What Is Placenta Percreta? Causes, Detection, and Surgery

Placenta percreta is the most severe form of placenta accreta spectrum disorders, a condition in which the placenta grows completely through the uterine wall and can invade neighboring organs such as the bladder or, less commonly, the bowel. It sits at the extreme end of a spectrum that also includes the milder accreta (placenta attached too firmly) and increta (placenta grows into the uterine muscle) grades. Percreta accounts for a minority of all accreta spectrum cases, but it carries the highest risk of life-threatening hemorrhage, organ damage, and surgical complexity. Understanding what drives this condition, how it is detected before delivery, and what its management looks like is relevant for anyone facing the diagnosis or supporting someone who is.

What Causes Placenta Percreta

The prevailing explanation centers on the uterine lining rather than the placenta itself. Under normal circumstances, a layer of tissue called the decidua acts as a barrier that limits how deeply the placenta’s anchoring cells can burrow into the uterine wall. When that barrier is damaged or absent, nothing stops those cells from migrating all the way through the muscle and beyond. Research continues to support the idea that the problem is a defective decidua rather than a placenta that is inherently too aggressive.¹ A 2025 review in the American Journal of Obstetrics and Gynecology put it plainly: the condition arises at sites where the normal mechanisms that limit cell migration are simply missing, not because the placental tissue is abnormally invasive on its own.²

The most common source of that decidual damage is a prior cesarean section scar. When a blastocyst implants over or near the scar, it attaches to tissue that never fully healed, where the protective decidual and muscle layers are thin or absent. Large scar defects in the lower part of the uterus are especially problematic because they allow placental cells to reach close to the outer surface of the uterus.³ At the molecular level, enzymes called matrix metalloproteinases, particularly MMP-9, appear to be overexpressed in accreta tissue. These enzymes break down the structural scaffolding around cells, which may explain why trophoblast cells migrate so far in areas where the decidual brake is already gone.⁴ Researchers have also found altered patterns of blood-vessel growth signals in accreta tissue, including changes in proteins that regulate new vessel formation, which helps explain the dense, fragile blood supply that makes surgical management so challenging.⁵

Who Is at Risk

The single biggest risk factor is a history of cesarean delivery combined with a placenta that sits low in the uterus (placenta previa). In a large prospective population-based study, the rate of accreta spectrum disorders ranged from about 5 percent in women with one prior cesarean and a posterior low-lying placenta all the way up to 63 percent in women with three or more prior cesareans and full placenta previa.⁶ Each additional cesarean scar compounds the risk, because the cumulative damage to the uterine lining grows with each surgery.

In vitro fertilization has also emerged as an independent risk factor. One study found that after adjusting for prior cesarean deliveries, IVF pregnancy still carried roughly a sevenfold increase in the odds of accreta spectrum disorders.⁷ A separate retrospective study found that IVF pregnancies had double the rate of accreta spectrum compared with non-IVF pregnancies, and that frozen embryo transfers were associated with an even higher risk than fresh transfers.⁸ The reasons are not entirely understood, but the hormonal preparation of the uterine lining during IVF cycles and the mechanics of embryo transfer may alter how the decidua develops at the implantation site.

Other contributing factors include prior uterine surgeries such as fibroid removal or dilation and curettage, uterine abnormalities, and advanced maternal age. But the combination of a scarred uterus and a low-lying placenta overwhelms the others in terms of statistical weight. In that same study of independent risk factors, placenta previa alone had an adjusted odds ratio of nearly 95.⁹

How Percreta Is Detected Before Delivery

Prenatal diagnosis matters enormously. When percreta is identified in advance, the delivery can be planned at a hospital with the right surgical teams, blood bank capacity, and intensive-care support. When it is not, the condition is discovered on the operating table, and outcomes are worse.

Ultrasound is the first-line tool. A systematic review and meta-analysis of its accuracy found that ultrasound detected percreta with about 81 percent sensitivity and 99 percent specificity. For the milder forms of the spectrum, sensitivity was somewhat higher, around 90 to 93 percent.¹⁰ Specific ultrasound signs help predict how deep the invasion goes. The loss of a normally visible “clear zone” between the placenta and the uterine wall is a well-known marker, but its sensitivity varies by grade. Hypervascularity at the junction of the uterus and bladder is particularly useful for identifying the deeper forms: sensitivity for percreta was about 86 percent with that sign.

