Why Is Placenta Accreta Now Considered a Spectrum Disorder?

Placenta accreta is the condition that results when the placenta abnormally grows into the wall of the uterus. This potentially serious problem can complicate your pregnancy and delivery. Just to confuse matters, researchers now define what was initially named placenta accreta as placenta accreta spectrum disorder or PAS disorder for short. A diagnosis of PAS can impact the care you receive during your pregnancy and the type of delivery you have. With a better understanding of PAS, provided below and with The Pulse’s helpful list of questions for your doctor, you can prepare to be an informed and empowered member of your pregnancy care team.

What Do We Know About Placenta Accreta Spectrum?

Think of PAS as the umbrella term for all of the various kinds of abnormal placental growth during pregnancy. Doctors and researchers switched to using the spectrum concept to better classify abnormal placental growth for more accurate research findings. The three main types of PAS are placenta accreta, placenta increta, and placenta percreta.

The number of women with PAS is directly related to rising cesarean rates worldwide. The more C-sections a woman has, the greater her risk for PAS. More than 90% of all women experiencing PAS also have placenta previa. In placenta previa, the placenta attaches lower in the uterus such that it either partially or entirely blocks the cervix. The combination of PAS and placenta previa can prove very dangerous for women and their babies, putting moms at risk for life-threatening bleeding at the time of their delivery.

We also know that women who have had other kinds of uterine surgeries but who have not been pregnant are at risk for PAS, even in their first pregnancy. Prior abortions, endometrial ablations, myomectomies, and surgery to repair uterine abnormalities all increase risk. Current research also shows that in vitro fertilization (IVF), especially with cryopreserved embryos, increases the risk for PAS between 4- to 13-fold.

Early Diagnosis Saves Lives

Modern obstetrics recommends moms with PAS deliver by scheduled C-section ahead of their expected delivery date, usually somewhere between 34-36 weeks. Unfortunately, recent population-based studies show that PAS remains undetected before delivery in half to two-thirds of PAS cases.

That is why the announcement of a new blood test for PAS is so exciting. Developed by an international team of researchers, this test can be performed during the first trimester, allowing for earlier referral for specialty care.  The NanoVelcro Chip technology can detect a type of placental cell associated with PAS in moms’ bloodstream.

Planned Cesarean Delivery To Reduce Risk of Hemorrhage and Preserve Fertility

Delivering by planned cesarean section at a tertiary-level care center with a multidisciplinary care team is the recommended plan for keeping you and your baby safe during delivery. However, the timing of when the delivery happens is individualized and must balance what is best for you (how great is your risk of hemorrhage) against what is best for your baby (how many weeks along in your pregnancy are you).

Preparations during pregnancy, such as treating any anemia you might have and monitoring your hemoglobin and iron levels, are recommended. If you start bleeding during pregnancy, your doctor may advise you to limit your physical activity or even hospitalize you before your scheduled cesarean section. The distance you live from a major hospital with maternal-fetal specialists, neonatologists, anesthesiologists, urologists, interventional radiologists, and blood bank may also determine your birth plan.

Most often, the safest way to avoid a hemorrhage at the time of the C-section is to remove the woman’s entire uterus (called a hysterectomy) with the placenta still attached. For women who wish to have more children, special surgical techniques can sometimes preserve their uterus, with or without removing the placenta at the time of your C-section. Unfortunately, there have not been enough studies to show whether a particular management technique is safer or more successful than another. If you know very strongly that you want to have more children, it is important that you discuss the various surgical and management options with your doctor(s) so that you can make an informed decision about your care.

What Questions To Ask Your Doctor

We all know that moment of panic in a doctor’s office. We receive a diagnosis or a treatment plan, and our brain starts to melt as we try to process. We leave the doctor’s office and then think of a laundry list of questions we wished we asked.

PAS is a complicated and high-risk pregnancy condition. You will need time and space to make sense of what this means for you for your pregnancy. As you process the implications of having a high-risk pregnancy, here is a helpful list of questions for you to consult. You can be an informed advocate for yourself and your baby, one-hundred percent involved in the shared decision-making process of your obstetrical care going forward.

  1. Do I have any risk factors for PAS? How are you preparing for the possibility of PAS at my delivery?
  2. Do you know what type of placenta accreta I have?
  3. Do I also have placenta previa?
  4. Will I be referred for specialty pregnancy care or delivery in another hospital or birth setting?
  5. What should I do or who should I call if I start having vaginal bleeding?
  6. Will I be put on bed rest? How active can I be during my pregnancy? Can I have penetrative sexual intercourse?
  7. Will I have a scheduled C-section and what will determine the timing of that C-section?
  8. What can you do to try to preserve my fertility (if desired)? For example, is a cesarean delivery with uterine preservation possible?


  1. Jauniaux E, Hussein AM, Fox KA, Collins SL. New evidence-based diagnostic and management strategies for placenta accreta spectrum disorders. Best Pract Res Clin Obstet Gynaecol. 2019 Nov;61:75-88
  2. Afshar Y, Dong J, Zhao P, Li L, Wang S, Zhang RY, Zhang C, Yin O, Han CS, Einerson BD, Gonzalez TL, Zhang H, Zhou A, Yang Z, Chou SJ, Sun N, Cheng J, Zhu H, Wang J, Zhang TX, Lee YT, Wang JJ, Teng PC, Yang P, Qi D, Zhao M, Sim MS, Zhe R, Goldstein JD, Williams J 3rd, Wang X, Zhang Q, Platt LD, Zou C, Pisarska MD, Tseng HR, Zhu Y. Circulating trophoblast cell clusters for early detection of placenta accreta spectrum disorders. Nat Commun. 2021 Aug 3;12(1):4408.
  3. Xiyao Liu, Yu Wang, Yue Wu, Jing Zeng, Xi Yuan, Chao Tong, Hongbo Qi. What we know about placenta accreta spectrum (PAS), European Journal of Obstetrics & Gynecology and Reproductive Biology. 2021 April;259: 81-89.
Amy Harris
Amy Harris is a certified nurse-midwife with a Master's Degree in Maternal and Child Health from Harvard Chan School of Public Health. Her passions are health literacy and women's reproductive health. A recent two-year sabbatical with her family in Spain was the impetus for becoming a freelance women's health writer. An exercise nut, she is happiest outdoors and on adventures abroad.

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