Not medical advice. ClearTerm Health is an informational resource created by a patient advocate, not a medical professional. Always consult your doctor or MFM specialist for guidance specific to your situation.
Common questions
Frequently asked questions
Plain language answers to the questions women ask most after a placenta previa or accreta diagnosis.
About your diagnosis
Yes — in many cases, particularly when diagnosed early in the second trimester. As the uterus grows, the placenta can appear to "migrate" upward and away from the cervix. Studies suggest that the majority of low-lying placentas identified at the 20-week anatomy scan will resolve by 36 weeks. However, a complete previa detected late in pregnancy is far less likely to resolve and usually requires cesarean delivery. Follow-up ultrasounds at 32–36 weeks are standard to assess whether resolution has occurred.
These three terms describe increasing depths of abnormal placental attachment. In placenta accreta, the placenta attaches too firmly to the uterine wall but does not penetrate the muscle layer. In placenta increta, the placenta grows into the uterine muscle. In placenta percreta — the most severe form — the placenta penetrates entirely through the uterine wall and may attach to adjacent organs such as the bladder or bowel. Together, these are called the Placenta Accreta Spectrum (PAS).
Placental lakes — also called lacunae — are irregular pools of blood visible on ultrasound within the placenta. They appear as dark, irregular spaces and are one of the earliest and most significant ultrasound signs of placenta accreta spectrum. In a normal placenta, the tissue appears uniform and solid. When lacunae are present, particularly multiple large ones, it suggests the placenta has grown abnormally into or through the uterine wall. The more lacunae present, and the larger they are, the higher the suspicion for PAS. A "Swiss cheese" appearance on ultrasound — multiple dark holes scattered through the placenta — is a term commonly used to describe this finding. If your ultrasound report mentions lacunae, placental lakes, or a loss of the clear zone between the placenta and uterus, ask your provider directly about PAS screening and whether a referral to a Maternal-Fetal Medicine specialist or MRI is warranted. This finding alone does not confirm PAS, but it should always be taken seriously and investigated further.
Yes. Uterine scarring from prior cesarean delivery significantly increases the risk of both placenta previa and placenta accreta spectrum in future pregnancies. The risk is cumulative — with one prior C-section, the PAS risk is approximately 0.3%; with two it rises to around 0.6%; with three or more the risk can exceed 2%. Other uterine surgeries — including myomectomy, D&C, and endometrial ablation — also create scar tissue that raises PAS risk, even without a prior C-section.
Yes — research increasingly shows that IVF pregnancies, particularly those using frozen embryo transfer (FET) in a hormone replacement cycle, carry a significantly elevated risk of placenta accreta spectrum. One large study found that women who underwent IVF had more than 5 times the risk of PAS compared to non-IVF pregnancies. If you conceived via IVF, particularly through frozen embryo transfer, speak with your OB or MFM about targeted PAS screening even if you have no prior uterine scars.
Delivery & care
For complete or major placenta previa, vaginal delivery is not safe and cesarean section is required. For a low-lying placenta where the edge is within 2 cm of the cervical os, vaginal delivery may sometimes be possible under close monitoring, but this depends on individual circumstances and should be thoroughly discussed with your MFM specialist. A marginal previa at the edge of the os is typically still managed with cesarean delivery at most institutions.
A PAS Center of Excellence is a hospital that has a dedicated multidisciplinary team experienced in managing placenta accreta spectrum deliveries. These centers have protocols in place for high blood loss, including cell salvage, massive transfusion protocols, interventional radiology support, and surgical specialists. The Accreta Foundation and SMFM both advocate for women with PAS to deliver at such centers, as outcomes are significantly better compared to institutions without this specialized experience.
If you had a cesarean hysterectomy as part of your PAS delivery, carrying another pregnancy is no longer possible since the uterus has been removed. However, if your ovaries were preserved, you may still have biological children through gestational surrogacy — a surrogate carries an embryo created from your eggs and your partner's sperm.
If you had a conservative management approach where your uterus was preserved, future pregnancy may be possible but carries a significantly elevated risk of PAS recurring. Many women in this situation choose to complete their families before attempting another pregnancy, and close monitoring with an MFM specialist is essential.
If this question matters to you, it's worth discussing fertility preservation options with your care team before delivery.
For placenta previa without accreta, delivery is typically planned at 36–37 weeks. For placenta accreta spectrum, most centers recommend delivery at 34–36 weeks — before labor begins, which significantly reduces the risk of emergency bleeding. For percreta or very complex cases, some centers may recommend even earlier delivery depending on imaging findings and clinical stability. Your MFM will recommend the timing that's right for your specific situation.
Plan for a longer stay than a typical delivery — most PAS patients spend 3–7 days inpatient, sometimes longer. Bring comfortable loose clothing that's easy to get on and off around an IV and abdominal dressing, slip-on shoes, a phone charger, headphones, and items that bring you comfort. If you're breastfeeding, bring your pump. Have someone prepare your home for limited mobility before you leave — you won't be able to lift, drive, or climb stairs for several weeks. Most importantly, arrange for someone to be with you the first 1–2 weeks home.
Key questions to consider: What type of previa or PAS do I have, and how confident are you in the diagnosis? Should I be referred to a Maternal-Fetal Medicine specialist? Will I need additional imaging (MRI)? What activity restrictions do I need to follow? Where should I deliver, and does that facility have a multidisciplinary PAS team? What are the warning signs I should watch for at home? When would you recommend early delivery, and will my baby need NICU support? If hysterectomy is a possibility, what are my options for discussing fertility preservation?
Medical Disclaimer: The content on this page is for informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of your obstetrician, MFM specialist, or other qualified health provider. In an emergency, call 911 immediately.