Multifetal Gestation

Xiong yu

Obstetric & Gynecology Hospital, Fudan University

Incidence

twins ： 1:100。 triplets ： 1:10,000。 quadruplets ： 1:1,000,000。 quintuplets ： 1:100,000,000。

Incidence

Between 1980 and 2005,the number of live births from twin deliveries rose nearly 50 percent, and the number of higher-order multifetal births increased more than 400 percent. However, changing infertility therapy has led to slight decreases in rates of higher- order multifetal births.

Factors that Influence Twinning Race Heredity Maternal Age and Parity Nutritional Factors Pituitary Gonadotropin Infertility Therapy Assisted Reproductive Technology (ART)

Factors that Influence Twinning Dizygotic twins ： 2/3 influenced remarkably by race, heredity, maternal age,

parity, and, especially, fertility treatment

monozygotic twins ： 1/3 1:250 independent of race, heredity, age, and parity

Dizygotic twins Two ovums， Two sperms。 Different Gene：

1. appearance: different or alike2. gender ： same or different

Placenta： two placentas fuse to one placenta, twin peak, no communicated

blood vessel Diamnionic/dichorionic (DA/DC)

Placenta and membrane of dizygotic twins

two placentastwo amnions two chorions

fused placentatwo amnions fused chorion

Monozygotic twins One ovum， One

sperm。 Same Gene：

1. appearance: same

2. gender ： same Four types:

1. DCDA

2. MCDA

3. MCMA

4. MCMA conjoined twins

Conjoined twins (1:60,000)

Importance of Chorionicity

Chorionicity determine the outcome of twins, while not zygoticity.

Compare to DCDA, higher incidence of abortion, perinatal mortality, preterm, FGR and morfamation in MC twins.

If one twin died in MC twins, the other twin will be in high risk of sudden death and nervous system effects.

-----Determination of chorionicity correctly is important to predict the prognosis and twin-specific complications.

Outcomes of Different Chorionic Twins

Sonographic Evaluation （ prenatal)--- Dichorionic Diamniotic twins (DCDA)

first trimester （ before 8 weeks）：two sacs

after 14 weeks ： opposite gender （ dizygotic）

10-14 weeks：1. two separate placentas2. dividing membrane: 2 mm≧

3. one fused placenta, twin peak

Sonographic Evaluation （ prenatal)--- Monochorionic Diamniotic twins (MCDA)

first trimester （ before 8 weeks）： one sac

after 14 weeks ： same gender

10-14 weeks： dividing membrane: ‹2mm one placenta ： none twin peak， T sig

n

divided amnion

no divided amnion

Sonographic Evaluation （ prenatal)--- Monochorionic Monoamniotic twins (MCMA)

Determination of Chorionicity (postnatal)

Gender1. Opposite: DC2. Same: DC or MC

Placenta: two placentas ： DC one placenta: number of membrane

partition that separated twin fetuses 1. 0 ： MCMA2. 2 ： MCDA3. 3 or 4 ： DCDA

Complications(maternal) Anemia: 74.6%

Preeclampsia: 30%

Postpartum hemorrhage: 2 times (average blood loss with vaginal delivery of twins is 1000 mL)

Higher rate of CS: 53.3%

Emergent peripartum hysterectomy: 3 times (twins), 24 times (triplets of quadruplets)

Heart failure

Depressive symptoms : 50%

Maternal death

Complications (fetal)

Abotion (3 times in twins, MC:DC 18:1) Malformations Placental vascular anastomosis (twin-twin transfusion

syndrome, TTTS) Fetal-growth restriction Preterm delivery (60% twins, 93% triplets) Perinatal mortality

Outcomes in twins

Twin-specific ComplicationsTwin pregnancy

Dizygotic twins Monozygotic twins

DCDADCDA MCDA MCMA

TTTS TAPS TRAPConjoined Twins

70% 30%

35% 65% <1%

Discordant Twins (one IUGR)

Discordant Twins (sIUGR)

1. 1. Twin-Twin Transfusion Syndrome (TTTS)Twin-Twin Transfusion Syndrome (TTTS)Definition blood is transfused from a donor twin to its recipient sibling. the donor becomes anemic and its growth may be restricted. the recipient becomes polycythemic and may develop circulatory overload

manifest as hydrops. donor twin is pale, and its recipient sibling is plethoric.

