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Placenta Previa 


  • Placenta previa

    • Definition : presence of placental tissue that extends over the internal cervical os

    • Estimated to affect 1/200 pregnancies.

    • Known placenta previa necessitates cesarean birth somewhere between 36 to 37+6 gestational age

  • Placenta accreta spectrum includes 3 sub-types.  The most important risk factor for developing these is placenta previa after a prior cesarean delivery

    • Accreta: placenta adhered to myometrium without invasion through uterine muscle 

    • Increta: invasion of myometrium 

    • Percreta:  invasion of uterine serosa and other structure


  • Pregnancy considerations (difficult intubation, aspiration, quick desaturation, aortocaval compression, 2 patients)

  • Increased risk of antepartum hemorrhage and the need for resuscitation and possibly emergency delivery

  • Increased risk of intra-operative blood loss even without pre-operative bleeding due to injury by obstetrician to an anteriorly located placenta during uterine incision and low uterine tone of the lower uterine segment implantation site



  • Chestnut's Obstetric Anesthesia, 6th Edition.  Chapter 37: Anterpartum and Postpartum Hemorrhage.

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