What is Placenta Accreta?
Placenta accreta is a serious obstetric condition characterized by the abnormal adherence of the placenta to the uterine wall. It poses significant risks during pregnancy and delivery due to the potential for life-threatening hemorrhage. The incidence of placenta accreta has increased over the past few decades, largely due to the rising number of cesarean deliveries and other uterine surgeries. Early recognition and careful management are essential to improving maternal and fetal outcomes.
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Table of Contents
Definition and Classification of Placenta Accreta
Placenta accreta occurs when the placenta attaches too deeply into the wall of the uterus, preventing its normal separation after childbirth.
It is classified into three categories based on the depth of placental invasion:
1. Placenta Accreta (most common): The placental villi attach to the myometrium (the muscular layer of the uterus) without penetrating it.
2. Placenta Increta: The placental villi invade into the myometrium, growing deeper into the uterine muscle.
3. Placenta Percreta: The most severe form, where the villi penetrate through the uterine wall, sometimes extending into adjacent organs like the bladder.
What is the Placenta?
The placenta is a temporary organ that develops in the uterus during pregnancy. It is a vital and complex structure that serves as the life-support system for the developing fetus. The name "placenta" comes from the Latin word for "flat cake," which describes its round, flat shape. It acts as the fetus's lungs, kidneys, liver, and endocrine glands, all in one temporary structure. Its proper development and function are essential for the health and survival of the developing baby.
Causes and Risk Factors
The exact cause of placenta accreta is not fully understood, but it is strongly associated with defective decidualization (the process by which the endometrium prepares for pregnancy), especially in areas of previous uterine scarring. This allows the placental tissue to invade abnormally.
Key Risk Factors
One of the main risk factors for placenta accreta is a previous cesarean delivery. Women who have had a prior cesarean delivery have a higher risk of developing placenta accreta because the scar tissue from the previous surgery can interfere with the implantation of the placenta in subsequent pregnancies.
Other risk factors for placenta accreta include placenta previa (a condition in which the placenta covers the cervix), multiple pregnancies (such as twins or triplets), advanced maternal age, a history of uterine surgery, and certain medical conditions such as endometriosis and Asherman's syndrome (a condition in which scar tissue forms inside the uterus).
Placenta accreta can also occur in women who have never been pregnant, although this is rare. In these cases, the condition is usually associated with a molar pregnancy, a type of abnormal pregnancy in which a tumor develops instead of a normal fetus.
Overall, the exact cause of placenta accreta is not entirely clear, but it is believed to be related to problems with the formation and development of the placenta.
Clinical Presentation of Placenta Accreta
The clinical presentation of placenta accreta can be subtle and is often asymptomatic during early pregnancy. Many cases are discovered incidentally during routine prenatal imaging or diagnosed intrapartum when complications arise during delivery. The presentation varies depending on the depth of placental invasion (accreta, increta, or percreta) and whether the condition is diagnosed antenatally (before delivery) or postnatally (after delivery).
1. Asymptomatic in Early Pregnancy
In most cases, placenta accreta does not cause any symptoms during the early stages of pregnancy. Many pregnant individuals will not experience any warning signs, and the condition may only be suspected or diagnosed during a second or third trimester ultrasound, especially in women with risk factors such as placenta previa or previous cesarean sections. In fact, up to 50–60% of cases are diagnosed antenatally through imaging, rather than by clinical symptoms.
2. Antepartum Signs and Symptoms
Some individuals with placenta accreta may present with symptoms later in pregnancy, most commonly:
🔹 Painless vaginal bleeding in the second or third trimester: This is often the result of placenta previa, which is commonly associated with placenta accreta. While bleeding may not be directly due to accreta itself, its presence should raise suspicion, especially in women with previous uterine surgery.
🔹 Abnormal ultrasound findings: The most common clinical clue comes from ultrasound or Doppler studies, which may show placental lacunae (vascular spaces), absence of the normal hypoechoic zone between the placenta and myometrium, or turbulent blood flow indicating abnormal vascularization.
🔹 Fundal height abnormalities: In some cases, especially with placenta percreta involving the bladder, the uterine size may be larger than expected for gestational age.
3. Intrapartum Presentation
For undiagnosed cases, the clinical presentation may become evident during labor and delivery, particularly:
🔹 Difficulty with placental separation: After the birth of the baby, the placenta fails to detach from the uterine wall, or only partially detaches.
