Placenta increta is an intermediate level in the spectrum of abnormal placental villous implantation and accounts for ~20% of such cases. The placental villi extend beyond the confines of the endometrium and invade the myometrium.
The estimated incidence is increasing (likely related to the increased practice of cesarean sections), probably ~1 in 50,000 pregnancies.
- prior cesarean section
- placenta previa
- advanced maternal age
- uterine anomalies
- intrauterine adhesion bands
- previous surgery
In placenta increta, chorionic villi invade well into the myometrium but not through the entire wall.
As with the less severe placenta accreta, there can be focal obliteration of the retroplacental hypoechoic zone .