Introduction
Placenta accreta spectrum (PAS), previously termed morbidly adherent placenta, encompasses a range of conditions characterized by the abnormal invasion of placental trophoblasts into the uterine myometrium. This spectrum includes placenta accreta, increta, and percreta, each denoting increasing depth of myometrial invasion. The primary concern with PAS is the potential for severe maternal hemorrhage, often necessitating blood transfusions and contributing to increased maternal morbidity and mortality. Elevated rates of maternal mortality are associated with PAS, alongside a higher likelihood of peripartum or postpartum hysterectomy and prolonged hospital stays. In light of these risks, the American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal–Fetal Medicine have designated PAS as a high-risk condition requiring management at Level III (subspecialty) or Level IV maternal care facilities. These centers offer continuous access to specialized medical staff experienced in managing complex obstetric complications like PAS, along with essential resources such as critical care specialists, hematologists, and blood banks equipped for massive transfusions. Effective Diagnosis For Ob Care settings is paramount to ensure timely intervention and optimal patient outcomes in PAS.
Rising Incidence of Placenta Accreta Spectrum
The incidence of placenta accreta spectrum is demonstrably on the rise. Historical data from the 1970s and 1980s reported prevalence rates between 1 in 2,510 and 1 in 4,017 births. However, by 1982–2002, this rate had increased to approximately 1 in 533. More recent data from a 2016 study utilizing the National Inpatient Sample indicated a significantly higher rate of 1 in 272 birth-related hospital discharges in the United States. This escalating trend over recent decades is largely attributed to changes in maternal risk factors, most notably the increased frequency of cesarean deliveries.
Key Risk Factors in Obstetric Patients
Several risk factors contribute to the development of placenta accreta spectrum, with prior cesarean delivery being the most prominent. The risk of PAS escalates with each subsequent cesarean. A systematic review quantified this increased risk, noting a rise from 0.3% in women with one prior cesarean to 6.74% in those with five or more. Additional factors include advanced maternal age, multiparity, previous uterine surgeries or curettage, and Asherman syndrome.
Placenta previa is another significant risk factor strongly correlated with PAS. In women with placenta previa and no prior cesarean deliveries, the incidence of PAS is about 3%. However, this risk dramatically increases in the presence of placenta previa and a history of cesarean deliveries. For women with placenta previa, the risk of PAS is approximately 3%, 11%, 40%, 61%, and 67% with the first, second, third, fourth, and fifth or more cesarean deliveries, respectively.
Furthermore, abnormal placental biomarker levels have been linked to an elevated risk of PAS. For instance, unexplained elevations in maternal serum alpha-fetoprotein have been associated with increased PAS risk. However, it’s important to note that maternal serum alpha-fetoprotein is not a reliable predictor for clinical use due to its poor predictive accuracy. Other placental analytes implicated in PAS include pregnancy-associated plasma protein A, pro B-type natriuretic peptide, troponin, free β-hCG (mRNA), and human placental lactogen (cell-free mRNA). Similarly, other proposed markers like total placental cell-free mRNA, while potentially indicative of aberrant trophoblast invasion, lack the specificity required for effective clinical application.
Etiology and Pathophysiology of PAS
The prevailing theory regarding the etiology of placenta accreta spectrum centers on defects in the endometrial–myometrial interface. These defects are thought to result in impaired decidualization in areas of uterine scarring, particularly from prior cesarean sections. This compromised interface allows for abnormally deep penetration of placental anchoring villi and trophoblast infiltration. While uterine cavity disruptions and subsequent scar tissue formation are implicated, this hypothesis does not fully explain PAS cases in nulliparous women without prior uterine surgery.
Advancing Diagnosis for OB Care: Key Modalities
Antenatal diagnosis of placenta accreta spectrum is critical for optimizing maternal and neonatal outcomes. Early diagnosis allows for planned delivery at a Level III or IV maternal care facility before labor onset or bleeding, and importantly, facilitates the avoidance of placental disruption during delivery. Obstetric ultrasonography stands as the primary diagnostic tool for antenatal PAS detection. While ultrasound features suggestive of accreta can be observed as early as the first trimester, most diagnoses occur in the second and third trimesters. Women with risk factors, such as placenta previa and prior cesarean delivery, should undergo ultrasound evaluation by experienced obstetrician–gynecologists or healthcare providers proficient in PAS diagnosis via ultrasonography.
