Obstetrics Marrow Pg 455-464 (Obstetrics Complications)

Twin Pregnancy: Part 1

• Dizygotic twins form when two ova are fertilized by two different sperms, forming two separate zygotes.
• Monozygotic twins form when a single ovum is fertilized by a single sperm, forming a single zygote that divides into two separate zygotes.
• The incidence of dizygotic twins varies geographically, with the highest incidence in Nigeria (1 in 20) and the lowest in Japan (1 in 200).
• The incidence of monozygotic twins is relatively uniform throughout the world (1 in approximately 250).
• Hellin's Rule states that if the incidence of twins in a country is 1 in 80, then the incidence of triplets is 1 in 802 and the incidence of quadruplets is 1 in 803.

Chorionicity & Amnionicity

• Dizygotic twins: Always dichorionic and diamniotic (DCDA)
• Monozygotic twins: Chorionicity and amnionicity depend on the time of division of the zygote.

Monozygotic Twins: Chorionicity & Amnionicity

• < 4 days: Dichorionic Diamniotic (DCDA)
• 4-8 days: Monochorionic Diamniotic (MCDA)
• 8-12 days: Monochorionic Monoamniotic (MCMA)
• ≥ 14 days: Conjoined twins (MCMA)

Types of twins based on chorion and amnion formation:

• Dichorionic Diamniotic (DCDA): Two separate chorions and two separate amniotic sacs.
• Monochorionic Diamniotic (MCDA): One chorion and two amniotic sacs.
• Monochorionic Monoamniotic (MCMA): One chorion and one amniotic sac.

Complications:

• Monochorionic Monoamniotic (MCMA): Cord entanglement, Sudden Intrauterine death (IUD) of both twins.
• Management of MCMA: Corticosteroid for lung maturity, Cesarean section at 32-34 weeks.

Prognosis:

• DCDA (Dizygotic twins): Better prognosis.
• Monozygotic twins: MCDA: Also better prognosis.
• Monochorionic: Bad prognosis.
• Dichorionic: Better prognosis.

Determination of chorionicity:

• IOC: USG (TVS)
• Timing: 10 weeks-14 weeks/1st trimester.

DCDA vs MCDA vs MCMA

Conjoined Twins

• A complication of monoamniotic twins, result from the complete or partial fusion of identical twins.
• Types:
  • Paraphagus: Joined at lower abdomen & pelvis.
  • Thoracophagus: Joined at thorax.
  • Rachiphagus: Joined at vertebral column.
  • Craniophagus: Joined at the head.

USG in Twin Pregnancy

• Significance:
  • Assess gestational age: Earliest 7 weeks, Best 10 weeks.
  • Determine chorionicity.
  • ↑ Nuchal translucency (NT): Suspect twin-to-twin transfusion syndrome.

Markers of Dichorionicity on USG:

• ≥ 4 membranes between twins.
• ≥ 2 mm thickness of membranes.
• Different sexes on USG.
• 2 placenta (+).
• Twin peak sign (+)

Superfecundation vs Superfetation

• Superfecundation: Both ova released in the same cycle, fertilized at different times by different acts of coitus.
• Superfetation: 2 ova released and fertilized in different cycles. Not seen in humans.

Risk Factors for Twin Pregnancy:

• Dizygotic Twins:
  • Geographical distribution.
  • Increased maternal age.
  • Increased parity.
  • Maternal family history of twins.
  • IVF.
  • Ovulation induction drugs (Clomiphene citrate, hMG).

Fetal Membranes

Miscellaneous

• D/D for Bleeding Female ≥28 Weeks:

  • APH:
    • Abruptio placenta
    • Placenta previa
    • Vasa previa
    • Uterine rupture
    • Preterm labor

• Labour vs Abruptio:

• ARM in Abruptio:

  • Liquor is dark red in color.
  • Accelerates labor process.
  • Increased bleeding.

• Abruptio vs Ruptured Uterus:

Placenta Accreta Spectrum (PAS)

• Villi of placenta attaches to/infiltrates the myometrium.
• Previously known as: Morbidly adherent placenta.

