Irregular collagen in uterine scars associated with placenta accreta development

Irregular collagen in uterine scars associated with placenta accreta development

Placenta accreta spectrum (PAS) used to be a rare pregnancy disorder, but today it affects around 14,000 pregnancies per year and is a leading cause of maternal death. But why this happens is still not fully understood. Placenta accreta occurs when the placenta grows too deep into the uterine wall and fails to separate after birth, often leading to life-threatening bleeding and the need for a hysterectomy.

The strongest and most common risk factor is previous cesarean delivery, as scars from previous cesarean deliveries can change the way the placenta attaches in future pregnancies. New research led by UCLA Health suggests that the way this scar tissue heals could be key to better understanding how PAS develops, who is at risk, and why the placenta attaches abnormally.

“Our results show that the main problem with placenta accreta is not the abnormal growth of the placenta, but the way uterine scars alter the structure and organization of collagen in the uterus, increasing the risk of delivery,” said Dr. of the study.

The study, published in theAmerican Journal of Obstetrics and Gynecologyused surgical samples, a mouse model, and a lab-grown accreta-in-a-dish system to study how collagen structure, when it becomes tangled or irregular instead of neatly aligned, contributes to abnormal placental attachment. Using advanced 3D imaging, researchers have found that tangled or irregular collagen on old uterine scars breaks the normal boundary between the uterus and placenta, creating a permissive environment for abnormal placental attachment and creating a high-risk delivery.

Researchers collected samples from 13 patients with PAS and 10 with accreta risk factors but without PAS, sampling tissue from where the placenta was stuck and where it wasn't. Their results showed that persistent inflammation and immune cells called macrographs interfere with normal scar remodeling, leading to abnormal collagen architecture that promotes abnormal placental attachment.

Not all scars heal the same way. This work helps explain why some patients develop placenta accreta after a cesarean section but others do not, and suggests new ways we can detect the risk earlier, before pregnancy or early in pregnancy.”

Yalda Afshar, MD, associate professor of obstetrics and gynecology, division of maternal-fetal medicine, David Geffen School of Medicine, UCLA

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