumulate in
recipient’s body
–This volume overload ➔Cardiomegaly, cardiac hypertrophy & generally cardiac
dysfunction
–Due to fluid leakage from vessels ➔Hydrops
•Pleural & pericardial effusion
•Ascites, SC edema
22

23. Management depends on quinterostaging
•stage I TTTS
Asymptomatic
–expectant management rather than invasive
therapy (Grade 2C)
–75% of cases remain stable without
intervention
–weekly ultrasound -? progression
–weekly doppler -MCA-PSV & BPP
•beginning at 18 and 30 weeks
–Delivery: 36 to 37 weeks
Symptomatic
–respiratory distress, preterm contractions,
short cervix (≤25 mm) severe
polyhydramnios
–16 to 26 weeks: fetoscopiclaser ablation
–> 26 wk: amnioreduction
•stage II to IV TTTS
16 to 26 weeks
–laser ablation of anastomoses
–Selective feticide when
•life-threatening anomaly in one of the fetuses,
after failed laser ablation, or
•TAPS or recurrent TTTS occurs soon after
laser therapy
After 26 weeks
–serial amnioreduction rather than laser
ablation
•stage V TTTS
23

24. Twin Anemia–Polycythemia Sequence
•3 to 5 percent of monochorionic
pregnancies
•Diagnosis
–significant hemoglobin differences
•Donor: MCA PSV >1.5 MoM
•Recipient: MCA PSV <1 MoM
–No discrepancies in amnionic fluid
•Staging
–Stage 1: MCA-PSV >1.5 MoM & <1.0
MoM
–Stage 2: MCA-PSV >1.7 & <0.8 MoM
–Stage 3
•Stage 1 / 2 + cardiac compromise of
donor by any of the following:
–Absent or reversed end-diastolic velocity in
the UA
–Pulsatile flow in the UV
–Increased pulsatilityindex
–Reversed flow in the DV
–Stage 4: hydrops of donor
–Stage 5: Demise of either
•Treatment
–reserved for stage > II TAPS
–Options
oexpectant management
olaser surgery
oin utero transfusion
oselective feticide
oearly delivery
24

25. Twin Reversed-Arterial-Perfusion
Sequence
•TRAP
•1 case in 35,000births
•Donor shows features of heart
failure
•Recipient lacks a heart (acardius)
•a large artery-to-artery placental
shunt
•
25

26. Hydatidiform Mole with Coexisting Normal Fetus
•normal fetus + molar
–Complete mole: diploid
•multiple small anechoic cysts
–Partial mole: triploid
•Prevalence: 1 in 22,000 to 1 in
100,000 pregnancies
•live birth rates: 20 -40 percent
•complications of expectant
management
–vaginal bleeding, HEG, thyrotoxicosis
–early-onset preeclampsia
•risk of persistent trophoblastic
disease is similar whether the
pregnancy is terminated or not (W
25
th
)
•UTD 2021
–These patients may continue the
pregnancy under careful monitoring
–They should be evaluated and managed
by a gynecologic oncologist with
expertise in gestational trophoblastic
disease and a maternal-fetal medicine
specialist, if possible
26

27. Discordant growth
•Discordancy in monochorionic twins is usually attributed to
placental vascular anastomoses that cause hemodynamic
imbalance between the twins
•Diagnosis
–Percent discordancy =
•[(Wt of larger –Wt of smaller) ÷Wt of larger] X 100
–discordancy > 25 –30% most accurately predicts an adverse
perinatal outcome
•Management
–Sonographic monitoring of growth within a twin pair -mainstay in
management
–Delivery is usually not performed for size discordancy alone,
except occasionally at advanced gestational ages
•sIUGRoccurs when there is unequal placental sharing
which leads to suboptimal growth of one twin
–Usually in MC twins (10–15% of all MC twins) –UTD 2021
•usually develops late in the second and early third
trimester
•incidence of IUGR is similar in both DC and MC
twin pregnancies, but pathogenesis is different
oMC: Unequal placental sharing
–Discordancy is usually attributed to placental
vascular anastomoses that cause
hemodynamic imbalance between the twins
oDC:
–Histological placental abnormality
–Different inherent growth potential
•Fetuses may have different genetic growth
potential
–Suboptimal implantation site for one placenta
•Placentas are separate and require more
implantation space, one placenta might have a
suboptimal implantation site
27