MRI serves as a second-line tool when ultrasound findings are inconclusive or when the placenta is posterior and hard to visualize with ultrasound alone.¹¹ MRI’s main advantage is in mapping exactly how far the invasion extends beyond the uterus. A prospective study of high-risk patients found that MRI was 100 percent sensitive for identifying invasive placenta and was highly specific for detecting extension into the bladder and the tissue alongside the uterus.¹² This kind of surgical road map is especially valuable in percreta, where the operating team needs to know before they begin whether the bladder, ureters, or parametrial tissue are involved.

The Surgical Reality

For most percreta cases, the planned treatment is cesarean hysterectomy: the baby is delivered through an incision in the upper part of the uterus, and then the uterus is removed with the placenta still inside, deliberately avoiding any attempt to separate the placenta from the uterine wall. Trying to pull the placenta off triggers catastrophic bleeding. The surgical steps are numerous and deliberate. Ureteral stents are placed before surgery so the surgeon can feel where the ureters run and avoid cutting them. The uterine incision is made at a point well away from the placenta. When bladder invasion is present, partial bladder removal and repair may be necessary.¹³

Bladder involvement is far from rare in percreta. In one series of planned hysterectomies for percreta, about a third of patients had placental invasion into the bladder or ureter requiring urological repair.¹⁴ Another center reported a bladder injury rate of about 25 percent in their cesarean hysterectomy series for increta and percreta cases combined, along with two ureteric injuries.¹⁵ This is why a urologist is considered a core member of the surgical team, not a backup.

Controlling Blood Loss

Hemorrhage is the defining danger. Average blood loss during cesarean hysterectomy for percreta can easily exceed two liters, and extreme cases can reach five or more. One strategy that has gained widespread acceptance is preoperative placement of balloon occlusion catheters in the internal iliac (hypogastric) arteries. When inflated during surgery, these balloons temporarily reduce blood flow to the pelvis. A study comparing patients who received balloon catheterization with those who did not found that blood loss was about 40 percent lower and the volume of blood transfused was about 50 percent lower in the balloon group.¹⁶ Earlier case reports also documented a marked drop in operative blood loss when balloon occlusion and embolization of the internal iliac arteries were used during percreta surgeries.¹⁷

Even with these precautions, massive transfusion protocols are often activated. In a case report from a resource-limited setting, a patient with accreta spectrum received 14 units of packed red blood cells, 10 units of plasma, and 12 units of platelets during a single operation, alongside anti-bleeding medication and continuous blood-pressure support.¹⁸ Having blood products immediately available and a transfusion plan in place before the first incision is non-negotiable in percreta cases.

Why Multidisciplinary Teams Change Outcomes

Percreta management is not a one-surgeon operation. It routinely involves obstetricians, gynecologic oncologists or pelvic surgeons, urologists, interventional radiologists, anesthesiologists with experience in massive hemorrhage, neonatologists, and blood-bank specialists. A study that tracked outcomes over time at a single center performing two to three accreta spectrum cases per month found that outcomes steadily improved as the team gained collective experience, suggesting that small, continuous refinements in teamwork drive better results.¹⁹

Some centers have also explored delayed hysterectomy as an alternative to removing the uterus at the same time as the cesarean delivery. In this approach, the baby is delivered, the placenta is left in place, and the hysterectomy is performed days to weeks later, after the blood supply to the placenta has diminished. One institutional comparison found that both estimated blood loss and transfusion requirements were significantly lower in the delayed-hysterectomy group compared with the conventional single-stage hysterectomy group. Massive transfusion was not needed in any of the delayed cases.²⁰

Can the Uterus Be Saved

For women who strongly wish to preserve fertility, some centers have attempted conservative management: the baby is delivered, the placenta is left inside the uterus, and the body is given months to reabsorb it, sometimes with the help of arterial embolization to cut off its blood supply. One case series of 21 patients managed this way found that the average time for the residual placenta to be naturally reabsorbed was about five months. But the complication rate was substantial: roughly one in five patients had delayed postpartum hemorrhage, more than half developed infections, three progressed to sepsis, and four ultimately needed a hysterectomy anyway.²¹ No maternal deaths were reported, but the data make clear that conservative management of percreta is not a low-risk choice. It trades the certainty of hysterectomy for months of monitoring, repeated imaging, and a meaningful chance of serious infection.

