Placenta Accreta: Symptoms, Types, Causes and Treatment

Placenta accreta is a serious pregnancy complication that has become increasingly common in recent decades. This rise is closely linked to the growing number of cesarean deliveries and other uterine surgeries worldwide. Placenta accreta is not just a medical curiosity—it can have profound impacts on maternal health, future fertility, and even survival. In this comprehensive article, we’ll guide you through the symptoms, types, causes, and available treatments for placenta accreta, synthesizing the latest evidence and expert consensus.

Symptoms of Placenta Accreta

Understanding the symptoms of placenta accreta is crucial for timely diagnosis and management. Unfortunately, this condition is often silent during pregnancy, only revealing itself through unexpected complications during delivery or—less commonly—in the weeks following childbirth.

Symptom	Frequency	Clinical Impact	Reference
Vaginal bleeding	Common	Can range from mild to life-threatening	2 4
No symptoms	Frequent	Detected incidentally or at delivery	3 4
Abnormal placenta separation	During delivery	Major cause of hemorrhage and shock	4 5
Delayed postpartum bleeding	Occasional	May occur days to years after delivery	2

Table 1: Key Symptoms

Common and Noteworthy Symptoms

Most women with placenta accreta do not experience any specific symptoms during pregnancy. The placenta typically functions normally, and routine prenatal care may not uncover any issues unless imaging is performed for other reasons 3 4. However, when symptoms do occur, they often present as:

• Vaginal Bleeding: This is the most common clinical sign, particularly in cases where placenta accreta complicates placenta previa (when the placenta lies low in the uterus, covering the cervix) or after pregnancy terminations or uterine procedures. Bleeding can be intermittent, persistent, or, in severe cases, massive and life-threatening 2 4.
• Abnormal Placental Separation: During delivery, especially when attempts are made to remove the placenta, the lack of normal separation can lead to sudden and significant hemorrhage. This is often the first sign that prompts a diagnosis 4 5.
• Delayed or Persistent Bleeding Postpartum: In rare instances, women may develop symptoms days, weeks, or even years after abortion or delivery, especially if placental tissue is retained 2.

Asymptomatic Course

Many cases of placenta accreta are discovered incidentally during ultrasound or at the time of cesarean delivery, when the placenta fails to detach as expected 3 4. This asymptomatic nature underscores the importance of identifying women at risk (see the 'Causes' section below).

Summary

• Bleeding is the hallmark symptom, but many women are asymptomatic until delivery.
• Persistent or delayed bleeding after abortion or childbirth should raise suspicion, particularly in women with risk factors.
• Early and accurate diagnosis can be life-saving.

Types of Placenta Accreta

Placenta accreta is not a single disease but a spectrum. Understanding its different forms helps guide both diagnosis and management.

Type	Definition	Severity	Reference
Accreta	Villi attach to myometrium (no invasion)	Least severe	1 3 4 5
Increta	Villi invade into myometrium	Moderate	1 3 4 5
Percreta	Villi penetrate through uterine wall/serosa	Most severe	1 3 4 5 8

Table 2: Types of Placenta Accreta Spectrum

Placenta Accreta Spectrum: The Three Main Types

Placenta accreta spectrum disorders are classified based on the depth of placental invasion into the uterine wall 1 3 4 5:

• Placenta Accreta (creta): The placenta attaches too deeply to the uterine wall but does not invade the muscle (myometrium) itself. This form is the most common and least severe.
• Placenta Increta: Here, the placental villi invade into the myometrium. This is a more serious condition, often associated with increased risk of hemorrhage.
• Placenta Percreta: The most severe type, where the placenta penetrates through the entire uterine wall, sometimes invading adjacent organs like the bladder. However, emerging evidence suggests true transmural invasion is less common than previously thought, and many cases are due to severe scarring and uterine pathology rather than actual placental tissue crossing into other organs 8 9.

Clinical Implications

• Severity increases across the spectrum, with percreta carrying the highest risk of catastrophic bleeding and organ damage.
• Diagnosis often relies on imaging (ultrasound, MRI) and surgical findings. However, distinguishing between these subtypes before delivery is challenging, and overlapping features may exist 1 3.
• Management strategies and prognosis vary with the type and extent of invasion.

Summary

• Placenta accreta spectrum includes accreta, increta, and percreta.
• The deeper the invasion, the greater the risk and complexity of management.
• Precise diagnosis can be difficult prior to delivery.

Causes of Placenta Accreta

Placenta accreta is mainly an acquired condition, closely tied to previous uterine surgery or trauma. Understanding what causes it is key to prevention and risk assessment.

Cause/Risk Factor	Mechanism	Risk Level	Reference
Prior cesarean section	Scar impairs normal placental attachment	High	1 3 4 5 7 9
Placenta previa	Low-lying placenta implants over scar	High	3 4 5 7
Uterine surgery	Curettage, myomectomy, etc. damages endometrial interface	Moderate	1 2 7
Advanced maternal age	Age-related changes to uterine tissue	Moderate	2 6

Table 3: Main Causes and Risk Factors

Surgical Scarring and the Endometrial-Myometrial Interface

• Previous Cesarean Delivery: This is by far the single most important risk factor. Each additional cesarean increases the risk of developing placenta accreta in subsequent pregnancies 1 3 4 5 7 9.
• Placenta Previa After Cesarean: When the placenta implants over a previous uterine scar (especially in the lower segment), the chance of accreta rises dramatically 3 4 5 7.
• Other Uterine Surgeries: Procedures like dilation and curettage, myomectomy, or manual removal of the placenta can disrupt the critical barrier between the lining of the uterus (endometrium) and its muscle (myometrium). This disruption prevents normal separation at delivery and promotes abnormal placental attachment 1 2 7.