28. Diagnostic approach of growth discrepancy
•TAPS, TTTS & sFGR are not necessarily
mutually exclusive of each other and can
present together in any combination
•1
st
Determine Chorionicity (MC/DC)
•If MC →US @ 16 –18 wk to assess for AF
➔
–Poly-oli(>8 & < 2 cm): TTTS
–No Poly-oli+ MCA PSV (26-28 week: > 1.5 Mom
& < 0.8 Mom): TAPS
–No Poly-oli+ EFW < 10
th
centile (Growth
discordance ≥ 25%): sIUGR
•UA doppler study of MC twins with sIUGRallows
definition of prognosis and potential morbidity.
•Hemodynamically unbalanced
–TTTS, TAPS
•Hemodynamically balanced
–sIUGR
–but since placental share is not proportion
•Resistance in UA of growth restricted fetus is much
higher →suboptimal fetal growth
Diagnosis of sFGR –UTD 2021
•Estimated fetal weight (EFW) < 3
rd
percentile
of one fetus or
•At least two of the four following criteria:
–EFW <10
th
percentile for one twin
–AC <10
th
percentile for one twin
–Weight discordance ≥25%
–UA PI >95
th
percentile for the smaller twin
28

29. sIUGRClassification based on UA doppler study (MC)
Type 1 sFGR
•UA D-study: N (+ve flow)
–persistently forward UA end-
diastolic velocity
•small number of arterioarterial
anastomoses
•Mild wtdiscordance
•favorable outcome for both
twins
–lowest risk for unanticipated
fetal demise,
•at elevated TAPS in up to 38% of
cases
•Planned Delivery: 34-36 wk
weeks gestation
Type 3 sFGR
•UA D-study: Intermittent -A/R EDF
–Pathognomonic: variable flow
pattern that cycles between
forward, absent, and reversed flow
over a short interval
•Larger A-A anastomosis
–allows perfusion of oxygen and
nutrients from the larger fetus to
a portion of the smaller twin's
placenta
•is associated with the largest degree
of placental territory discordance
•unpredictable clinical course
–Intermediate prognosis, due to
the more unstable hemodynamic
environment
•Commonly survive to ≥32 weeks
Type 2 sFGR
•UA D-study
–fixed A/R -EDF
•midtrimesterdeterioration of
the growth-restricted fetus
•Poorest prognosis
–due to the significant risk of
single fetal demise and
preterm birth
•Prenatal therapy (cord
occlusion, laser coagulation of
placental anastomoses)
•Delivery is 26-32 weeks
gestation
29

30. 30

31. Surveillance
•Serial Sonography
–MC twins: Every 2 weeks
–DC twins: Every 2-4 weeks
•Fetal Surveillance
–NST, BPP, and UA Doppler assessment
•None has been assessed in appropriately
sized prospective trials
–unlike singleton or DC twins with
IUGR,
•UA Doppler cannot be used as a
predictor of imminent fetal death, DV
Doppler seems the best alternative
–If discordancy in MC twin pregnancy
→UA Doppler studies in smaller fetus
may help guide management
•With uncomplicated DC multifetal
gestations, use of antepartum
surveillance has not improved
perinatal outcomes
–ACOG (2016) recommends that
•antepartum testing be performed in
multifetal gestations for indications
similar to those for singleton fetuses
•Data are limited to establish the
optimal timing of delivery of twins
for size discordancy alone
31

32. Fetal demise
32
•US -amorphous material (fetus evanescence)
•Fetus compressus
–unlike fetus papyraceous, shows the flattening of the just-
born twin, due to pressure effects, but it is not
incorporated within the membranes or placenta of the
live born twin due to inadequate time
•fetus papyraceous
–a tan ovoid mass compressed against the fetal membranes
–mechanical compression of the small fetus and loss of
fluid such that it resembles parchment paper
•vanishing twin
–Usually not clinically recognized
–Surviving twin has an excellent prognosis
•Co twin death
–↑ed risk of spontaneous and iatrogenic preterm delivery
fetus papyraceous