One of the most significant ultrasound findings associated with PAS in the second and third trimesters is placenta previa, present in over 80% of accreta cases in major studies. Other grayscale ultrasound abnormalities indicative of PAS include the presence of multiple vascular lacunae within the placenta, loss of the normal hypoechoic zone between the placenta and myometrium, reduced retroplacental myometrial thickness (less than 1 mm), irregularities at the uterine serosa–bladder interface, and placental extension into the myometrium, serosa, or bladder.
Color Doppler imaging enhances diagnostic accuracy. Turbulent lacunar blood flow is a common Doppler finding in PAS. Additional Doppler signs include increased subplacental vascularity, gaps in myometrial blood flow, and vessels bridging the placenta to the uterine margin.
Although clinical risk assessment is crucial, obstetric ultrasonography demonstrates high sensitivity and specificity in PAS diagnosis. A systematic review encompassing 23 studies and 3,707 pregnancies reported an average sensitivity of 90.72% (95% CI, 87.2–93.6) and specificity of 96.94% (95% CI, 96.3–97.5%). Findings like multiple lacunae and turbulent flow are particularly strong indicators. However, it is important to recognize that ultrasound findings, even in combination, do not reliably predict the depth of placental invasion or the specific type of PAS.
Image: Ultrasound visualization of Placenta Accreta Spectrum, highlighting key diagnostic features for obstetric care.
It is essential to interpret reported accuracy rates with caution due to potential patient selection bias in studies. Many studies focus on women with pre-existing high-risk factors like previa and prior cesarean delivery, potentially leading to overestimation of ultrasound accuracy in general obstetric populations. Moreover, ultrasound abnormalities associated with PAS can also be present in normal pregnancies without PAS. A study in women with placenta previa but without PAS showed considerably lower sensitivity and specificity rates for ultrasound diagnosis. Therefore, while ultrasound is valuable, the absence of suggestive findings does not rule out PAS, and clinical risk factors remain equally important in risk assessment, especially where ultrasound expertise may be limited.
Interobserver variability in ultrasound interpretation further complicates PAS diagnosis. Studies have shown moderate agreement among experts in predicting PAS based on ultrasound findings, highlighting the need for standardized definitions of ultrasound abnormalities. Efforts towards standardization, such as those by European and international expert groups, are underway but not yet widely adopted in the United States.
Referral of women with PAS risk factors to centers with expertise in PAS imaging and diagnosis is advisable whenever feasible. Data supporting high ultrasound accuracy often originate from specialized centers, and diagnostic accuracy may not be generalizable to less experienced facilities. High rates of undiagnosed PAS suggest that expert referral could improve antenatal diagnosis rates. However, direct comparative data on diagnostic accuracy between experienced and inexperienced clinicians are lacking.
Cesarean scar pregnancy, though rare and diagnosed in the first trimester, is strongly linked to subsequent PAS if untreated. In this condition, the gestational sac implants within the uterine scar from a prior cesarean. If pregnancy continues, the risk of PAS approaches 100%. First-trimester ultrasound features of PAS include a gestational sac in the lower uterine segment and multiple irregular vascular spaces in the placental bed.
Magnetic resonance imaging (MRI) is a valuable adjunct in antenatal PAS diagnosis. MRI findings associated with PAS include dark intraplacental bands on T2-weighted images, abnormal placental or uterine bulging, disruption of the uterine-placental zone, and disorganized placental blood vessels. MRI demonstrates good accuracy for PAS prediction, with systematic reviews reporting sensitivities of 75–100% and specificities of 65–100%, comparable to ultrasonography. However, MRI studies are even more susceptible to selection bias, typically performed on patients with indeterminate ultrasound results or very high PAS risk.
It remains unclear whether MRI provides significant diagnostic improvement over ultrasonography alone. MRI may be beneficial in complex cases, such as posterior placenta previa, and in assessing the depth of invasion in suspected placenta percreta. However, definitive evidence of its added value is lacking, and MRI is more expensive, less accessible, and requires specialized interpretation. A study in women with suspected PAS indicated that MRI incorrectly confirmed or altered ultrasound-based diagnoses in a significant proportion of cases. Therefore, MRI is not the preferred initial modality for PAS evaluation.
