Multifetal PregnancyRadha VenkatakrishnanClinical LecturerWarwick Medical School

Incidence :Monozygotic twins - 4/1000 birthsDizygotic twins 2/3rds, race, age, assisted conceptionTriplets 1 in 7000 to 10,000 birthsQuadruplets 1 in 600,000 births Almost every maternal and obstetric problem occurs more frequently in multiple Pregnancy Perinatal mortality rate in twins is 5 times higher and in triplets 10 times higher than in singletons

Zygosity refers to the type of conception

Chorionicity denotes the type of placentation

Chorionicity rather than zygosity determines out outcomeZygosity and Chorionicity

Mechanism of dizygotic twinning

Fertilization of a single ovumSimilar sexGenetically identical

Fertilization of 2 separate ova

Monochorionic twinsWithin 72 hours (18-32%)3-8 days later (60-70%)

Monochorionic twins8-12 days later (1-2%)12-13 days later (0.5%)

Maternal responses

Cardiac output, GFR and renal blood flow Plasma volume by 1/3 > singletons Red cell mass 300 ml > singletons Hematocrit and hemoglobin Iron stores in 40% of women with twinsMultiple pregnancy

DiagnosisPatient profile:Etiological factors: positive past history and family history specially maternal, race, ageAssisted reproductive technologyEarly pregnancy:Hyperemesis, excessive weight gainminor complications of pregnancy such as backache, edema, varicose veins, hemorrhoids, striae, etc

Physical signsGeneral:Pallor, weight gain, excessive pedal edema/ varicose veinsPregnancy Induced Hypertension(PIH) and Pre-eclampsia (5-10times more)

Abdominal:Size > Date especially in midpregnancyMultiple fetal partsAuscultation of FHS: 2 different recordings by 2 observers and a difference > 10 bpm

Differential diagnosis

Elevation of the uterus by a distended bladderInaccurate menstrual history Hydramnios Hydatidiform moleUterine fibroidsA closely attached adnexal massFetal macrosomia (late in pregnancy)

Ultrasonography

Detect multifetal gestation 99% before 26 weeksConfirm fetal number [ 2 sacs or 2fetal heads in 2 perpendicular planes] Diagnose type and presentation and position and relation to each otherExclude congenital abnormalities/ conjoint twin

Maternal complicationsSymptoms hyperemesis, aches and pains of pregnancy worsenHypertensive disease of pregnancyPreterm deliveryPremature rupture of membranesPolyhydramniosPlacenta praeviaMalpresentationDelivery complications (operative delivery, placental abruption, cord accidents)Postpartum hemorrhage, depression

Fetal complicationsSpontaneous early pregnancy lossPrematurity Intra-uterine growth restrictionCerebral palsy - related to gestational age, 3 times in twins, > 10 times in tripletsIntrapartum traumaMonochorionic twins specific complications

Antenatal care

Routine booking investigationsFolic acid supplementationanemia treat immediatelySupport symptomatically

Serial growth scans :Dichorionic :4 weekly from 24 weeksMonochorionic : 2 weekly from 18 weeks- Liquor volume- Doppler study of umbilical artery

Intrapartum management

Presence of skilled obstetrician, anesthetist and neonatologist available at deliveryReliable intravenous accessCardiotocograph with dual monitoring capabilityPortable ultrasound scannerDelivery bed with lithotomy stirrupsObstetric forceps or vacuum apparatus active management of third stage: UterotonicsImmediate availability of bloodFacilities and staff for emergency cesarean section

Monochorionic Monoamniotic twins

3 - 12 x perinatal mortality10 x cerebral necrotic lesions

1% of monozygotic twins are monoamnionic Perinatal mortality rate of 30-50%, largely relates to a risk of intrauterine death before 32 weeks

Cord entanglement

Twin-Twin Transfusion Syndrome

Incidence : 4 - 20% of MC twins

It is characterised by an imbalance of blood flow between the twins

15 - 20% of perinatal deaths

Untreated, perinatal loss rates in the mid-trimester (80 - 100%)

Large volume amnioreduction

Amniotic Septostomy

Fetoscopic Laser Ablation

Delivery by Caesarean sectionat 34 weeks

Conjoined twins or Siamese twins

Anterior (thoracopagus)

Posterior (pygopagus)

Cephalic (craniopagus)

Caudal (ischiopagus)

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 long term sequelae

Treatment options

No optimal management

Prompt delivery -Iatrogenic prematurity risks

Conservative treatment -Subsequent handicaps

Intrauterine interventions

High order multiples

Perinatal risk increases exponentially with increasing number of fetuses

Multifetal pregnancy reduction (MFPR) at 10 to 12 weeks should be recommended for quadruplets and higher multiples

The situation with triplets is more controversial

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