When to Deliver

Delivery timing in accreta spectrum is a balancing act between giving the baby more time to mature and avoiding an emergency situation. Antepartum bleeding, which is common when placenta previa accompanies percreta, can force the team’s hand. A recent study used a standardized algorithm based on cervical length and bleeding episodes to guide delivery timing between 34 and 36 weeks of gestation. Women with a long cervix and no bleeding delivered around 35 to 36 weeks, while those with a short cervix and multiple bleeding episodes delivered as early as 33 weeks.²²

Emerging evidence suggests that at specialized centers, waiting a bit longer may be safe. A 2025 study concluded that patients without active complications like bleeding, labor, or preeclampsia can have planned delivery in the late preterm or early term period without worsening maternal outcomes, while meaningfully improving neonatal outcomes.²³ The trade-off here is geographic: “later is feasible” depends on having the full surgical team available on short notice if things change.

What Percreta Means for the Baby

Because most accreta spectrum deliveries happen before full term, babies face the usual risks of prematurity: breathing difficulties, feeding problems, and time in the neonatal intensive care unit. But there appears to be an added layer of risk. A study comparing neonates born from accreta spectrum pregnancies with gestational-age-matched controls found that breathing trouble was nearly twice as common in the accreta group, affecting about 37 percent versus 21 percent of controls. The excess risk was particularly pronounced at later gestational ages, suggesting that prematurity alone does not explain the difference.²⁴

A more recent 11-year retrospective study identified several predictors of respiratory compromise in these babies, including the grade of accreta spectrum, whether the mother had vaginal bleeding in the 24 hours before delivery, whether antenatal corticosteroids were given, birth weight, gestational age, and the baby’s sex. Percreta specifically carried the highest weighting among the placenta-type categories in their predictive model.²⁵ The practical implication is that neonatologists should be present at every delivery and prepared for respiratory support even when the baby is delivered at a reasonable gestational age.

The Financial Weight

Percreta is among the most expensive conditions in obstetrics. A cost analysis comparing early versus later delivery timing found that total care costs were significantly higher in the early delivery group, with a median exceeding $360,000 compared with roughly $246,000 for later delivery. The maternal cost difference was driven largely by longer hospital stays for antepartum bleeding, while the neonatal cost difference came from extended NICU time, where median costs for the early group were about five times higher than for the later group.²⁶ These numbers underscore why delivery timing decisions matter beyond the clinical: every extra week of stability can translate to substantially lower costs for both mother and child.

The Psychological Aftermath

The physical recovery from percreta surgery tends to dominate clinical conversations, but the psychological toll deserves more attention. A cross-sectional study that assessed women after accreta spectrum disorders using a validated trauma scale found a mean score that hovered near the threshold for post-traumatic stress disorder, with roughly a third of participants scoring in the intermediate or high-risk range. The strongest psychological burden came from intrusive symptoms: unwanted thoughts, images, and memories of the experience.²⁷

Qualitative research has painted a richer picture. Interviews with parents after accreta spectrum experiences identified themes including living with a changed body, the strain on relationships, challenges navigating routine postnatal care that was not designed for their situation, and, on the more hopeful side, a sense of post-traumatic growth.²⁸ Many women described feeling that their emotional recovery was invisible to the healthcare system, which focused almost entirely on wound healing and blood counts. These findings argue for building psychological screening and follow-up into the standard care pathway, rather than treating it as an afterthought.

Why Diagnosis and Classification Remain a Moving Target

One of the frustrating realities of accreta spectrum research is that different centers have historically defined the condition differently. Some rely on what the surgeon sees at the time of delivery, some on pathologic examination of the removed uterus, and some on imaging alone. This inconsistency makes it difficult to compare studies and determine true prevalence. The International Federation of Gynecology and Obstetrics (FIGO) published a consensus classification system specifically to address this problem, emphasizing the need to distinguish between the adherent forms (where the placenta is stuck but has not deeply invaded) and the truly invasive forms like percreta.²⁹ Until more centers consistently apply this classification and confirm it with pathology, published rates of percreta will remain somewhat unreliable, and comparing surgical outcomes across institutions will continue to be an apples-to-oranges exercise.