Abnormal Placentation

During pregnancy, the placenta develops in the uterus and attaches to the uterine wall. In some rare cases, the placenta can attach deeply into the uterus and/or invade through it to surrounding organs. Known as abnormal placentation, this condition can make it difficult to remove the placenta from the uterus after birth — presenting a serious health risk for the mother.

The different types of abnormal placentation include:

Placenta previa

Placenta previa occurs when the placenta sits in the lower part of the uterus and covers part or all of the cervix

Morbidly adherent placenta (MAP)

Three specific disorders fall under this classification; the placenta's placement and depth of invasion into the uterine wall will determine the diagnosis

• Placenta accreta: When the placenta grows abnormally attached to the muscle layer of the uterus (the myometrium)
• Placenta increta: When the placenta invades partially through the muscle layer of the uterus (the myometrium)
• Placenta percreta: When the placenta invades through the muscle layer of the uterus (the myometrium), the outer layer of the uterus (the serosa) and may attach to surrounding organs, such as the bladder

If not diagnosed and managed, abnormal placentation can cause serious complications in the third trimester of pregnancy or after delivery. An early diagnosis and management plan can minimize risks and complications during the pregnancy and improve outcomes for mother and baby.

Placenta accreta occurs in approximately one out of 533 pregnancies.

Although there is no known cause, a clear association exists between abnormal placentation and certain surgeries, procedures and other risk factors, including:

• Prior cesarean section (C-section)
• Dilation and curettage (D&C)
• Prior uterine surgery
• Endometrial ablation
• Giving birth to multiples (twins, triplets or more)
• Advanced maternal age (35 and up)

Some studies indicate a correlation between the rise in the number of C-sections in recent history and the increase in abnormal placentation.

Our experts at the University of Chicago Medicine are dedicated to achieving the best possible outcome in each delivery and in postpartum care. We will work with your current obstetrician to create an individualized surgical delivery plan for you, designed to minimize complications.

We have established and continue to refine specialized strategies for managing the most complex cases of these high-risk placental disorders.

We will perform an ultrasound to evaluate your baby and the placenta, followed by a consultation with a maternal-fetal medicine specialist. Based on the ultrasound results, some patients may need an MRI for further evaluation. If any follow up appointments are needed, we will schedule them for you at the end of your visit.