33. Cotwin death
•2.4 to 6.8% of twin pregnancies
•More common among
–Monochorionic twins
•3 -4 fold increased compared to dichorionic
pregnancies
–Twins with chromosomal or structural
abnormality
–Higher order pregnancies
•Factor for increased the risk of death
–Same-sex
–Weight discordance
•Effect on the Surviving Fetus or Fetuses
depends on:
–Gestational age at demise
•In 1
st
trimester risk is not clear, but congenital
anomalies and cerebral palsy may be attributed
•After viability there is risk of brain injury,
multicystic encephalomalacia as high as 20%.
33
–Chorionicity
•Risk of MC > DC
•Abnormalities reported among surviving
twins include
–Necrosis and cavitation of the cerebral white
matter
–Cerebellar necrosis
–Multicystic encephalomalacia
–Hydrocephalus
–Microcephaly
–Hemorrhagic infarction
–Others -ischemic bowel lesions, intestinal
atresia, renal cortical necrosis, and cystic
renal dysplasia

34. Management
•The optimal treatment is not well
established
–Recommendations have been based on
expert opinion.
•Clinical management depends on :
–The gestational age or fetal lung maturity
–Compromise of the surviving fetus or
fetuses
–Coexisting maternal illness or obstetric
complications
•If from maternal complications; mgt is based
on diagnosis and status of both mother and
surviving twin
34
DC twins
•Death of one twin is not, by itself, a
strong indication for delivery
•Previable DC pregnancies managed
expectantly
•Fetal surveillance considered once
viability is achieved
–Weekly BPP and NST
–Delivery if :
•37 wks OR earlier if lung maturity is
documented
•A condition affecting both twins is present
–e.g. preeclampsia, chorioamnionitis
•Non reassuring fetal tests
•C/S only for obstetric indications

35. MC twins
•Morbidity almost always due to vascular
anastomoses
•Before viability is challenging
•Patients should be counseled regarding the risk
of multiorgan injury including multicystic
encephalomalacia and termination
•The risk of cerebral palsy in the surviving co-
twin may be as high as 20 %
•It is difficult to predict which surviving
monochorionic twins will develop cerebral
injury
•Rapid delivery of the co-twin following single
IUFD in a monochorionic pregnancy is unlikely
to improve the outcome.
•Conservative management recommended if
continuation of pregnancy exceeds the risk of
preterm delivery & its complications.
35
•Prompt delivery of MC twins should be
considered if fetal assessment suggests
impending death of one twin
•At 32 to 34 weeks, administering a course of
glucocorticoids and delivery 48 hours later is
an option
•Before 32 weeks, it is probably best to allow
the pregnancy to continue
•NST and BPP weekly, but may not reflect
subtle CNS changes
•After Delivery
–Autopsy for the stillborn fetus, and
–Pathologic examination of the placenta are
recommended
•psychological or bereavement counseling