Optimal timing and frequency of ultrasound examinations for suspected PAS are not definitively established. While monthly ultrasounds are common practice, their impact on maternal and neonatal outcomes is unproven. Early ultrasound in at-risk patients is important for accurate dating and early diagnosis. A reasonable approach includes ultrasounds around 18–20, 28–30, and 32–34 weeks of gestation in asymptomatic patients. This schedule allows for previa resolution assessment, placental location monitoring to optimize delivery timing, and potential bladder invasion detection. Cervical length, while correlated with preterm birth risk in previa, has not been extensively studied in PAS. Transvaginal ultrasonography is not contraindicated in previa and can provide valuable information on PAS, previa, and cervical length.
Women with suspected PAS, diagnosed via imaging or clinical assessment, should ideally deliver at Level III or IV centers with substantial expertise to improve outcomes. Specific indications for predelivery referrals to PAS Centers of Excellence are available in related publications. Referral soon after PAS suspicion allows for comprehensive counseling, planning, and enhanced patient comfort with the referral center and clinicians. Co-management between local physicians and Level III or IV facilities is often feasible, minimizing patient travel and family disruption.
Box 1. Key Considerations for Optimizing Placenta Accreta Spectrum Cases
Preoperative Phase:
- Maximize preoperative hemoglobin levels.
- Confirm planned delivery timing.
- Verify exact delivery location and capabilities.
- Ensure necessary preoperative consultations are completed.
- Address patient and family needs during relocation to a PAS center.
Intraoperative Phase:
- Ensure appropriate surgical expertise is available.
- Confirm intraoperative resource availability (e.g., cell-saver, point-of-care testing, surgical equipment, urologic equipment).
- Verify availability of related services (e.g., interventional radiology).
- Coordinate blood bank with surgical schedule.
Postoperative Phase:
- Engage critical care services for postoperative care.
- Identify primary service responsible for postoperative management.
Image: Multidisciplinary team approach for Placenta Accreta Spectrum management, essential for comprehensive obstetric care.
Management Strategies Following Diagnosis
Antenatal diagnosis of PAS is crucial as it enables optimized management and improved outcomes. Optimal management necessitates a standardized, multidisciplinary team approach. This team typically includes experienced obstetricians, maternal–fetal medicine specialists, pelvic surgeons (often gynecologic oncologists or female pelvic medicine and reconstructive surgeons), urologists, interventional radiologists, obstetric anesthesiologists, critical care experts, general surgeons, trauma surgeons, and neonatologists. Robust infrastructure, strong nursing leadership experienced in postpartum hemorrhage management, and access to a blood bank with massive transfusion protocols are also essential for guiding delivery location decisions.
Delivery at experienced maternity centers with coordinated care teams and resources for severe hemorrhage management improves outcomes. This is particularly relevant for women with antenatally diagnosed PAS within the framework of maternal levels of care. Regional coordination of care for high-risk women holds the potential to minimize adverse outcomes. Antenatally diagnosed PAS exemplifies conditions that greatly benefit from this coordinated care approach. While antenatal transfer and planned delivery are ideal, stabilization and transfer at delivery for newly recognized accreta can be a strategy in selected cases, contingent on maternal hemodynamic stability and local facility limitations. It is important to acknowledge that even in optimal settings, significant maternal morbidity and, rarely, mortality can occur. Management strategies for “expected” and “unexpected” PAS are further detailed below.
Management of “Expected” or Antenatally Diagnosed Placenta Accreta Spectrum
Diagnosis in the Previable Period
When PAS is diagnosed in the previable period, counseling regarding pregnancy termination options for maternal indications is important due to significant maternal morbidity and mortality risks. However, data supporting the magnitude of risk reduction through termination are limited. Termination itself in suspected PAS cases also carries risks, requiring experienced healthcare providers for counseling and procedures. ACOG Practice Bulletin No. 135, Second Trimester Abortion, provides detailed information on medical and surgical considerations for termination.
