Multifetal Pregnancy

Radha VenkatakrishnanClinical LecturerWarwick Medical School

•Incidence :•Monozygotic twins - 4/1000 births•Dizygotic twins – 2/3rds, race, age, assisted conception•Triplets – 1 in 7000 to 10,000 births•Quadruplets – 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 outcome

Zygosity and Chorionicity

Mechanism of dizygotic twinning

• Fertilization of a single ovum

• Similar sex• Genetically identical

• Fertilization of 2 separate ova

Monochorionic twins

• Within 72 hours (18-32%) •3-8 days later (60-70%)

Monochorionic twins

•8-12 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 twins

Multiple pregnancy

Diagnosis

Patient profile:• Etiological factors: – positive past history and family history specially

maternal, race, age– Assisted reproductive technology

• Early pregnancy:– Hyperemesis, excessive weight gain– minor complications of pregnancy such as backache,

edema, varicose veins, hemorrhoids, striae, etc

Physical signs

• General:– Pallor, weight gain, excessive pedal edema/ varicose veins– Pregnancy Induced Hypertension(PIH) and Pre-eclampsia

(5-10times more)

• Abdominal:– Size > Date especially in midpregnancy– Multiple fetal parts– Auscultation of FHS:– 2 different recordings by 2 observers and a difference > 10

bpm

Differential diagnosis

• Elevation of the uterus by a distended bladder• Inaccurate menstrual history• Hydramnios• Hydatidiform mole• Uterine fibroids• A closely attached adnexal mass• Fetal macrosomia (late in pregnancy)

Ultrasonography

• Detect multifetal gestation 99% before 26 weeks• Confirm fetal number [ 2 sacs or 2fetal heads

in 2 perpendicular planes]• Diagnose type and presentation and position

and relation to each other• Exclude congenital abnormalities/ conjoint twin

Maternal complications

• Symptoms – hyperemesis, aches and pains of pregnancy worsen

• Hypertensive disease of pregnancy• Preterm delivery• Premature rupture of membranes• Polyhydramnios• Placenta praevia• Malpresentation• Delivery complications (operative delivery, placental

abruption, cord accidents)• Postpartum hemorrhage, depression

Fetal complications

• Spontaneous early pregnancy loss• Prematurity • Intra-uterine growth restriction• Cerebral palsy - related to gestational age, 3

times in twins, > 10 times in triplets• Intrapartum trauma• Monochorionic twins – specific complications

Antenatal care

• Routine booking investigationsFolic acid supplementation

anemia – 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 delivery•Reliable intravenous access•Cardiotocograph with dual monitoring capability•Portable ultrasound scanner•Delivery bed with lithotomy stirrups•Obstetric forceps or vacuum apparatus• active management of third stage: Uterotonics•Immediate availability of blood•Facilities and staff for emergency cesarean section

Monochorionic Monoamniotic twins

•3 - 12 x perinatal mortality•10 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