FIGO CLASSIFICATION OF PAS

Etiopathogenesis of PAS

• 1. Absent decidua basalis/defective decidualization.
  • Nitabuch's layer: Layer of fibrinoid degeneration between trophoblast and decidua basalis. Function: Limits the penetration of trophoblastic villi into decidua. Absence → Deeper penetration of blastocyst.
• 2. Absent Nitabuch's layer.
• 3. Hyper-invasiveness of cytotrophoblast.

Management of Abruptio Placenta

• Emergency Conditions:

  • Maternal vitals unstable, Fetal distress, DIC, Acute Kidney injury.
  • Action: Immediate C-section.

• Non-Emergency Conditions (Normal Fetal Heart Sounds):

  • Maternal vitals stable, No DIC.
  • Action: Vaginal delivery.

• Gestational Age:

  • ≥ 34 weeks: Induction of labor.
  • < 34 weeks: Expectant management.

Disseminated Intravascular Coagulation (DIC)

• Aka Consumptive coagulopathy.

• Obstetric Causes:

  • Abruptio placenta
  • Amniotic fluid embolism
  • Septic abortion
  • Acute fatty liver of pregnancy

• Management:

  • Cryoprecipitate
  • Fresh frozen plasma (FFP)

• In abruptio + DIC:

  • Manage DIC
  • C-section.

• Additional Considerations:

  • Intrauterine death (for ≥ 4 weeks)
  • Rarely in severe Preeclampsia/Eclampsia/HELLP syndrome
  • Blood Transfusion

Management of Placenta Accreta Spectrum

• Antenatally Detected PAS:

  • Management of choice: Elective C-section between 34-35 weeks + 6/7 days, followed by hysterectomy (with placenta in-situ).
  • General anesthesia: Preferred.
  • Classical C-section: Done to avoid the placental site.
  • No attempt to separate/deliver the placenta: Uterine incision closed prior to hysterectomy to avoid bleeding.
  • Pre-op ureteric catheterization: Helps in ureteric identification (if bladder invasion present).
  • Pre-op internal iliac artery catheterization: Decreases blood flow to the pelvis, reducing bleeding. Not recommended by ACOG.

• Postnatally Detected PAS:

  • Clinical features:

    • Intractable postpartum hemorrhage (PPH).
    • Placenta cannot be separated.
    • Hematuria (plus/minus).

  • Management:

    • Emergency hysterectomy.

  • If fertility is desired:

    • Placenta left in situ, with cord ligated close to the placental insertion, followed by hysterotomy incision closure and compression sutures/ tamponade packing to control bleeding.

  • Investigations : Serial ultrasound (USG) and Magnetic Resonance Imaging (MRI).

  • Serial β-hCG: (No role of methotrexate injection).

• Prognosis: 20% will require hysterectomy ultimately.

Risk Factors for PAS:

• 1.Placenta previa (Anterior) in present pregnancy.
  • Previous surgeries:
    • Previous C-section (Risk ↑ with number of C-sections).
    • Myomectomy.
    • Curettage.
    • Endometrial ablation.
• 2.Previous history of PAS.
• 3.Risk factors of placenta previa.

Investigations for PAS

• Markers (Not routinely done):
  • Maternal serum AFP ≥ 2.5 moM { ↑risk of PAS }
  • Maternal serum hCG ≥ 2.5 moM { ↑risk of PAS }
• Screening: Anomaly scan (characteristic findings + in T2).
• Definitive Diagnosis: USG with color Doppler (10c) at 28 weeks.

Signs of PAS on USG

• 1.Large placental lacunae/placental lakes (sonolucent areas):

  • Moth-eaten appearance.
  • Color Doppler: Increased vascularity in lacunae.

• 2.Thinning of retroplacental myometrium: (Distance b/w serosa & myometrium < 1 mm)

Explore the fascinating world of twin pregnancies in this quiz, focusing on the formation, incidence, and classification of dizygotic and monozygotic twins. Learn about the geographical variations in twin occurrences and understand the principles of chorionicity and amnionicity. Test your knowledge about twin pregnancies and their unique characteristics.