Preoperative Management and Considerations
Observational data on PAS management is increasing, but randomized clinical trial data remains limited. Management strategies are largely based on cohort studies, retrospective case series, and expert opinion. Generally agreed-upon preoperative strategies emphasize coordination and optimization.
Timing of delivery balances maternal and fetal risks and benefits. Cesarean delivery followed by immediate cesarean hysterectomy before labor onset appears to improve maternal outcomes, although optimal timing is debated. Decision analysis suggests 34 weeks gestation as optimal, considering neonatal care capabilities at this gestational age and increased bleeding risk after 36 weeks. While individual factors are relevant, a gestational window of 34 0/7–35 6/7 weeks is suggested for scheduled delivery or hysterectomy in stable patients without extenuating circumstances. Amniocentesis for pulmonary maturity is not typically needed at these gestational ages. Earlier delivery may be necessary for persistent bleeding, preeclampsia, labor, rupture of membranes, fetal compromise, or maternal comorbidities. Waiting beyond 36 0/7 weeks is not advised due to the high risk of emergent delivery for hemorrhage. Antenatal corticosteroids for lung maturation are appropriate for anticipated delivery before 37 0/7 weeks, consistent with current gestational age-based recommendations.
Planned delivery at experienced centers is strongly recommended. Preoperative coordination with anesthesiology, maternal–fetal medicine, neonatology, and expert pelvic surgeons facilitates preparation, patient counseling on cesarean hysterectomy likelihood and potential complications, anesthetic planning, and delivery preparation. A consistent multidisciplinary team improves maternal outcomes and facilitates continuous quality improvement.
Blood bank notification and collaboration are crucial due to the frequent need for large-volume transfusions, especially in difficult cross-match cases. Perioperative blood loss estimates in PAS cases vary widely. Anemia during pregnancy should be evaluated and managed. Optimizing hemoglobin levels preoperatively is logical, utilizing oral or intravenous iron replacement and erythropoietin-stimulating agents if indicated. Autologous blood donation and serial hemodilution are infrequently used and not routinely recommended.
Bed rest or pelvic rest lacks proven benefit in PAS, though historically advised, especially with bleeding. Decisions on activity modification or pelvic rest should be individualized. Antenatal bleeding, preterm labor, and preterm prelabor rupture of membranes increase unscheduled delivery risk and maternal and neonatal morbidity. Hospitalization may benefit women with these complications, as well as those with previa and bleeding episodes, or logistical factors such as distance from hospitals or referral centers. Hospitalization and activity decisions should be patient-centered.
Preoperative ureteric stent placement for bladder involvement is of unclear value and requires case-by-case evaluation, with urologic or gynecologic oncology consultation advised. Preoperative pelvic artery catheter or balloon placement for interventional radiology occlusion is also controversial. Iliac artery occlusion has shown blood loss reduction in some, but not all, series, and a small randomized trial showed no benefit. Given potential complications like arterial damage and infection, routine use is not recommended.
Intraoperative Management and Considerations
Preoperative counseling should include planned and alternative surgical strategies and potential complications. Cesarean hysterectomy with placenta left in situ is the generally accepted approach, as placental removal attempts significantly increase hemorrhage risk. Standard perioperative antibiotic prophylaxis remains applicable. Uterine incision closure followed by hysterectomy is common practice after confirming non-spontaneous placental delivery. Forced placental removal is strongly discouraged. If PAS diagnosis is uncertain preoperatively, intraoperative observation for spontaneous placental separation is appropriate, provided preparations for hysterectomy are in place. Conservative fertility-sparing approaches are discussed separately.
Dorsal lithotomy positioning facilitates vaginal and bladder access and optimal pelvic visualization. Skin incision choice is operator-dependent; vertical incisions are often preferred for better access, with wide transverse incisions like Maylard or Cherney as alternatives. Uterine inspection after peritoneal entry is crucial to assess placental invasion and location, optimizing uterine incision approach for delivery and hysterectomy. Placental avoidance in uterine incision may necessitate nontraditional incisions. Cystoscopy may be needed if bladder involvement is suspected.