Vascular Anastomoses With rare exceptions, vascular anastomoses between twin

s are present only in monochorionic twin placentas.

Three types:

Arterio-Arterial(A-A): most common, 75% monochorionic twin placentas.

Venous –Venous(V-V): 50%

Arterio-Venous(A-V): 50%

Vascular Anastomoses in TTTS Pure superficial vascular anastomoses occur TTTS

rarely.

Pure deep anastomosis almost occurr TTTS.

Superficial and deep anastomosis result to 79% T

TTS.

Functional arterial anastomosis with compensation

for twins bloodstream, there is a lower incidence of

TTTS in arterial anastomosis.

No A-A anastomosis, 61% twins will occur TTTS.

A-A anastomosis, 15% twins will occur TTTS.

Fetal Brain Damage

Quarello (2007): 315 liveborn fetuses with TTTS

Cerebral abnormalities: 8%

Cerebral palsy, microcephaly, porencephaly, and multicystic encephalomalacia

Donor: ischemia results from hypotension, anemia, or both.

Recipient: ischemia develops from blood pressure instability and episodes of severe hypotension

Fetal Brain Damage (one twin demise)

Pharoah and Adi (2000): 348 survivors whose twin sibling

had died in utero.

The prevalence of cerebral palsy was 83 per 1000 live bi

rths–--a 40-fold increased risk over baseline.

Even with delivery immediately after the co-twin demise is

recognized, the hypotension that occurs at the moment of d

eath has likely already caused irreversible damage.

Diagnosis (Prenatal)1. monochorionicity2. same-sex gender 3. hydramnios defined if the largest vertical pocket is > 8 cm i

n one twin and oligohydramnios defined if the largest vertical pocket is < 2 cm in the other twin

4. umbilical cord size discrepancy5. cardiac dysfunction in the recipient twin with hydramnios 6. abnormal umbilical vessel or ductus venosus Doppler veloc

imetry 7. significant growth discordance

Quintero staging systemQuintero staging system

Stage I: polyhydramnios(>8cm) in recipient / aligodramnios(<2cm) in donor, but urine still visible sonographically within the donor twin's but urine still visible sonographically within the donor twin's bladder bladder

Stage II: criteria of stage I, but urine is not visible within the donor's criteria of stage I, but urine is not visible within the donor's bladder bladder

Stage III: criteria of stage II and abnormal Doppler studies of the criteria of stage II and abnormal Doppler studies of the umbilical artery, ductus venosus, or umbilical vein. umbilical artery, ductus venosus, or umbilical vein.

Such as Such as AEDV or AEDF in donor, ductus venosusductus venosus regurgitation or Umbilical vein pulsatility in recipient.

Stage IV: ascites or frank hydrops in either twinascites or frank hydrops in either twin

Stage V: demise of either fetus demise of either fetus

Diagnosis (Postnatal) MCDA:

1. number of placenta, chorionic membrane, amniotic membrane

2.2. same-sex gendersame-sex gender

Examination in neonate：1.1. discordancediscordance in hemoglobin: ≥5g/l

2.2. discordancediscordance in red blood cell: ≥ 109

3.3. ddiscordance in iscordance in body weight : ≥15-20%

Treatment 1

Conservative treatment：Observation and RestDrug：

---Indomethacin： reduced the volume of amniotic fluid ---Digoxin： acting on donor, increase cardiac output and relieve symptoms

----Not the main method, may be useful to one fetal but have adverse effects on the other twin.

Treatment 2 Invasive treatment

Amnioreduction

Septostomy (intentional creation of a communication in the

dividing amnionic membrane)

Fetoscopic Laser Occlusion of Chorioangiopagous Vessels (FLOC)

Selective feticide

RFA（ Radio Frequency Ablation ） Umbilical cord ligation

Monopolar or Bipolar coagulation

2.TRAP (Twin Reversed Arterial Perfusion) Sequence Incidence: rare, about 1 in 35,000 births Definition ： one twin has an absent, rudimentary, or nonfunctioning

heart (acardiac twin) ， the other twin is normal (pump twin). TRAP sequence has been associated with adverse perinatal outcomes.

