Twin pregnancy

-DR.DIVYA JAIN

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.

TWINS

DIZYGOTIC2/3

MONOZYGOTIC1/3

Monochorionic monoamniotic <1%

Monochorionic diamniotic -75%

Dichorionic diamniotic -25%

DichorionicDiamniotic

SUSPICION OF TWIN 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

DIAGNOSIS

Before 10 weeks sonographic findings to determine chorionicity depends upon number of

• gestational sacs

• yolk sacs.

1. Number of Gestational Sacs

Each gestational sac forms its own placenta and chorion:

gestational sacs: DC twin

1 gestational sac with 2 identified heartbeats: MC twin

Number of Yolk Sacs

2 yolk sacs are seen in the extra-embryonal coeloma: diamniotic

1 yolk sac in most cases indicate monoamniotic twins

After 10 weeks

These sonographic signs are no longer present: gestational sacs are no longer distinctly separable, and the inter-twin membrane is formed

Diagnosis depends upon

• Placental number

• Chorionic peak sign

• Membrane characteristics.

Number of Distinct Placentas- 1placental mass: MC 2 distinct, separate placentas: DCCareful sonographic examination may help distinguish a single placenta from 2 placentas in abutment.

Presence or Absence of the Chorionic Peak (twin peak or lambda sign)-

Projecting zone of tissue of similar echotexture to the placentaTriangular in cross-section and wider at the chorionic surface of

the placenta, extending into, and tapering to a point within, the inter twin membrane.

Most often identifies DCMC: absence of the twin peak sign.

Inter-Twin Membrane CharacteristicsDC :2 layers of amnion and 2 layers of chorion.Thicker > 2 mm

MC: ≤ 2mm

If a membrane is not detected: careful evaluation to diagnose or exclude monochorionic monoamniotic twinning

Possibilities:1.Monoamniotic twinning2.Twin with complete oligohydramnios (stuck twin)

ABSENT MEMBRANE IN A MONOAMNIOTIC TWIN

LAMBDA SIGN

MONOCHORIONIC & DIAMNIONIC

T SIGN

MATERNAL COMPLICATIONS

Antepartum

hyperemesis

hydramnios

Pre eclampsia(3 fold times),eclampsia(6 fold times)

Pressure symptoms

Anaemia

Antepartum hemorrhage-

Placenta previaAbruption

Intrapartum complications

Dysfunctional labourMalpresentationsIncreased chance for operative deliveryPost partum hemorrhageRetained placenta

FOETAL COMPLICATIONS

I. Prematurity

2.DISCORDANT 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%)

• Discordant fetal growth can be due to different genetic growth potentials, structural anomaly of one fetus, or an unfavourableplacental 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.

• USG monitoring of growth within a twin pair is mainstay in management .

• The indication for delivery should take into consideration of the fetal well-being, the gestational age and serial growth velocity

MANAGEMENT

3. Single fetal demise

monochorionic

Death of one twinShift of blood

Normal twin

25% risk of co-twin death /25% risk of neurological damage in surviving twin(FOETAL DEATH SYNDROME)

• 2-6% of twins pregnancies

• Perinatal morbidity and mortality of the surviving co-twin19% perinatal death24% having serious longterm sequelae

• Morbidity of surviving fetus depend on chorionicity and consequences of prematurity

4. 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

5. TWIN-TWIN TRANSFUSION SYNDROME

• Features of TTTS are the result of hypoperfusion of the donor twin and hyperperfusion of the recipient twin.

• Oligohydramnios develops in the amniotic sac of the donor twin.

• Profound oligohydramnios can result in the stuck twinphenomenon in which the twin appears in a fixed position against the uterine wall.

• Either twin can develop hydrops fetalis. • The donor twin can become hydropic because of anemia and high-

output heart failure. • The recipient twin can become hydropic because of hypervolemia. • The recipient twin can also develop hypertension, hypertrophic

cardiomegaly, disseminated intravascular coagulation, and hyperbilirubinemia after birth

Uss of TTS….STUCK TWIN

TREATMENT FOR TTTS

• Amniotic septostomy

• Laser ablation

• Selective fetocide

• Serial amnioreduction

Serial amnioreductionsurvival 64% overall, 74% of at least one twin

Laser ablation

(55% overall survival—73% of at least one twin),

6.Acardiac foetus

Normal fetus/pump twinMinimal oxy. extracted by lower

part of Acardiac fetus

A-A anastamosesin placenta

De oxygenated blood

Umb.A

Umb. A

Fully de oxygenated

Upper part of fetus ,no growthUmb.VV-V anastomosesin placenta

Umb.V

7. Vanishing twin

Cessation of cardiac activity in a previously viable foetus

Foetus papyraceous…

8.Conjoint twins

Always monozygotic

Classification-

ThoracopagusCraniopagusischiophaguspyophagusomphalopagus

• 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.

Dichorionic twins • Ultrasound at 10–14 weeks: (a)

viability; (b) chorionicity; (c) NT: aneuploidy

• Structural anomaly scan at 20–22 weeks.

• Serial fetal growth scans e.g 24, 28, 32 and then two- to four-weekly.

• 34–36 weeks: discussion of mode of delivery and intrapartum care.

• Elective delivery at 37–38 completed weeks. Some by 40weeks

• Postnatal advice and support (hospital- and community-based) to include breastfeeding and contraceptive advice

Monochorionic twins

• Ultrasound at 10–14 weeks: (a) viability; (b) chorionicity; (c) NT: aneuploidy/TTTS

• Ultrasound surveillance for TTTS and discordant growth: at 16 weeks and then two-weekly.

• Structural anomaly scan at 20–22 weeks (including fetal ECHO).

• Fetal growth scans at two-weekly intervals until delivery.

• 32–34 weeks: discussion of mode of delivery and intrapartum care.

• Elective delivery at 36–37 completed weeks (if uncomplicated).

• Postnatal advice and support (hospital- and community-based) to include breastfeeding and contraceptive advice.

ANTENATAL CARE

PRESENTATION

• 40% of twins present as vertex/vertex,

• 35% as vertex/non-vertex,

• remaining 25% of twins present with the leading twin in a non-vertex presentation at birth .

MANAGMENT

Basic Principles-

• The presence of skilled obstetrics attendants for labor and delivery

• Anesthesiologist available

• Neonatal care personnel sufficient for resuscitation of the newborns

• Reliable IV access

• CTG

If the second twin is in non-vertex presentation, the other options include

o Assisted vaginal breech delivery or breech extraction,o Internal podalic version following by breech extraction, o ECV followed by vaginal cephalic delivery,

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• 2nd twin transverse after delivery of 1st twin

MANAGEMENT DURING LABOUR

1st stage-

• Good intrapartum care : blood, IV access, continuous FHS monitoring.

• In case of inefficient uterine contractions, oxytocin augmentation can be used.

• The criteria for diagnosing slow progress are the same as in singletons.

SECOND STAGE OF LABOUR

• Following delivery of the first twin, ergometrine 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.• 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

THIRD STAGE

• increased risk of primary PPH.

• After 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.