Total hysterectomy is often necessary due to lower uterine segment or cervical bleeding, precluding supracervical hysterectomy in many cases. Extensive vascular engorgement and complex anatomy are typical, requiring highly experienced pelvic surgeons. Careful retroperitoneal dissection and uterine corpus devascularization near the placenta are often needed due to tissue vascularity and friability. Detailed surgical specifics are beyond this document’s scope, but procedures are best performed at Level III or IV centers with PAS expertise.
Close monitoring of volume status, urine output, blood loss, and hemodynamics is critical. Frequent communication between surgical, anesthesia, and nursing staff is essential. Hemorrhage checklists are strongly encouraged to ensure comprehensive consideration of all options. Ongoing monitoring of blood loss, hemoglobin, electrolytes, blood gas, and coagulation informs real-time replacement needs. While controlled studies on optimal blood product ratios in obstetrics are lacking, data from other surgical fields support a 1:1:1 to 1:2:4 ratio of packed red blood cells: fresh frozen plasma: platelets. Autologous cell-saver technology is a valuable option, with current filtering technologies mitigating theoretical safety concerns.
Antifibrinolytic therapy, particularly tranexamic acid, can be beneficial in PAS, especially with hemorrhage. Tranexamic acid reduces bleeding complications and mortality in non-obstetric patients and has shown maternal death reduction in postpartum hemorrhage cases in a recent large randomized trial. Adverse events in pregnant or postpartum women are not increased with tranexamic acid use, leading some authorities to recommend it for postpartum hemorrhage. The recommended dose is 1g intravenously within 3 hours of birth, with a potential second dose 0.5–23.5 hours later if bleeding persists.
Prophylactic tranexamic acid after cord clamping may reduce hemorrhage risk in PAS. A meta-analysis showed decreased bleeding with prophylactic tranexamic acid at cesarean delivery, but study designs were often flawed, and rare adverse events like renal cortical necrosis have been reported with high postpartum doses. Prophylactic use for routine cesarean delivery is not currently advised, and large studies are ongoing. Prophylactic use in PAS remains unstudied.
Other clotting factors may aid refractory bleeding. Historically, fibrinogen levels of 100 mg/dL or greater were targeted, but pregnancy may necessitate higher levels; levels below 200 mg/dL are linked to severe postpartum hemorrhage. Fibrinogen concentrates may be preferred over cryoprecipitate to reduce viral pathogen transmission risk. Fibrinogen transfusion efficacy in obstetric hemorrhage or PAS is unknown. Recombinant activated factor VIIa has been used for severe refractory postpartum hemorrhage, but carries thrombosis risk and high cost. Case series including PAS patients showed positive responses in 76–86% of cases, but thrombosis occurred in some patients. Its use in PAS should be limited to post-hysterectomy bleeding unresponsive to standard therapy.
Hypofibrinogenemia is a strong predictor of severe postpartum hemorrhage. Viscoelastic coagulation testing, such as thromboelastography or rotational thromboelastometry, can rapidly assess fibrinogen levels and hypofibrinogenemia. Rotational thromboelastometry detection of hypofibrinogenemia predicts postpartum hemorrhage severity. Systematic reviews suggest these tests reduce bleeding and transfusion in non-obstetric hemorrhage, but not morbidity or mortality. Rotational thromboelastometry’s specific utility in PAS is uncertain but has shown mortality reduction in trauma surgery and other surgical specialties.
For uncontrolled pelvic hemorrhage, hypogastric artery ligation may be considered, but its efficacy is unproven due to collateral circulation, and it can be time-consuming. Interventional radiology embolization of hypogastric arteries can be useful for persistent or uncontrolled hemorrhage, especially when no single bleeding source is identified surgically. However, it can be difficult in unstable patients and requires specialized equipment and expertise. Pelvic pressure packing and aortic compression or clamping are other methods for severe intractable pelvic hemorrhage. Pelvic packing can be effective for stabilization in acute uncontrolled hemorrhage and can be left for 24 hours with an open abdomen and ventilatory support. Aortic clamping is best reserved for experienced consultants or heroic measures due to vascular complication risks.
