Obstetric complications

Question 1

PAS - definitions

Answer 1

• Accreta = abnormally deep invasion, only to the surface of the muscle layer of the uterus (decidua basalis layer) i.e. through decidua and attached to the myometrium but not into the myometrium
• Increta = penetrates into (but not through) the myometrium i.e. not involving the serosa
• Percreta = penetrates through full thickness of the myometrium up to the serosal surface +/- beyond the serosa to surrounding organs (i.e. +/- invasion into the bladder)

Question 2

PAS - risk factors

Answer 2

• Previous CS (risk increases with no. of CS)
  
  • 1x CS and placenta praevia = 10%
  • 2x CS and placenta praevia = 40%
  • 3x CS and placenta praevia = 61%
  • 4-5x CS and placenta praevia = 67%
• ⁠Placenta praevia
• ⁠Older maternal age
• ⁠Multiparity
• ⁠Not in RANZCOG guideline but -> short CS – conception interval considered a RF

(4 independent RFs reported in Aus/NZ)

Question 3

PAS - imaging

Answer 3

• US is considered 1st line for assessment + diagnosis of PAS
• ⁠US has comparable diagnostic accuracy and is more widely available than MRI
• ⁠3 main modalities can be used on US  greyscale, colour doppler, and 3D power doppler
  
  • Greyscale: ‘FLAB’ —> Focal exophytic mass, Loss of clear zone, Abnormal placental lacunae, Bladder wall interruption
  • Colour Doppler: ‘SUB-L’ —> Subplacental hypervascularity, Uterovesical hypervascularity, Bridging vessels, Lacunae feeder vessels
  • 3D power doppler: Hypervascularity (intraplacental)
• ⁠MRI may be a useful adjunct – esp. if diagnosis is uncertain, posterior placenta (more difficult to assess on US) or for other surgical planning reasons as preference by the unit. Note: no explicit indications for MRI have been identified/consensus agreement
• MRI features: ‘D-D-DUH’ —> Disruption (of uteroplacental zone), Disorganised (vasculature of the placenta), Dark Intraplacental Bands, Uterine Bulging, Heterogenous signal intensity

Question 4

PAS - management

Answer 4

GTG bundle of care (RANZCOG very similar recommendations)
* MDT involvement and pre-operative planning
* ⁠Consultant obstetrician planned/directly supervised delivery
* ⁠Consultant anaesthetist
* ⁠Blood / blood products available onsite
* ⁠Discussion/consent includes interventions eg. hysterectomy, leaving placenta in situ, cell salvage, interventional radiology
* ⁠Local availability of ICU bed
* ⁠* RANZCOG —> Routine use of IR is not recommended

Question 5

PAS - delivery

Answer 5

• Timing: varies in the literature (34-37 weeks), RWH/RCOG suggests 36 weeks with accreta
• ⁠RANZCOG guideline does not specify - “Timing of birth for women with suspected or confirmed PAS should be based on clinical grounds and the need to optimise fetal maturity.”
• Options at time of delivery (General):
  
  • Deliver baby and attempted delivery of placenta → associated with high likelihood of hysterectomy but not invariably; surgeon must be prepared to promptly perform hysterectomy and anaesthetist activate MTP
  • Delivery of baby via uterine incision distant from placenta, quick repair of uterus and en bloc hysterectomy
  • Delivery of baby via uterine incision distant from placenta, trimming of cord close to insertion site, full repair of uterus and conservative management (i.e. leave placenta in situ but don’t perform hysterectomy) → 2/3 will avoid hysterectomy, 1/3 will require hysterectomy