36. Maternal complications of cotwin death
Consumptive coagulopathy
•Coagulation derangement is
uncommon in multifetal pregnancy
with co-twin death
•Only a few cases of laboratory
changes consistent with a subclinical
coagulopathy have been reported
•Baseline PT, PTT, fibrinogen level, and
platelet count are recommended. If
normal, surveillance is not performed.
•Platelet count and fibrinogen level are
desirable prior to delivery
•Cesarean delivery rates seem to be
increased (NRBPP)
•Vaginal delivery is not contraindicated
and cesarean delivery is reserved for
routine obstetric indications.
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37. •During antepartum surveillance tests of well-being, abnormal results in one
twin, but not the other, pose a particular dilemma
•Delivery may be the best option for the compromised fetus yet may result
in death from immaturity of the cotwin
•If fetal lung maturity is confirmed, salvage of both the healthy fetus and its
jeopardized sibling is possible
•Unfortunately, ideal management if twins are immature is problematic
•Often the compromised fetus is severely growth restricted or anomalous
•Chromosomal abnormality identification in one fetus allows rational
decisions regarding interventions
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38. Preterm Birth
•Preterm labor is common in multifetal pregnancies
and may complicate up to
•50 percent of twin,
•75 percent of triplet, and
•90 percent of quadruplet pregnancies
Prevention
•Limited physical activity, early work leave, more
frequent health care visits and sonographic
examinations
•Bed rest–especially through hospitalization
•Prophylactic Tocolysis –no recommended
•Progesterone Therapy
–not effective for multifetal gestations, even to those with
a shortened cervix
•Prophylactic cerclage -no recommended
–Rescue cerclage in a 2
nd
trimester may be beneficial
•Pessary use –not recommended
Treatment of Preterm Labor
•Corticosteroids for Lung Maturation
–Same as singleton gestations
•Tocolysis does not improve neonatal outcomes
Preterm Premature Membrane Rupture
•Steroids, antibiotics, MgSO4 (?)
Delayed Delivery of Second Twin (W 25
th
)
•may be advantageous for undelivered fetus(es)
•But, no tocolytics, prophylactic antimicrobials, or
cerclage
•Good candidates: 23 to 26 weeks
–Counsel particularly regarding the potential for serious,
life-threatening infection
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39. Labor & Delivery
Timing of delivery
•MCMA: 32-34 wks of GA after steroids by cesarean
section
•MCDAs
–Uncomplicated: 34 -38 wks (FMOH : 36 –38)
–Complicated: depends on the underlying pathology
•DCDAs
–Uncomplicated: 40 wks
•Elective cesarean sections for twin pregnancy should be
done at 38wks of gestation
–Complicated: depends on the underlying pathology
•Avoid Induction & augmentation
•Cotwin death
–Term -deliver without delay
–Preterm -prolonging the pregnancy for the benefit of
increased maturity of the surviving twin is recommended.
•Triplet pregnancies: ≥ 36 wks
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•Route of delivery
–Cephalic –C : VD
–NV –Any: CS
•Both breech: Leg of tBwill hyperexnedtA➔cervical injury
•NV –C: Interlocking of Twins