Other considerations in PAS hemorrhage management include maintaining patient warmth (body temperature >36°C) and avoiding acidosis, as hypothermia and acidosis impair clotting factor function. For excessive blood loss (≥1,500 mL estimated blood loss), prophylactic antibiotics should be re-dosed. Laboratory testing is critical, including baseline platelet count, prothrombin time, partial thromboplastin time, and fibrinogen levels at bleeding onset. Rapid and accurate results facilitate transfusion management. Developing protocols for rapid laboratory results or point-of-care testing is desirable.
Key principles for uncontrolled hemorrhage management include: treating the patient clinically initially without waiting for lab results, maintaining warmth, rapid transfusion, and transfusing packed red blood cells, fresh frozen plasma, and platelets in a fixed ratio in acute hemorrhage.
Postoperative Management and Considerations
PAS patients require intensive hemodynamic monitoring postoperatively, often best provided in an intensive care unit setting for hemodynamic and hemorrhagic stabilization. Close communication between operative and postoperative teams is essential. PAS patients are at increased risk of ongoing abdominopelvic bleeding, fluid overload, and other postoperative complications.
Continued vigilance for ongoing bleeding is crucial. A low threshold for reoperation is recommended for suspected ongoing bleeding. Pelvic vessel interventional radiology may be useful but not universally applicable. Clinical vigilance for complications like renal failure, liver failure, infection, unrecognized ureteral, bladder, or bowel injury, pulmonary edema, and disseminated intravascular coagulation is warranted. The possibility of Sheehan syndrome (postpartum pituitary necrosis) should also be considered.
Unexpected complications, related or unrelated to PAS, requiring unscheduled delivery can occur despite antenatal diagnosis and planning.
Management of “Unexpected” and Unplanned Intraoperative Recognition of Placenta Accreta Spectrum
Unexpected PAS recognition can occur during cesarean delivery, either before uterine incision or after fetal delivery and failed placental removal attempts, or even after vaginal delivery. Response capabilities will vary based on local resources and timing. All delivery facilities should have plans for managing or stabilizing PAS patients for transfer to higher-level facilities per institutional agreements.
If PAS is suspected based on uterine appearance before immediate delivery is mandated, the case should be paused for optimal surgical expertise arrival. Anesthesia team should be alerted, general anesthesia considered, additional intravenous access obtained, blood products ordered, and critical care personnel alerted. Cell salvage technologies should be brought into the operating suite if available. Patience is key; the primary operative team should not proceed until circumstances are optimized. If team mobilization is not feasible, stabilization and transfer should be considered if maternal and fetal stability allows.
Similar principles apply if PAS is discovered with the uterus already open after delivery. Once PAS diagnosis is confirmed and placental removal is unlikely, rapid uterine closure and proceeding to hysterectomy as judiciously as possible should be considered. Mobilization of resources should occur concurrently with hysterectomy. If the patient is stable post-delivery and the center cannot perform hysterectomy optimally, transfer should be considered, with temporizing measures like abdominal packing, tranexamic acid infusion, and transfusion with available products implemented.
Uterine Preservation and Expectant Management Strategies
Uterine preservation (conservative management) involves placenta or uteroplacental tissue removal without hysterectomy. Expectant management is defined as leaving the placenta in situ, partially or totally. Hysterectomy is the standard PAS treatment due to its life-threatening potential. Conservative or expectant approaches should be rare and individualized. Major PAS treatment complications include fertility loss, hemorrhage, and pelvic organ injury. Conservative or expectant management has been advocated to reduce these complications in select cases.
Conservative management, removing placenta or uteroplacental tissue without hysterectomy, may be feasible for focal placental adherence. Manual extraction or surgical excision followed by defect repair has achieved uterine preservation in some cases, with less blood loss than hysterectomy in small defects. En bloc removal of the uteroplacental defect followed by uterine closure may reduce blood loss and preserve fertility in larger defects. Placental removal followed by Bakri balloon insertion has also shown success in preventing hysterectomy in some series. However, these conservative approaches are reported in small case numbers, and PAS diagnosis confirmation may be uncertain in all cases, making efficacy uncertain.