🔹 Massive postpartum hemorrhage: This is the most dramatic and dangerous presentation. When attempts are made to manually remove the placenta, it can lead to severe, life-threatening bleeding that does not respond to routine uterotonic medications.
🔹 Need for emergency hysterectomy: In cases of placenta increta or percreta, where the placenta invades deeply, removing the uterus may become the only life-saving option.
4. Postpartum Findings (When Diagnosis Is Missed During Pregnancy)
When placenta accreta is not identified before or during delivery, complications may arise in the postpartum period, such as:
🔹 Delayed postpartum hemorrhage
🔹 Infection or sepsis, especially if placental tissue remains in the uterus
🔹 Retained placenta fragments, visible on postpartum ultrasound
🔹 Uterine rupture or perforation, especially in percreta cases
5. Associated Findings in Severe Cases
In placenta percreta, where the placenta invades through the uterine wall and into adjacent organs like the bladder or bowel, symptoms may include:
🔹 Hematuria (blood in urine) due to bladder involvement
🔹 Pelvic or lower abdominal pain
🔹 Recurrent urinary tract infections
These signs are uncommon but may be present in severe or neglected cases.
The clinical presentation of placenta accreta can range from completely silent to catastrophic. Most cases are detected through routine imaging in high-risk pregnancies, but when undiagnosed, they may present dramatically with postpartum hemorrhage and retained placenta. Therefore, a high index of suspicion and thorough antenatal assessment are crucial, particularly in women with known risk factors such as previous cesarean deliveries or placenta previa.(alert-passed)
Complications of Placenta Accreta
Placenta accreta is a serious obstetric condition associated with significant maternal and fetal morbidity and mortality. The complications depend on the degree of placental invasion (placenta accreta, increta, or percreta), the timing of diagnosis, and the availability of experienced obstetric and surgical teams. Prompt recognition and management are essential to reduce the risk of life-threatening outcomes.
1. Massive Postpartum Hemorrhage (PPH)
The most common and life-threatening complication of placenta accreta is severe bleeding, especially during the attempted removal of the placenta after delivery. Because the placenta is abnormally attached to the uterine wall and cannot separate normally, efforts to remove it can cause profuse hemorrhage. Blood loss can range from hundreds to thousands of milliliters within minutes, leading to:
✔ Hemodynamic instability
✔ Hypovolemic shock
✔ Disseminated intravascular coagulation (DIC)
✔ Increased risk of maternal mortality
This complication often necessitates massive blood transfusions, use of blood products (such as platelets, FFP, cryoprecipitate), and advanced resuscitation efforts.
2. Emergency Hysterectomy
Due to the high risk of uncontrollable bleeding, hysterectomy (surgical removal of the uterus) is often the only definitive management to control hemorrhage, particularly in placenta increta and percreta. This results in:
✔ Loss of fertility, which can have emotional and psychological consequences
✔ Increased surgical risks, including injury to nearby organs
In some cases, a planned cesarean hysterectomy is performed in a controlled setting if placenta accreta is diagnosed antenatally.
3. Injury to Surrounding Organs
In placenta percreta, where the placenta penetrates through the uterine wall and may invade nearby organs such as the bladder, ureters, or bowel, the risk of injury during surgery is significant. This can result in:
✔ Bladder rupture or fistula formation
✔ Ureteral injury
✔ Need for partial cystectomy (removal of part of the bladder)
✔ Postoperative urinary incontinence or infections
These complications often require multidisciplinary surgical care involving urologists and general surgeons.
4. Infections and Sepsis
Following delivery, retained placental tissue or surgical intervention can predispose patients to uterine infections or pelvic sepsis. This risk is especially high if conservative (non-surgical) approaches are attempted without adequate follow-up. Symptoms may include:
✔ Fever
✔ Abdominal pain
✔ Foul-smelling vaginal discharge
✔ Elevated white cell count
Severe infections can progress to septic shock, especially in resource-limited settings.
5. Thromboembolic Events
Patients undergoing major surgery, experiencing hemorrhage, or receiving multiple blood transfusions are at elevated risk for venous thromboembolism (VTE), including:
✔ Deep vein thrombosis (DVT)
✔ Pulmonary embolism (PE)
Postpartum patients with prolonged immobility, major blood loss, or ICU admission require careful thromboprophylaxis.
