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Abnormal placentation

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aliasesPlacenta accreta

3 min read

Defective decidual layer of the placenta leading to abnormal attachment and separation during postpartum period

Epidemiology

Classification

  • Placenta accreta: chorionic villi attach to the myometrium (but do not invade or penetrate the myometrium) rather than the decidua basalis (up to 75% of cases)
  • Placenta increta: chorionic villi invade or penetrate into the myometrium (approx. 20% of cases)
  • Placenta percreta: chorionic villi penetrate the myometrium, penetrate the serosa, and in some cases, adjacent organs/structures (approx. 5% of cases)
    • Like bladder

Mnemonic

The types of abnormal placental attachment: Placenta Accreta “Attaches” to the myometrium, placenta Increta “Invades” the myometrium, and placenta Percreta “Perforates” the myometrium.

Pathophysiology

Risk factors

  • History of uterine surgery (e.g., endometrial ablation, hysteroscopic removal of intrauterine adhesions, dilatation, curettage)
  • Prior births by cesarean delivery
  • Placenta previa
  • Multiparity
  • Advanced maternal age

Clinical features

Diagnostics

  • Ultrasound
    • Thinning of uterine myometrial wall c
    • Placental lacunae (particularly irregularly shaped), giving the placenta a moth-eaten appearance
    • Disruption of the junction between the bladder wall and uterine serosa
    • Loss of clear space behind the placenta

Treatment

  • Emergency Stabilization (Active Hemorrhage / Unstable):

    1. Airway/Breathing/Circulation: Two large-bore IVs (16-18 gauge), rapid IVF resuscitation.
    2. Transfusion: Activate Massive Transfusion Protocol (MTP) if indicated (PRBCs : FFP : Platelets = 1:1:1).
    3. Continuous Monitoring: Maternal vitals and continuous FHR monitoring.
    4. Immediate Emergency Cesarean Delivery: If maternal hemodynamic instability, refractory hemorrhage, or non-reassuring fetal status, regardless of GA.

  • Placenta Previa (Hemodynamically Stable):

    1. Antenatal Care: Pelvic rest (strict avoidance of sexual intercourse, DVE, and tampon use); outpatient management only if stable with immediate hospital access.
    2. Delivery Timing: Planned Cesarean delivery at 36 0/7 to 37 6/7 weeks GA.
    3. Antenatal Corticosteroids (Betamethasone): If bleeding occurs <37 weeks GA or prior to scheduled early delivery.

  • Placenta Accreta Spectrum (Stable / Diagnosed Antenatally):

    1. Multidisciplinary Planning: Delivery at a tertiary center with MFM, Gyn-Onc, Uro, Interventional Radiology (IR), and blood bank.
    2. Delivery Timing: Planned delivery at 34 0/7 to 35 6/7 weeks GA (administer antenatal corticosteroids at 34 wks).
    3. Primary Surgical Intervention: Planned Cesarean Hysterectomy.
      • Do NOT attempt manual removal of the placenta (drastically increases maternal mortality and hemorrhagic shock).
      • Deliver fetus via hysterotomy avoiding the placenta, close uterine incision with placenta in situ, and proceed directly to hysterectomy.

  • Refractory Postpartum Hemorrhage / Fertility-Sparing Options:

    • Uterine artery embolization (IR).
    • Internal iliac (hypogastric) artery ligation.
    • Uterine compression sutures (e.g., B-Lynch) or intrauterine balloon tamponade (Bakri balloon) for low-grade focal adherent tissue.

Graph View

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