Expectant management is considered investigational for more extensive PAS. It involves ligating the cord near the placenta and leaving the placenta in situ, or removing only spontaneously separated placenta before uterine closure. Data is limited to case series. In the largest series, 22% of patients required hysterectomy after expectant management, while 78% did not. Hysterectomy rates in other smaller series varied widely. In successful expectant management cases, median placental involution time was 13.5 weeks. Hysterectomies were either primary failures (within 24 hours of cesarean) or delayed failures (after 24 hours), mostly due to bleeding. Infection or febrile morbidity was common (28%), but less frequently indicated hysterectomy. Severe morbidity occurred in 6% of patients, mostly in the delayed hysterectomy group, with sepsis being common.
Expectant management success appears correlated with PAS severity. Failure rates were higher in percreta cases compared to less extensive PAS. Severe complication rates were also elevated in percreta cases. While expectant management outcomes appear promising, histologic PAS confirmation is often lacking in successful cases, and case series may include fewer women with traditional risk factors than planned cesarean hysterectomy series, potentially overestimating favorable outcome chances.
Given limited data and the standard hysterectomy approach for PAS, conservative or expectant management should be considered only for carefully selected PAS cases after detailed counseling on risks, uncertain benefits, and efficacy, and should be viewed as investigational.
Adjuncts to Conservative and Expectant Management
Adjunctive measures used with expectant management include uterine devascularization (uterine artery balloon placement, embolization, or ligation) and post-delivery methotrexate administration to reduce blood loss or hasten placental reabsorption.
Methotrexate for expectant PAS management is proposed to hasten placental involution, but its biological plausibility is questionable as third-trimester placental cell division is limited. Methotrexate carries maternal toxicity risks and is contraindicated in breastfeeding. A maternal death due to methotrexate toxicity and septic shock occurred in a large expectant management series. Given unproven benefit and potential harm, methotrexate to hasten placental resorption is not recommended.
Hysteroscopic resection of placental remnants has been proposed for expectantly managed patients with persistent placental tissue or bleeding. In a series, hysteroscopic resection resulted in hysterectomy in only one of 12 women. Multiple procedures were often needed. Hysteroscopic resection with high-intensity focused ultrasonography has also been used, but uterine perforations and hemorrhagic shock have been reported. Due to limited data, adverse events, and repeat procedure frequency, routine hysteroscopic resection, with or without high-intensity focused ultrasound, is not recommended.
Delayed Interval Hysterectomy
Delayed interval hysterectomy, a derivative of expectant management, prioritizes minimizing blood loss and tissue damage over future fertility. Placenta percreta patients are optimal candidates due to increased blood loss and tissue damage risk with primary hysterectomy at cesarean. A series of delayed hysterectomies for suspected percreta showed lower blood loss and transfusion rates compared to primary removal. Organ damage was also less frequent. Robotic hysterectomy was possible in some cases, avoiding repeat laparotomy. While preliminary data is encouraging, caution is warranted due to small case numbers and performance at a single academic center. Counseling should acknowledge efficacy uncertainty and potential risks, considering this approach investigational.
Future Fertility Considerations
Expectant PAS management appears to have minimal impact on subsequent fertility but carries a high PAS recurrence risk. A series of women monitored after expectant management showed that 30% desired subsequent pregnancy. Pregnancy success rates were reasonable, but recurrent PAS rates in subsequent pregnancies were significant (around 28%). Other series reported similar pregnancy success and increased PAS recurrence rates.
Summary and Conclusion
Placenta accreta spectrum is increasingly prevalent and associated with significant morbidity and mortality. Recognizing risk factors and utilizing antenatal imaging expertise are crucial for diagnosis for ob care. Delivery and postpartum care require a multidisciplinary team and early antepartum consultations guided by maternal levels of care. Cesarean hysterectomy is challenging and should be performed by experienced surgeons. Centers managing PAS patients must have rapid blood product mobilization capabilities. Unexpected PAS recognition during delivery necessitates immediate anesthesia team alert and consideration of pausing for expert surgical support. If expertise is lacking, stabilization and transfer are indicated. Conservative or expectant management should be considered investigational and limited to carefully selected cases after thorough counseling.
For More Information
For further resources on placenta accreta spectrum, please visit the American College of Obstetricians and Gynecologists website: www.acog.org/More-Info/PlacentaAccreta.
Disclaimer: This information is for educational purposes and should not be considered medical advice. Always consult with a qualified healthcare professional for diagnosis and treatment.