6. Psychological and Emotional Impact
The abrupt nature of complications, emergency surgery, and loss of fertility can have a profound psychological impact on the mother. Women may experience:
✔ Postpartum depression
✔ Anxiety
✔ Post-traumatic stress disorder (PTSD)
✔ Grief or distress related to hysterectomy and future fertility
Psychological support and counseling should be part of the comprehensive management plan.
7. Fetal Complications
While placenta accreta primarily affects the mother, there are significant fetal risks, especially when early delivery is necessary:
✔ Preterm birth, often iatrogenic due to the need for planned early cesarean delivery
✔ Low birth weight
✔ Neonatal intensive care admission
✔ Respiratory distress syndrome
In severe maternal cases, fetal demise may also occur, particularly if maternal hemodynamic instability is prolonged.
Placenta accreta is associated with a range of serious and potentially life-threatening complications, particularly massive postpartum hemorrhage and surgical morbidity. Early diagnosis, careful planning of delivery, and multidisciplinary management involving obstetricians, anesthesiologists, urologists, and neonatologists are essential to reduce maternal and fetal risks. With proper care in a well-equipped center, many of these complications can be anticipated and managed effectively.(alert-passed)
Diagnosis of Placenta Accreta
The diagnosis of Placenta Accreta Spectrum (PAS)—which includes placenta accreta, increta, and percreta—is critical for planning appropriate obstetric care and minimizing maternal and fetal risks. While some cases are diagnosed antepartum (before delivery), others may only be discovered intrapartum (during delivery) when the placenta fails to detach normally. Early diagnosis, ideally in the second or early third trimester, allows for multidisciplinary planning to reduce complications.
1. Clinical History and Risk Factors
A thorough maternal history is the first step in identifying women at risk for placenta accreta. Important risk factors include:
✔ Previous cesarean delivery, particularly if combined with placenta previa
✔ History of uterine surgery (e.g., myomectomy, D&C)
✔ Multiparity
✔ Advanced maternal age
✔ Assisted reproductive technology (ART)
A combination of anterior placenta previa and prior cesarean section is the most significant predictor of placenta accreta, and should prompt detailed imaging evaluation.
2. Ultrasound Imaging
Transabdominal and transvaginal ultrasound are the primary tools for antenatal diagnosis of PAS disorders. Ultrasound should be performed by an experienced sonographer, particularly in high-risk patients. Key ultrasound findings suggestive of placenta accreta include:
✔ Loss of the hypoechoic (clear) zone between the placenta and myometrium
✔ Thinning of the myometrium overlying the placenta
✔ Placental lacunae (irregular, vascular spaces within the placenta)
✔ Turbulent blood flow on color Doppler (indicative of abnormal vascularity)
✔ Disruption of the bladder line (in suspected percreta)
Sensitivity and specificity of ultrasound for diagnosing placenta accreta improve with operator experience and targeted assessment.
3. Color Doppler Ultrasound
Color Doppler enhances diagnostic accuracy by assessing abnormal blood flow patterns. Abnormalities seen with Doppler include:
✔ Bridging vessels from the placenta to the bladder
✔ Chaotic blood flow within the placental lacunae
✔ Hypervascularity at the uterine–bladder interface
These features are more pronounced in severe forms, like placenta percreta.
4. Magnetic Resonance Imaging (MRI)
MRI can be used as an adjunct to ultrasound, particularly when the ultrasound findings are inconclusive or if posterior placentation is suspected. MRI is especially useful for:
✔ Evaluating the depth of invasion
✔ Assessing the involvement of surrounding organs, such as the bladder (common in percreta)
✔ Planning surgical intervention
MRI findings of PAS include dark intraplacental bands on T2-weighted images, bulging of the uterus, and disruption of the uterine contour.
5. Intraoperative Diagnosis
In some cases, placenta accreta is only discovered intrapartum, when the placenta fails to detach after delivery of the infant. Features that raise suspicion during surgery include:
✔ Adherence of the placenta to the uterine wall
✔ Profuse bleeding during attempted manual removal
✔ Abnormal placental appearance
If placenta accreta is unexpectedly diagnosed during delivery, a rapid multidisciplinary response is necessary to manage hemorrhage and prevent complications.
6. Role of Histopathology
Definitive diagnosis of the type of placenta accreta (accreta, increta, or percreta) is made by histopathological examination of the uterus or placental bed tissue, typically after hysterectomy. Pathologic findings include:
✔ Placental villi invading into or through the myometrium
✔ Absence of decidua basalis, which normally separates the placenta from the uterus
Histology confirms the diagnosis and guides future counseling.