Pathophysiology: Not Just “Too Much Invasion”

• Recent research suggests that placenta accreta is not due to an inherently “invasive” placenta, but rather to a failure of normal uterine healing and remodeling after surgery. The placenta simply takes advantage of areas where the uterine wall is thin or scarred, allowing it to attach more deeply 1 7 9.
• Abnormal Vascularization: Scarred areas may also have altered blood supply, which can affect how the placenta grows and attaches 7 9.

Additional Risk Factors

• Advanced Maternal Age: Women aged 35 and older are at increased risk, possibly due to cumulative effects of age and surgical interventions 2 6.
• History of Uterine Infection or Endometritis: Previous infections can also damage the uterine lining, increasing subsequent risk 1.
• Multiple Pregnancies and Assisted Reproduction: Some studies suggest these factors may play a role, but the evidence is less robust.

Summary

• The overwhelming majority of placenta accreta cases are iatrogenic—caused by prior medical procedures.
• Cesarean scars and uterine surgeries are the main culprits; the more procedures, the higher the risk.
• Prevention efforts center on limiting unnecessary uterine surgery and careful placement of the placenta in women with prior scars.

Treatment of Placenta Accreta

Treating placenta accreta requires a tailored approach, balancing the mother’s health, future fertility wishes, and available medical resources. Management has evolved significantly, with both surgical and conservative options now available.

Treatment Option	Aim/Approach	Uterus Preservation	Reference
Cesarean hysterectomy	Remove uterus with placenta in situ	No	4 5 11
Conservative management	Leave placenta in situ, adjunct therapies	Yes (attempted)	10 12 13
One-step resective-reconstructive surgery	Remove placental area, repair uterus	Yes (select cases)	6
Adjunct therapies	Embolization, methotrexate, vessel ligation	Yes (supportive)	2 10 13

Table 4: Treatment Options for Placenta Accreta

Standard Approach: Cesarean Hysterectomy

• Traditional Gold Standard: The most common and definitive treatment remains cesarean hysterectomy—removing the uterus with the placenta left in place. This method minimizes the risk of catastrophic hemorrhage, which can occur if the placenta is forcibly removed 4 5 11.
• When is it Used: This is preferred when the diagnosis is made prenatally, the invasion is extensive, or resources for conservative management are lacking. It is also the default in low-resource settings 11.

Conservative (Uterus-Sparing) Management

• Leaving Placenta In Situ: In select cases, especially when future fertility is desired or when hysterectomy would be especially risky, the placenta may be left in place. Over time, the body may resorb the placental tissue 10 12 13.

• Adjunct Therapies:

  • Uterine artery embolization: Blocks blood flow to the placenta, helping control bleeding 2 10 13.
  • Methotrexate: A chemotherapy drug used to accelerate placental tissue breakdown, though its benefit is debated 13.
  • Surgical vessel ligation: Tying off blood vessels to reduce blood loss during or after delivery 13.

• Success and Risks: Conservative management is successful in about 75–80% of cases, but requires close monitoring for infection, delayed hemorrhage, and possible need for later hysterectomy 10 13. Some women may develop complications such as sepsis or uterine necrosis, though these are relatively rare in centers with proper resources.

One-Step Resective-Reconstructive Surgery

• Advanced Surgical Technique: This approach involves removing the affected portion of the uterus and placenta together (“en bloc”) and reconstructing the uterus. It has shown promise in preserving the uterus in up to 80% of carefully selected cases, especially with less extensive invasion 6.
• Best Candidates: Those with limited or localized involvement and access to experienced surgical teams 6.

Future Fertility and Recurrence

• Potential for Future Pregnancy: After successful conservative management, many women retain their fertility and can have healthy pregnancies. However, the risk of recurrent placenta accreta in subsequent pregnancies is high (up to 29%), and close monitoring will be essential 12.
• Counseling and Individualized Care: All women should be counseled regarding the risks, benefits, and possible need for further intervention in the future.

Delivery Planning and Multidisciplinary Care

• Antenatal Diagnosis is Key: Identifying placenta accreta before delivery allows for planned delivery at a specialized center with multidisciplinary teams, access to blood transfusions, and intensive care support 5.
• Team Approach: Optimal outcomes are achieved in centers with expertise in complex obstetric surgery, interventional radiology, anesthesia, and transfusion medicine 5 11.

Summary

• Cesarean hysterectomy is the standard, especially with extensive invasion or limited resources.
• Conservative approaches can preserve fertility but carry risks and require specialized care.
• New surgical techniques may further reduce the need for hysterectomy in select cases.

Conclusion

Placenta accreta is a growing challenge in modern obstetrics, but advances in diagnosis and treatment are improving outcomes for mothers and babies. Key takeaways include:

• Symptoms: Most women are asymptomatic; vaginal bleeding—during or after delivery—is the primary warning sign.
• Types: Placenta accreta spectrum includes accreta, increta, and percreta, reflecting the depth of placental invasion.
• Causes: Prior cesarean delivery and other uterine surgeries are the main risk factors; prevention focuses on limiting unnecessary uterine interventions.
• Treatment: Cesarean hysterectomy remains the standard, but conservative and uterus-sparing options are increasingly viable in specialized centers.

Timely diagnosis, personalized treatment planning, and care at high-level maternal centers are essential to optimizing outcomes for women facing this serious complication.

This article provides evidence-based information to empower women and healthcare providers to recognize, prevent, and manage placenta accreta spectrum disorders.