What causes placenta accreta?

Instead of separating normally after birth, the placenta may remain firmly attached. Placenta accreta spectrum describes differing depths of attachment, including growth into the uterine muscle or through its outer surface.

A previous caesarean birth or other operation involving the uterus can leave a scar where placental tissue later implants. Placenta lying low in the uterus or covering the cervix is particularly relevant when a uterine scar is also present.

Previous procedures inside the uterus and some uterine abnormalities may also be associated. However, the condition can occur without a recognised factor, and having a scar does not mean placenta accreta will develop.

Placenta accreta is often suspected on ultrasound, with additional imaging considered when the attachment needs clearer mapping. If it is suspected, care is usually coordinated by an experienced obstetric team with anaesthesia, blood bank and surgical support available.

The team will discuss where and how birth should take place and how bleeding would be managed. A planned caesarean birth may be recommended. In some cases, hysterectomy is the safest way to control bleeding because trying to detach an embedded placenta can cause major blood loss. The precise plan depends on imaging, placental position, depth of invasion, your health and your wishes.

Placenta accreta may cause no symptoms before birth, so attendance at planned scans and appointments matters. Follow any specific instructions from your specialist maternity team about activity, travel and where to go if symptoms begin.

Seek immediate maternity assessment for any vaginal bleeding, contractions, leaking fluid, new severe abdominal pain, dizziness, faintness or reduced fetal movement. Call emergency services for heavy bleeding, collapse, breathing difficulty or severe weakness.

Ask what the scans show about placental location and depth, who will be present for delivery, how bleeding and transfusion needs are prepared for, and whether hysterectomy is anticipated. You may also want to discuss fertility implications, anaesthesia, recovery, neonatal support and the plan if labour or bleeding starts before the scheduled birth.