What is Placenta Accreta?

Placenta accreta is a rare condition that occurs when the placenta attaches itself too firmly to the wall of the uterus and cannot be removed after birth. Heavy bleeding often occurs after the delivery of the baby. This commonly requires surgery to stem the bleeding and fully remove the placenta, and in severe forms can often lead to a hysterectomy or be fatal.

Placenta accreta affects approximately 1 in 2,500 pregnancies. The most common form of placenta accreta is an invasion of the myometrium which does not penetrate the entire thickness of the muscle. This form of the condition accounts for around 75-78% of all cases, and has no name other than placenta accreta.

There are two further variants of the condition that are known by specific names and are defined by the depth of their attachment to uterine wall. Placenta increta occurs when the placenta further extends into the myometrium and happens in around 17% of all cases. Placenta percreta, the worst form of the condition and occurring in 5-7% of cases, is when the placenta penetrates the entire myometrium to the uterine serosa (invades through entire uterine wall). This variant can lead to the placenta attaching to other organs such as the rectum or bladder.

A diagram illustrating the different types of placenta accreta.