Multiple Pregnancy

Multiple Pregnancy

Key Facts

• About 1 in 80 pregnancies at term
• incidence is rising with increasing maternal age and assisted conception.
• The second twin is at greater risk of intrapartum compromise.
• Vaginal birth is usually safely achievable where the presenting twin is in a cephalic vertex presentation.
• Caesarean section performed If the first twin presents by the breech or transverse.

Associated Complications

• abnormal fetal growth
• malpresentation
• CTG abnormalities
• cord prolapse
• need for emergency caesarean section in labour
• PPH.

Twins in Different Positions

Scenarios

Delivery of Twins

Steps

• Vaginal birth if the first twin is in a cephalic (vertex) presentation.
• Caesarean section performed If the first twin presents by the breech or transverse.(not cephalic)
• Delivery of the 2nd twin:
• After the delivery of the 1st twin:
  • ✔ clamp the cord.
  • ✔ Determine the position of the 2nd twin.
  • ✔ Bring the nearest pole (breech or cephalic).
  • ✔ Do ARM & give oxytocin iv.

Shoulder Presentation

Causes and Management

• Shoulder presentation occurs as the result of a transverse or oblique lie of the fetus.
• Causes include:
  • placenta praevia.
  • high parity.
  • pelvic tumour.
  • uterine anomaly.
• Delivery should be by caesarean section.
• Delay:
  • cord prolapse.
  • uterine rupture.

Multiple Pregnancy

DIZYGOTIC TWINS

• Most common represents 2/3 of cases.
• Fertilization of more than one egg by more than one sperm.
• Non identical may be of different sex.
• Two chorion and two amnion.
• Placenta may be separate or fused.

Factors Affecting Dizygotic Twins Incidence

Factors

• Induction of ovulation, 10% with clomide and 30% with gonadotrophins.
• Increase maternal age? Due to increase gonadotrophins production.
• Increases with parity.
• Heredity usually on maternal side.
• Race; Nigeria 1:22 North America 1:90.

MONOZYGOTIC TWINS

• Constant incidence of 1:250 births.
• Not affected by heredity.
• Not related to induction of ovulation.
• Constitutes 1/3 of twins.

Identical (Monozygotic) Twins vs Fraternal (Dizygotic) Twins

Identical (Monozygotic) Twins

• Fertilized egg
• 2-cell stage
• Single zygote divides in two

Fraternal (Dizygotic) Twins

• Two separate fertilized eggs
• Two separate zygotes

Twinning Cleavage Stages

Stages

• 0-4 days
  • 2-cell stage
  • Cleavage results in:
    • Dichorionic diamniotic with Fused placenta or Separate placenta
• 4-8 days
  • Morula
  • Cleavage results in:
    • Monochorionic diamniotic
• 8-12 days
  • Blastocyst
    • Components:
      • Chorionic cavity
      • Amniotic cavity
      • Formed embryonic disc
  • Cleavage results in:
    • Monochorionic monoamniotic
• > 13 days
  • Cleavage results in:
    • Monochorionic monoamniotic conjoined twins

Monochorionic Twins

• 70% are diamniotic monochorionic.
• 30% are diamniotic dichorionic

Diagnosis of Zygosity

Determining Zygosity

• Different sex indicates dizygotic twins.
• Separate placenta indicate dizygotic twins.

Determination of Zygosity After Birth

• By examination of the MEMBRANE, PLACENTA, SEX, BLOOD GROUP.
• Examination of the newborn DNA and HLA may be needed in few cases.

Complications of Multiple Pregnancy

Maternal Complications

• Anemia
• Hydramnios
• Preeclampsia
• Preterm labour
• Postpartum hemorrhage
• Cesarean delivery

Fetal Complications

• Malpresentation
• Placenta previa
• Abruptio placenta
• Premature rupture of the membranes
• Prematurity
• Umbilical cord prolapse
• Intrauterine growth restriction
• Congenital anomalies
• TTTS

Monochorionic Complications

TWIN-TWIN Transfusion Syndrome (TTTS)

• Results from vascular anastomoses between twins vessels at the placenta.
• Usually arterial (donor) venous (recipient).
• Occurs in 10% of monochorionic twins.
• Chronic shunt occurs, the donor bleeds into the recipient so one is pale with oligohydramnios while the other is polycythemia with hydramnios.
• If not treated death occurs in 80-100% of cases.

Possible Methods of Treatment for TTTS

• Repeated amniocentesis from recipient.
• Indomethacin.
• Fetoscopy and laser ablation of communicating vessels.

Severity Staging System for TTTSY

1. The bladder is still visible in the donor twin.
2. The bladder is no longer visible in the donor.
3. Critically abnormal Doppler in either twin: absent-reverse diastolic flow in the donor or recipient umbilical artery and/or absent/reverse flow in the ductus venosus or pulsatile flow in the umbilical vein of the recipient.
4. Hydrops in either fetus.
5. Demise of one or both twins.

All Doppler measurements need to be done. A case cannot be staged unless umbilical artery, umbilical vein, and ductus venosus Dopplers have been performed.

Other Complications in Monochorionic Twins

• Congenital malformation. Twice that of singleton.
• Umbilical cord anomalies. In 3 - 4 %.
• Conjoined twins. Rare 1:70000 deliveries. The majority are thoracopagus.
• PNMR of monochorionic is 5 times that of dichorionic twins (120 vs 24/1000 births)

Diagnosis

• History
• Examination
• Ultrasound

Antenatal Care

Fetal Surveillance

• Monthly USS from 24 weeks to assess fetal growth and weight.
• A discordant weight difference of >25% is abnormal (IUGR).
• Weekly CTG from 36 weeks.

Methods of Delivery

Vertex-Vertex (50%)

• Vaginal delivery

Vertex-Breech (20%)

• Vaginal delivery by senior

Breech-Vertex (20%)

• CS is safer to avoid interlocking twins.

Breech-Breech (10%)

• Usually CS
• For Monochorionic twins
• CS

Perinatal Outcome Complications

• Perinatal mortality is 5 times more than singleton.
• RDS 50% more
• Incidence of stillbirth is twice that of singleton
• Anomaly
• Cerebral hemorrhage and asphyxia
• Cerebral palsy 4 times that of singleton.

Higher-Order Multiple Pregnancies

Triplets Quadruplets