Placental Adhesive Disorders

Placental adhesive disorders, or abnormal placental, describes abnormal attachment of the placenta to the uterine wall. PAD:

Epidemiology and Risk Factors

Occurs in 1 in 500 pregnancies.

Major risk factors:

  • Placenta praevia
  • Previous caesarian section
    ↑ Risk:
    • 0: 2%
    • 1: 16%
    • 2: 24%
    • 3: 30%
  • Placenta praevia AND previous caesarian section
    Multiplicative risk: 40% of women with praevia and three previous caesarians will have placental adhesive disorder.
  • Smoking
  • Uterine trauma
    • Multiple curettes
      Asherman’s syndrome describes intrauterine adhesions occuring following uterine surgery.

Pathophysiology

Placenta:

  • Invades deep into the uterine wall
  • Does not separate from the uterus as it contracts
    Placental vessels remaing wide-open and continue to haemorrhage.

Clinical Manifestations

Diagnosis is difficult, and investigations usualy proceed based on risk factors.

Investigations

Diagnosis may be made on:

  • Ultrasound
    • Second or third trimester
    • Not reliable
    • Significant inter-observer differences
  • MRI
    • Greater sensitivity and specificity
  • Cystoscopy
    • Not usually performed as diagnostic test
    • Diagnosis of percreta may be made on cystoscopy performed for insertion of JJ stents prior to caesarian

Management

Antenatal diagnosis facilitates adequate preparation:

  • Patient counselling
    • Liklihood of hysterectomy
      May include plan for caesarian-hysterectomy.
  • Elective delivery
    • Tertiary obstetric centre
      • Personnel availability
        Senior:
        • Obstetric
        • Paediatric
        • Haematology
        • Intensive care
      • Use of cell salvage
      • Blood bank availability
    • Ureteric stenting
      If percreta.
    • Interventional radiology
      For:
      • Embolisation
      • Pre-emptive placement of balloon catheters to reduce haemorrhage

Surgical management options:

  • Caesarian hysterectomy
    Uterus removed with placenta in-situ.
  • Caesarian with uterine preservation
    One-third will still require hysterectomy due to bleeding, which may be delayed up to 4 week. Four major techniques:
    • Extirpative technique
      Manual removal of placenta.
    • Expectant management
      Placenta is left in situ.
      • ↓ risk of massive obstetric haemorrhage and placenta is removed from uterus
      • Preserves fertility
      • Placenta will necrose and ideally progressively detach itself
        Risk of sepsis or failure (and massive haemorrhage).
    • Conservative surgery
      Placenta accreta area is removed.
    • Triple-P
      Acceta is resected and then sutured.

Anaesthetic Considerations

General considerations for caesarian section, as well as considerations for general or regional techniques, are also critical.

  • C
    • Ensure 2× wide-bore IVs
    • Invasive arterial monitoring
  • D
    • Anaesthetic technique
      Either GA or neuraxial can be performed safely. A technique that the provider and system are comfortable with is appropriate.
      • Primary GA
        • Attendant risks of GA caesarian
        • Foetal effects of general anaesthetic agents
          Time to delivery often prolonged, and may be over an hour.
      • Primary neuraxial
        • Planned conversion to GA following delivery is reasonable in the setting of:
          • Hysterectomy
          • Massive PPH
          • Large volume resuscitation
          • Acidosis
  • H
    • Cross-match blood prior
  • O
    • Avoid oxytocin
      Placental separation is to be avoided in many surgical techniques.

Complications

  • Haemorrhage
  • Hysterectomy
  • Death

References

  1. Walfish M, Neuman A, Wlody D. Maternal haemorrhage. Br J Anaesth. 2009 Dec 1;103(suppl_1):i47–56.
  2. Sentilhes L, Kayem G, Chandraharan E, Palacios‐Jaraquemada J, Jauniaux E. FIGO consensus guidelines on placenta accreta spectrum disorders: Conservative management. International Journal of Gynecology & Obstetrics. 2018;140(3):291–8.
  3. Bowman ZS, Eller AG, Bardsley TR, Greene T, Varner MW, Silver RM. Risk Factors for Placenta Accreta: A Large Prospective Cohort. Amer J Perinatol. 2014 Oct;31(9):799–804.
  4. RANZCOG. Placental Accreta. 2014.