The diagnosis of placenta accreta relies heavily on clinical risk assessment, targeted ultrasound imaging, and, when necessary, MRI. Early antenatal detection is key for reducing complications through planned cesarean delivery, with or without hysterectomy, in a well-equipped tertiary care setting. Intrapartum diagnosis, although possible, carries higher risks and requires prompt surgical and anesthetic management.(alert-passed)
Management of Placenta Accreta
The management of Placenta Accreta Spectrum (PAS)—which includes placenta accreta, increta, and percreta—requires early diagnosis, multidisciplinary coordination, and a carefully planned delivery to reduce maternal and fetal morbidity and mortality. Management strategies are influenced by the severity of invasion, gestational age, maternal condition, and future fertility desires.
A. Antenatal care
Early detection of placenta accreta is key to effective management. Women who are at increased risk of placenta accreta, such as those with a history of cesarean delivery or placenta previa, should receive regular antenatal care and monitoring.
B. Delivery Planning
In cases where placenta accreta is suspected or diagnosed, delivery should be planned in a tertiary care center with access to a level III neonatal intensive care unit and a blood bank capable of providing massive transfusions. A team of specialists, including obstetricians, anesthesiologists, hematologists, and neonatologists, should be involved in the management of the delivery. In most cases, a scheduled cesarean delivery is recommended to minimize the risk of bleeding and other complications.
C. Timing of Delivery
Elective delivery is typically planned between 34 and 36+6 weeks of gestation, depending on maternal and fetal conditions. This balances the risk of prematurity with the potential for spontaneous labor or hemorrhage.
✔ Corticosteroids may be administered prior to delivery to enhance fetal lung maturity.
✔ Early delivery may be warranted in cases of bleeding, labor, or fetal compromise.
D. Cesarean Hysterectomy (Standard Management)
The gold standard for managing placenta accreta (especially increta and percreta) is cesarean hysterectomy without attempted placental removal. Key aspects include:
✔ Delivery of the infant through a classical (vertical) uterine incision, made away from the placenta.
✔ Leaving the placenta in situ, as attempted removal can result in life-threatening hemorrhage.
✔ Proceeding directly to total or subtotal hysterectomy with the placenta undisturbed.
This approach significantly reduces maternal blood loss and mortality compared to conservative attempts at placental separation.
E. Conservative (Uterus-Sparing) Management
In selected cases—especially when fertility preservation is a priority and bleeding is controlled—conservative management may be attempted. This involves:
✔ Leaving the placenta in situ and monitoring closely.
✔ Administering methotrexate to facilitate placental resorption (though evidence is limited).
✔ Performing uterine artery embolization to control bleeding.
✔ Close follow-up with imaging (e.g., ultrasound, MRI) to monitor placental involution.
This method carries risks such as delayed hemorrhage, infection, and need for delayed hysterectomy, and is not recommended in cases of placenta percreta with bladder invasion or hemodynamic instability.
F. Intraoperative and Postoperative Considerations
Due to the risk of massive hemorrhage, several intraoperative preparations are essential:
✔ Availability of large volumes of blood products
✔ Cell salvage equipment for autologous transfusion
✔ Placement of ureteric stents (if bladder or ureteral involvement is suspected)
✔ Intra-arterial balloon occlusion catheters in the internal iliac arteries or aorta by interventional radiology to reduce bleeding
Postoperative care involves ICU monitoring, management of coagulopathy, and treatment of complications such as infection, wound breakdown, or urinary tract injuries.
G. Management of Unexpected Placenta Accreta
If placenta accreta is diagnosed intraoperatively during an unscheduled cesarean or vaginal delivery:
✔ Attempted manual removal of the placenta should be avoided.
✔ Call for senior surgical and anesthesia staff immediately.
✔ Proceed to emergency hysterectomy if bleeding is uncontrolled.
✔ Stabilize the patient with aggressive resuscitation, including fluids, blood products, and vasopressors if needed.
H. Postpartum Care
Postpartum management of placenta accreta can be complex and requires close monitoring to ensure that the mother receives the appropriate treatment to prevent further complications.
1. Supportive Care: One of the main concerns is the risk of excessive bleeding, which may require blood transfusions to replace lost blood volume. Additionally, medications may be given to control bleeding, such as uterotonics or hemostatic agents.
