Fact-sheet: Placenta accreta

Updated on 04/19/2018 at 3:52 PM

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Definition

Invasion of the myometrium by chorionic villi resulting in:

an absence of decidualized endometrium interposed between the placenta and the myometrium
with loss of the normal cleavage plane, associated with excessive utero-placental vascular communication
and with a risk of incomplete delivery and severe hemorrhage

Systematic screening during second- and third-trimester Doppler Ultrasounds, with description of placental location.

Presence of lacunae with pulsatile flow.

Placenta accreta: presence of lacunae, an essential sign reflecting utero-placental neovascularization

Accreta implantation: penetration into the superficial layer of the myometrium

Increta implantation: penetration into the thickness of the myometrium

Percreta implantation: penetration through the full thickness of the myometrium with possible pelvic extension (especially the bladder)

Normal placenta

On ultrasound: hyperechoic relative to the myometrium in the 2nd trimester, heterogeneity in the 3rd trimester related to physiologic placental maturation (calcifications, lakes),
Hyperechoic interface with the myometrium, posterior to the placenta, corresponding to the decidualized endometrium
On MRI: T2 hyperintense relative to the myometrium
T2-hypointense basal line
Intermediate T1 signal, more intense than the myometrium