40. Vaginal Delivery
•Cephalic-Cephalic Presentation
–cesarean delivery does not improve
neonatal outcome when both twins are
cephalic
•Cephalic-Non cephalic Presentation
–optimal delivery route is controversial
–when the estimated fetal weight is > 1500
g, vaginal delivery of a nonvertex second
twin is reasonable
•Vaginal Delivery of the Second Twin
–If contractions do not resume within
approximately 10 minutes, dilute oxytocin
may be used to stimulate contractions.
–the safest interval between delivery of the
first and second twins was commonly cited
as < 30 minutes
•Internal Podalic Version
–conversion of the fetal presentation from a
transverse / cephalic to a breech
presentation ➔obstetrician grasps the
fetal feet to then effect delivery by breech
extraction
–Upward pressure on the head by an
abdominal hand is applied as downward
traction is exerted on the feet
•Indications
–Second twin in transverse lie
–Failure of external cephalic version
–Transverse lie in multipara with full cervical
dilatation
–Fetus (dead or too preterm) to survive
after a caesarean section
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41. Contraindications for IPV
•A scar on the uterus from a previous
operation
•Threatened rupture of the uterus
•Multiple pregnancy
•Congenital malformation of the uterus
•Major degree of pelvic contraction
•Placenta praeviadegree III and IV
•Stay with the woman and continue
monitoring her and the fetal heart rate
closely.
•When strong contractions restart, ask
the mother to bear down when she
feels ready.
•If spontaneous delivery does not occur
within 2 hours of good contractions,
do operative vaginal delivery or CS
depending on the case.
•After delivery of the second baby,
resuscitate if necessary
•Make sure there is no more baby and
proceed to 3
rd
stage management
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42. Selective reduction Vs termination
Selective Reduction
•as a therapeutic intervention to enhance
survival of the remaining
•can be performed transcervically,
transvaginally, or transabdominally, but the
transabdominal route is usually easiest
–inject potassium chloride into the thorax,
which causes asystole,
•Transabdominal: 10 and 13 weeks’
–This gestational age is chosen because most
spontaneous abortions have already occurred
•Indication: Higher order pregnancy
–overall number of fetuses in the gestation is
reduced by terminating one or more fetuses
mostly chosen randomly
Selective Termination
•performed later in gestation than selective
reduction
•entails greater risk
•not performed unless the anomaly is
severe but not lethal
•Technique
–DC: Potassium chloride is injected into the
thoracic cavity
–MC: difficult
•Indication: chromosomal, structural, or
genetic abnormality
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43. •A 37-year-old G1 comes to establish prenatal care with you
after being discharged from her reproductive endocrinologist.
This pregnancy was conceived via single embryo transfer in
vitro fertilization. Which one of the following is true regarding
her situation?
–a. Assisted reproductive technology increases the
incidence of monozygotic twins two-to fivefold.
–b. If a single zygote splits 8 days post fertilization, a monochorionic
diamnionic twin gestation results.
–c. Because this pregnancy is known to have begun with one
embryo, you can be certain that she will have monochorionic
twins, but amnionicitydepends on timing of split.
–d. All of the above
•A 29-year-old G1P1 conceived dichorionic twins via
gonadotropin stimulation and intrauterine insemination (IUI)
with her husband’s semen. Her blood type is O-negative, so
prior to receiving anti-D immune globulin the neonates’ blood
type is assessed. One neonate is A-positive and the other is O-
negative. Her husband is A-positive. This finding can be
explained to the parents by describing which of the following
phenomena?
–a. Superfetation
–b. Superfecundation
–c. This is not atypical for dichorionic twins
–d. This cannot be explained without alleging infidelity or poor
technique by her reproductive endocrinologist’s office
•Which of the following statements regarding atypical twinning
is not true?
–a. Monochorionic twins are never dizygotic.
–b. Twins of opposite sex are not always dizygotic.
–c. Monochorionic twins are not always the same sex.
–d. None of the above is true
•Maternal physiological adaptation to twin pregnancy in
comparison to a singleton pregnancy is accurately described in
which of the following statements?
–a. Cardiac output increases 40% above that of a woman carrying a
singleton fetus.
–b. Blood volume expansion averages 70%, which is greater than the
40–50% seen in women carrying a singleton.
–c. The increased cardiac output in twin gestation is
primarily due to increased stroke volume rather than
increased heart rate.
–d. All of the above
•It is well known that miscarriage is more likely with a multifetal
gestation. Which of the following statements is not true?
–a. Before 12 weeks, one or more fetuses are lost in about 50% of
initial triplet pregnancies.
–b. Twins conceived via assisted reproductive techniques
are at greater risk for spontaneous loss.
–c. Spontaneous loss of a cotwin before the second trimester
occurs in 10–40% of all twin gestations.
–d. None of the above is true.
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44. •Which of the following are not beneficial
interventions for complicated monochorionic
twin pregnancies?
–a. Immediate delivery of surviving twin to prevent
neurological damage after finding of cotwin
demise.
–b. Intentional septostomy to equalize fluid and
pressure for Quintero stage II twin-twin
transfusion syndrome.
–c. Selective feticide via intracardiac injection of
potassium chloride when lethal anomaly is found
in one twin.
–d. All of the above
•Which of the following modalities provide
reassurance of a lower risk for preterm birth
in a twin gestation?
–a. Closed cervix on digital examination
–b. Cervical length over 20 mm, measured at 22–24
weeks by transvaginal ultrasound
–c. Cervical length over 20 mm, measured serially in
the second trimester by transvaginal ultrasound
–d. All of the above
•Many aspects of the care of a twin pregnancy
differ from that of a singleton. Which of the
following is different for a twin gestation?
–a. Guidelines for administration of corticosteroids
for fetal lung maturity
–b. Administration of antibiotics for latency after
preterm premature rupture of membranes
–c. Gestational age at which delivery is
recommended for a pregnancy that has
been uncomplicated
–d. None of the above
•Planned cesarean delivery has not been shown
to improve neonatal outcome and is not
advocated above vaginal delivery for which of
the following clinical scenarios?
–a. Vertex-vertex diamnionic twin gestation
–b. Breech-vertex diamnionic twin gestation
–c. Vertex-vertex monoamnionictwin gestation
–d. Vertex-vertex-transverse triamnionictriplet
gestation
44

45. •A 34-year-old G1 presents with spontaneous conception of a
trichorionic-triamnionictriplet gestation. Which of the following is
not an appropriate aspect of her early pregnancy counseling?
–a. Selective fetal reduction can be performed with ultrasound-guided
intracardiac injection of potassium chloride.
–b. She is counseled that elective fetal reduction from triplet to twin
gestation carries a 4.5% risk for loss of the entire pregnancy.
–c. She is counseled that elective reduction should be performed
because it will result in a lower rate of maternal complications,
preterm birth, and neonatal death.
–d. All of the above are appropriate aspects of your counseling.
45