Placentation: majority of acradic twins is monochorionic diamniotic. vascular anastomoses: arterial-to-arterial (A-A)

Diagnosis

The diagnosis is made with ultrasound.

The features useful in the diagnosis of acardia include absence of normal cardiac structure and cardiac movement and variable structural abnormalities.

Malformations of Acardia Four groups: acardius acephalus, acardius amorphus or anideus, acardius aco

rmus, and acardius anceps or paracephalus.

Management The pump twin is usually morphologically normal, and the risk of aneuploidy is

9%. The goal of antepartum management of a pregnancy complicated by the TRAP s

equence is to maximize outcome for the structurally normal pump twin. Expectant management: serial sonographic evaluation

Selective feticide: radiofrequency ablation (RFA) of the cord of the acardius, 95% pump twin survival.

Criteria: twin weight ratio >0.70 elevated combined ventricular output elevated cardiothoracic ratio

congestive cardiac failure polyhydramnios

3. Discordant Twins (Diagnosis)

Weight Discordancy(%) =weight (large)-weight (small)/ weight (large) Diagnosis:

Weight Discordancy ≥ 25%Simple: abdominal circumferences difference ≥ 20 mm

Hollier (1999): 1370 twin pairs Weight discordancy ≥ 25%: predicts an adverse perinatal outcome. Weight discordancy ≥ 30%: relative risk of fetal death is 5.6.Weight discordancy ≥ 40%: relative risk of fetal death is 18.9.

Discordant Twins (sIUGR, MCDA)

Distinguish with TTTS

One small ， the other normal.

One oligohydramnios ， the other normal volum of amniotic fluid .

Management: Discordant Twins in DC

Before 28 weeks: follow up, ultrasound weekly.

After 28 weeks: intensive care

surveillance: daily nonstress testing (NST）terminate in time if abnormal apperance.

Management: Discordant Twins in MC

10-20% IUGR fetus will die and result in the bad outcome of nervous system in 20% survival fetus.

Treatment Protocols （ before 26 weeks）：1. Expect treatment

1. close ongoing surveillance2. terminate in time if abnormal ultrasonic apperance

2. Termination of pregnancy ： abortion3. Laser4. Selective feticide (sIUGR fetus)

4.Monoamnionic Twins 1% monozygotic twins high perinatal mortality: 17%

cord entanglement (>50%)congenital anomalypreterm birthFGRvascular anastomoses

Management problematic

unpredictability of fetal death resulting from cord entanglement

lack of an effective means of monitoring 26-28 weeks: elective hospitalization

daily: nonstress testing (NST）corticosteroids for lung maturation: betamethasone

32-34 weeks: Elective deliverya second course of betamethasone34 weeks: cesarean delivery

Delivery

When How Evaluation

Time of Delivery

According to the Chorionicity

No obvious complications： DCDA ： 37-38 weeks

MCDA： 34-36 weeks

MCMA： 32-34 weeks

Mode of Delivery 1

cephalic-cephalic: 42% Generally advocated vaginal delivery

If a first twin is cephalic, delivery can usually be accomplished spontaneously or with forceps.

Hogle (2003) perfomed an extensive literature review and concluded that planned cesarean delivery does not improve neonatal outcome when both twins are cephalic.

Muleba (2005) identified increased rates of respiratory distress in the second twin of preterm pairs regardless of the mode of delivery or corticosteroid use.

Mode of Delivery 2cephalic–noncephalic : 45% , cephalic-breech, and cephalic-transverse:

The optimal delivery route for cephalic–noncephalic twins is controversial.

A randomized study found that cesarean section and vaginal delivery were no differences in neonatal outcomes.

Prerequisite for vaginal delivery is the obstetrician's technology and experience.

As the number of trained doctors with experiences of assisted breech delivery and internal podalic version were reduced quickly, patients faced with two options: cesarean section or external podalic version on the second fetal.

Mode of Delivery 3Breech presentation:13% As in singletons, if a first fetus presents as a breech, major problems

may develop if:The fetus is unusually large, and the aftercoming head is larger

than the birth canalThe fetus is sufficiently small. The extremities and trunk may

deliver through an inadequately effaced and dilated cervix, but the head may become trapped above the cervix

The umbilical cord prolapses. Therefore, cesarean section is always recommended.

Thank you!