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OB
CMECNE

Placenta Accreta Spectrum Disorder: Definitions and Management

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Learning Objectives and CME/Disclosure Information

This activity is intended for healthcare providers delivering care to women and their families.

After completing this activity, the participant should be better able to:

1. Recall the risks of placenta accreta when placenta previa is present in patients with prior cesarean sections
2. Discuss the use of MRI to diagnose placenta accreta

Estimated time to complete activity: 0.25 hours

Faculty:

Susan J. Gross, MD, FRCSC, FACOG, FACMG
President and CEO, The ObG Project

Disclosure of Conflicts of Interest

Postgraduate Institute for Medicine (PIM) requires faculty, planners, and others in control of educational content to disclose all their financial relationships with ineligible companies. All identified conflicts of interest (COI) are thoroughly vetted and mitigated according to PIM policy. PIM is committed to providing its learners with high quality accredited continuing education activities and related materials that promote improvements or quality in healthcare and not a specific proprietary business interest of an ineligible company.

The PIM planners and others have nothing to disclose. The OBG Project planners and others have nothing to disclose.

Faculty: Susan J. Gross, MD, receives consulting fees from Cradle Genomics, and has financial interest in The ObG Project, Inc.

Planners and Managers: The PIM planners and managers, Trace Hutchison, PharmD, Samantha Mattiucci, PharmD, CHCP, Judi Smelker-Mitchek, MBA, MSN, RN, and Jan Schultz, MSN, RN, CHCP have nothing to disclose.

Method of Participation and Request for Credit

Fees for participating and receiving CME credit for this activity are as posted on The ObG Project website. During the period from Dec 31 2017 through Jan 25 2023, participants must read the learning objectives and faculty disclosures and study the educational activity.

If you wish to receive acknowledgment for completing this activity, please complete the post-test and evaluation. Upon registering and successfully completing the post-test with a score of 100% and the activity evaluation, your certificate will be made available immediately.

For Pharmacists: Upon successfully completing the post-test with a score of 100% and the activity evaluation form, transcript information will be sent to the NABP CPE Monitor Service within 4 weeks.

Joint Accreditation Statement

In support of improving patient care, this activity has been planned and implemented by the Postgraduate Institute for Medicine and The ObG Project. Postgraduate Institute for Medicine is jointly accredited by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team.

Physician Continuing Medical Education

Postgraduate Institute for Medicine designates this enduring material for a maximum of 0.25 AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Continuing Nursing Education

The maximum number of hours awarded for this Continuing Nursing Education activity is 0.2 contact hours.

Read Disclaimer & Fine Print

In normal circumstances, the trophoblast stops invading the uterus when Nitabuch’s layer is reached in the decidua. In cases of accreta, the trophoblast invades the myometrium due to a deficient or damaged Nitabuch’s layer. Placenta accreta occurs within a spectrum of disorders now referred to as ‘Placenta Accreta Spectrum’ (formerly ‘Morbidly Adherent Placenta’)

  • Placenta Accreta: trophoblasts attach to the myometrium without intervening decidua
  • Placenta Increta: trophoblasts invade through the myometrium
  • Placenta Percreta: trophoblasts move through the myometrium and invade beyond the serosa and into surrounding tissues

Clinical Actions:

  • It is advisable to refer women with clinical or ultrasound risk factors for placenta accreta to a center of excellence for evaluation, confirmation and delivery (Grade 1B – Strong recommendation – Moderate quality evidence)
    • Arrange for delivery at a level III or IV center with experience if possible
  • Optimal timing of delivery
    • Without bleeding or contractions can have a planned cesarean delivery at 34w0d – 35w6d (Grade 1A – Strong recommendation – High quality evidence)
    •  Consider delivery around 34w0d for women with the following (International Society for Abnormally – Invasive Placenta; Grade D recommendation)
      • History of previous preterm birth | Multiple episodes of small amounts of vaginal bleeding | A single episode of a significant amount of vaginal bleeding | PPROM
  • Corticosteroids
    • Administer corticosteroids to all women with suspected accreta if (SMFM recommendation Grade 1A)
      • Delivery expected within 7 days and meets gestational age criteria
      • Antenatal corticosteroids have not previously been administered
    • Do not delay delivery in the setting of active hemorrhage for the purpose of administering antenatal corticosteroids (SMFM recommendation Grade 1B)
  • Hospitalization vs outpatient care
    • Outpatient: In the absence of bleeding and any other symptoms or complications, there is limited evidence that hospitalization is of benefit
      • If outpatient management is elected, there must be a system in place for the patient to rapidly return to the hospital in case of bleeding, contractions or complications
    • Inpatient: women with preterm labor, PPROM or bleeding are “most likely to benefit” from hospitalization
  • Hgb levels (FIGO, RCOG and International Society for Abnormally – Invasive Placenta)
    •  If <110 g/L (11 g/dL) before 28 weeks or <105 g/L (10.5 g/dL) after 28 weeks
      • Work up for anemia and if indicated, begin iron supplementation (oral or intravenous) to optimize levels

