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’)
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)
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.
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)
ACOG/SMFM Obstetric Care Consensus 7: Placenta Accreta Spectrum
SMFM Consult Series #44: management of bleeding in the late preterm period
ACOG SMFM Committee Opinion 831: Medically Indicated Late-Preterm and Early-Preterm Deliveries
Abnormal Placentation: Placenta Previa, Vasa Previa, and Placenta Accreta
RCOG: Placenta Praevia and Placenta Accreta – Diagnosis and Management
FIGO consensus guidelines on placenta accreta spectrum disorders: Conservative management
SOGC Guideline 383-Screening, Diagnosis, and Management of Placenta Accreta Spectrum Disorders
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