Multiple gestation management

Basics & Diagnosis - Two for One Deal

• Types:
  • Dizygotic (Fraternal): 2 eggs, 2 sperm. Always dichorionic, diamniotic (Di-Di).
  • Monozygotic (Identical): 1 egg, 1 sperm. Chorionicity depends on timing of division.
• Diagnosis: Ultrasound is key.
  • Confirms number of fetuses.
  • Determines chorionicity & amnionicity in 1st trimester.
    • Di-Di: Twin peak / Lambda (λ) sign.
    • Monochorionic-Diamniotic (Mo-Di): T-sign.
    • Monochorionic-Monoamniotic (Mo-Mo): No separating membrane.

⭐ Determining chorionicity is the single most important factor in managing multiple gestations, as it predicts the risk of complications like Twin-Twin Transfusion Syndrome (TTTS).

Maternal Risks - More Than a Handful

• Systemic Overload: Nearly all pregnancy complications are more frequent and severe.
• Preeclampsia: Risk is 2-3x higher. Monitor BP and proteinuria closely.
• Gestational Diabetes (GDM): Increased placental mass ↑ human placental lactogen (hPL), leading to insulin resistance.
• Anemia: Exaggerated hemodilution. Requires higher iron/folate supplementation.
• Hemorrhage:
  • Antepartum: ↑ risk of placenta previa & abruption.
  • Postpartum (PPH): High risk from uterine atony due to overdistension.
• Preterm Labor: The single most common complication.

⭐ Uterine atony from overdistension is the leading cause of Postpartum Hemorrhage (PPH) in multiple gestation. Be prepared for active management of the third stage of labor.

Fetal Complications - Wombmate Woes

• Universal Risks: Increased for all multiple gestations.

  • Preterm birth (< 37 wks) & Low Birth Weight (LBW)
  • Intrauterine Growth Restriction (IUGR)
  • Congenital anomalies (2x baseline risk)

• Monochorionic (MC) Syndromes: Due to placental vascular anastomoses.

  • Twin-Twin Transfusion (TTTS): Unbalanced blood flow.
    • Donor: Anemic, oligohydramnios ("stuck" twin).
    • Recipient: Polycythemic, polyhydramnios, hydrops.
  • Twin Anemia-Polycythemia Sequence (TAPS): Slow flow causing large hemoglobin difference without fluid discrepancy.
  • Selective IUGR (sIUGR): Unequal placental sharing → one twin <10th percentile.
  • Twin Reversed Arterial Perfusion (TRAP): Acardiac twin perfused by pump twin; high mortality (>50%) for pump twin.

⭐ TTTS Diagnosis: Requires monochorionic gestation + oligohydramnios (max vertical pocket [MVP] < 2 cm) in the donor's sac and polyhydramnios (MVP > 8 cm) in the recipient's sac.

Surveillance & Delivery - The Grand Exit

• Antepartum Surveillance:
  • Serial growth US: q 4-6 wks (Di/Di), q 2 wks (Mo/Di & Mo/Mo).
  • Antepartum testing (NST, BPP) weekly from 32-34 wks.
• Delivery Mode:
  • Vaginal: Attempt if Twin A is vertex.
  • Cesarean: Required for non-vertex Twin A, most Mo/Mo twins, and other standard OB indications.

⭐ Monochorionic-monoamniotic (Mo/Mo) twins require inpatient admission around 24-28 weeks for intensive fetal surveillance due to the high risk of cord entanglement, with a planned C-section at 32-34 weeks.

High-Yield Points - ⚡ Biggest Takeaways

• Chorionicity is the single most important prognostic factor; monochorionic twins are at unique risk for Twin-to-Twin Transfusion Syndrome (TTTS).
• Early ultrasound is critical to establish chorionicity and amnionicity, which dictates the entire surveillance schedule.
• Expect a higher incidence of maternal complications, especially pre-eclampsia, gestational diabetes, and anemia.
• Preterm labor is the most common complication; have a low threshold to administer antenatal corticosteroids.
• Delivery is planned earlier than singletons, with timing based on chorionicity and complications (32-38 weeks).