Management

  • In the setting of hemorrhage, the following blood product ratio range is recommended based on data from other surgical specialties (Grade 1A)
    • Packed RBC:FFP:Platelet = 1:1:1 to 1:2:4
  • High Risk management can be found in the ‘SMFM Guidelines’ and ‘Obstetric Care Consensus’ and International Society for Abnormally – Invasive Placenta ‘Evidence Based Guidelines’ (see ‘Learn More – Primary Sources’ below)
  • The International Society for Abnormally – Invasive Placenta does make the following recommendations (Grade D evidence)
    • Ureteral stents may be used, but insufficient evidence to recommend for routine use with primary benefit likely in the case of percreta
    • No evidence that routine vertical skin incision is superior to transverse and therefore base decision on
      • Placental location | Degree of possible invasion suspected |  Complication risk | Maternal body habitus | Gestational age | Preference of the surgeon
    • Avoid placental transection upon uterine incision even if this entails an upper segment or fundal incision
    • Ultrasound mapping (sterile) “of the exposed uterus should be used, where possible, to locate the placental edge and assist decision making regarding the uterine incision site”
  • Uterine preservation
    • Conservative management: Removal of placenta or uteroplacental tissue and no hysterectomy
      • Focal placental adherence
      • Followed by repair of uterine defect
      • Data limited
    • Expectant management: Placenta left in situ
      • More extensive adherence
      • Data limited
    • ACOG/SMFM obstetric care consensus (2018) states

Conservative management or expectant management should be considered only for carefully selected cases of Placenta Accreta Spectrum after detailed counseling about the risks, uncertain benefits, and efficacy and should be considered investigational (Grade 2C – Weak recommendation – Low quality evidence)

Synopsis:

The incidence of placenta accreta has been increasing from 0.8/1000 in the 1980’s to 3/1000 deliveries. The risk increases with the increasing number of cesarean deliveries. This is especially true for women with placenta previa and prior cesarean sections. Mortality may be as high as 6 to 7%. Maternal complications are primarily the result of massive hemorrhage which can lead to DIC, multi-organ failure, hysterectomy, thromboembolism and death. Neonatal complications are the result of prematurity. The average gestational age at delivery of a pregnancy with Accreta is 34-36 weeks.

Key Points:

If previa is present

  • 3% risk of accreta with the 1st cesarean section
  • 11% risk of accreta at the 2nd cesarean section
  • 40% risk of accreta at the 3rd cesarean section
  • 61% risk of accreta at the 4th cesarean section
  • 67% risk of accreta at the 5th cesarean section

Risk factors

  • Prior cesarean section
  • Uterine curettage
  • Prior myomectomy
  • Placenta previa
  • Short inter-pregnancy interval
  • IVF
  • Multiparity
  • Prior pelvic radiation
  • Endometrial ablation
  • Maternal smoking

The mainstay of antenatal diagnosis is ultrasound

Note: Absence of ultrasound findings does not mean the patient does not have accreta | Clinical risk factors should be weighted equally compared to sonographic findings (Grade 1A)

  • First trimester findings include
    • Cesarean scar pregnancy (risk may approach 100% if pregnancy allowed to continue)
    • Gestational sac implanted in the lower uterine segment
    • Irregular vascular spaces in the placental bed
    • Loss of retroplacental-myometrial zone
  • Second and third trimester findings include
    • placenta previa (present in 80% of accreta)
    • loss of retroplacental-myometrial hypoechoic zone
    • multiple vascular lacunae
    • placental villi extension into the myometrium and beyond
    • interruption of the uterine serosal/ bladder interface
    • decreased retroplacental myometrial thickness (<1mm)

Role of MRI

  • MRI has sensitivities (75%-100%) and specificities (65%-100%) approaching that of ultrasound, but has not been shown to improve the diagnostic accuracy of accreta compared to ultrasound (Grade 1B)

Learn More – Primary Sources:

ACOG/SMFM Obstetric Care Consensus: Placenta Accreta Spectrum

Society for Maternal-Fetal Medicine (SMFM) Consult Series #44: management of bleeding in the late preterm period

SMFM Publications & Guidelines: Placenta Accreta

ACOG SMFM Committee Opinion 831: Medically Indicated Late-Preterm and Early-Preterm Deliveries

Abnormal Placentation: Placenta Previa, Vasa Previa, and Placenta Accreta

Evidence-based guidelines for the management of abnormally-invasive placenta: recommendations from the International Society for AIP

RCOG: Placenta Praevia and Placenta Accreta – Diagnosis and Management

FIGO consensus guidelines on placenta accreta spectrum disorders: Nonconservative surgical management

FIGO consensus guidelines on placenta accreta spectrum disorders: Conservative management

Evidence-based guidelines for the management of abnormally invasive placenta recommendations from the International Society for Abnormally Invasive Placenta

SOGC Guideline 383-Screening, Diagnosis, and Management of Placenta Accreta Spectrum Disorders

Special Report of the Society for Maternal- Fetal Medicine Placenta Accreta Spectrum Ultrasound Marker Task Force: Consensus on definition of markers and approach to the ultrasound examination in pregnancies at risk for placenta accreta spectrum

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Related ObG Topics:

Placenta Previa – Nomenclature, Diagnosis and Clinical Management
Vasa Previa: Diagnosis and Management
Does MRI Help or Hurt When Making a Diagnosis of Placenta Accreta?
Antenatal Corticosteroids – When to Administer?
Ultrasound for Previa Accreta in Women with Prior C-Section
Does Intra-Aortic Balloon Improve Outcomes during Surgery for Adherent Placenta
ACOG Recommendations: When to Deliver Medically Complicated Pregnancies

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This educational activity may contain discussion of published and/or investigational uses of agents that are not indicated by the FDA. The planners of this activity do not recommend the use of any agent outside of the labeled indications.

The opinions expressed in the educational activity are those of the faculty and do not necessarily represent the views of the planners. Please refer to the official prescribing information for each product for discussion of approved indications, contraindications, and warnings.

Disclaimer

Participants have an implied responsibility to use the newly acquired information to enhance patient outcomes and their own professional development. The information
presented in this activity is not meant to serve as a guideline for patient management. Any procedures, medications, or other courses of diagnosis or treatment discussed or suggested in this activity should not be used by clinicians without evaluation of their patient’s conditions and possible contraindications and/or dangers in use, review of any applicable manufacturer’s product information, and comparison with recommendations of other authorities.

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