Risk of Placenta Accreta After Myomectomy with Endometrial Cavity Entry

Understanding the Mechanism

The American College of Obstetricians and Gynecologists explains that placenta accreta spectrum develops when defects in the endometrial-myometrial interface lead to failure of normal decidualization in areas of uterine scarring, allowing abnormally deep placental anchoring and trophoblast infiltration 1, 2, 3, 4
When the endometrial cavity is entered during myomectomy, this creates precisely the type of disruption within the uterine cavity that damages the endometrial-myometrial interface, affecting scar tissue development and increasing the likelihood of placenta accreta 1, 2

Prior uterine surgeries are explicitly listed as established risk factors for placenta accreta spectrum by the American College of Obstetricians and Gynecologists, alongside cesarean delivery, curettage, and Asherman syndrome 1, 2, 3, 4
If placenta previa develops overlying the myomectomy scar, the risk escalates dramatically - similar to the well-established cesarean scar-previa combination that creates 11-67% accreta risk depending on the number of prior surgeries 1, 2, 3

Gray-scale ultrasound should be the first-line imaging modality, looking for loss of the normal hypoechoic retroplacental zone, placental lacunae, thinning of the uterine serosa-bladder interface, and abnormal placental vascularity 5

The absolute magnitude of increased risk after myomectomy is not as precisely quantified as it is for cesarean delivery, where systematic reviews show 0.3% risk after one cesarean increasing to 6.74% after five cesareans 1, 2, 3
Entry into the endometrial cavity is particularly significant because it creates a full-thickness defect similar to cesarean delivery, rather than a subserosal defect that would not involve the decidual layer 6