Placenta increta

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. 

Epidemiology

The estimated incidence is increasing (likely related to the increased practice of caesarean sections), probably ~1 in 50,000 pregnancies.

Risk factors 

• prior caesarean section
• placenta praevia
• advanced maternal age
• uterine anomalies
• intrauterine adhesion bands
• previous surgery

Pathology

In placenta increta, chorionic villi invade well into the myometrium but not through the entire wall.

Radiographic features

Ultrasound

As with the less severe placenta accreta, there can be focal obliteration of the hypoechoic retroplacental zone ⁴.