2. Surgical management: If the placenta was not removed during delivery, a surgical procedure called curettage may be necessary to remove any remaining placental tissue. In severe cases of placenta accreta, a hysterectomy may be necessary to remove the uterus and stop bleeding.
3. Monitoring: Close monitoring for complications is also important, as the risk of infection and blood clots is increased in women with placenta accreta. Antibiotics may be given to prevent or treat infection, and measures such as early mobilization and compression stockings may be used to prevent blood clots.
I. Neonatal care
Babies born to mothers with placenta accreta may require specialized neonatal care, such as monitoring for prematurity or low birth weight, or treatment for other medical issues.
J. Follow-up care
Women who have had placenta accreta should receive follow-up care to monitor for any long-term effects or complications, such as chronic pelvic pain, bladder or bowel problems, or infertility.
The management of placenta accreta must be proactive, not reactive. The cornerstone of safe care is early identification, team-based planning, and delivery at a facility with surgical expertise and critical care resources. Cesarean hysterectomy remains the most effective and safest management for most cases. However, in highly selected patients, conservative management may be considered, though it carries additional risks and requires stringent follow-up.(alert-passed)
Prognosis of Placenta Accreta
Placenta accreta spectrum (PAS) is a serious obstetric condition with a prognosis that depends on timely diagnosis, appropriate planning, and the availability of multidisciplinary care. The spectrum includes placenta accreta (superficial adherence), increta (invasion into the myometrium), and percreta (penetration through the uterine wall into adjacent organs, often the bladder). Each increasing level of invasion carries greater risks and more complex management considerations.
A. Maternal Prognosis
The maternal prognosis for placenta accreta has significantly improved over recent years due to advances in antenatal diagnosis, surgical planning, and critical care management. However, it remains associated with significant maternal morbidity and potential mortality.
1. Hemorrhage and Surgical Complications
The most serious immediate maternal complication is massive obstetric hemorrhage, which may require transfusion of multiple units of blood and blood products. In severe cases, disseminated intravascular coagulation (DIC) or shock can develop. Surgical interventions, particularly cesarean hysterectomy, carry risks of injury to surrounding organs such as the bladder, ureters, or bowel—especially in cases of placenta percreta.
2. Intensive Care and Recovery
Many women require intensive care unit (ICU) admission postoperatively due to the risk of bleeding, infection, or other complications. Recovery may be prolonged, both physically and emotionally, particularly if there is a loss of fertility following hysterectomy.
3. Mortality
Maternal mortality in placenta accreta is significantly reduced when managed in tertiary centers with a multidisciplinary team and planned delivery. In developed settings, maternal death rates are less than 1%, but they are much higher in low-resource settings where access to surgical expertise, blood transfusions, and ICU care is limited.
B. Fetal Prognosis
The fetal prognosis in placenta accreta depends largely on the timing of delivery and the presence of complications such as preterm birth.
1. Preterm Birth
Because delivery is often planned early (typically between 34–36+6 weeks), the most common neonatal complication is prematurity, which may result in respiratory distress, jaundice, or feeding difficulties. Corticosteroids are usually administered antenatally to promote fetal lung maturity and reduce these risks.
2. Survival Rates
With planned delivery and neonatal intensive care support, fetal survival rates are generally high, often exceeding 95% in well-equipped hospitals. However, emergency deliveries due to hemorrhage or placental abruption can increase risks of fetal hypoxia, low birth weight, and neonatal morbidity.
C. Long-Term Outcomes and Recurrence Risk
1. Future Fertility
In cases where a hysterectomy is performed, fertility is lost, which can have a profound psychological impact, especially for women who desire more children. In conservative management cases, fertility may be preserved, though there remains a high risk of recurrence of placenta accreta in future pregnancies.
2. Recurrence
Women who have had placenta accreta are at significantly increased risk of recurrence in subsequent pregnancies—estimates suggest around 20–30% or more, particularly if the uterus has been surgically preserved and the placenta implants over a previous scar.
D. Psychosocial Impact
The emotional toll of placenta accreta can be substantial. Women may experience post-traumatic stress, anxiety, or depression after an emergency delivery, severe hemorrhage, or hysterectomy. Support from psychological services and peer support groups can be essential in recovery.
The prognosis of placenta accreta depends heavily on early recognition, meticulous planning, and delivery in a well-equipped center. While maternal and fetal outcomes have improved significantly with modern care, the condition still carries high risks for hemorrhage, surgical complications, and long-term reproductive consequences.(alert-passed)
