What presentation in a vaginal birth should raise suspicion for Placenta Accreta Spectrum (PAS)?

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Last updated: December 8, 2025 • View editorial policy

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Retained Placenta with Minimal Bleeding and No Plane of Separation Should Raise Suspicion for PAS

In a vaginal birth, retained placenta with minimal bleeding and no plane of separation is the classic presentation that should raise suspicion for Placenta Accreta Spectrum (PAS). This presentation reflects the fundamental pathophysiology of PAS: abnormal placental adherence to the myometrium without an intervening decidual layer, preventing normal placental separation 1.

Why This Presentation is Diagnostic

The Pathophysiology Explains the Clinical Picture

  • PAS occurs when placental villi adhere directly to or invade the myometrium due to decidual deficiency, preventing the normal separation that occurs in the decidual plane 1.

  • The absence of a plane of separation is the hallmark finding because normal placentas separate through the decidual separation zone, which is absent or deficient in PAS 1.

  • Minimal bleeding distinguishes PAS from other causes of retained placenta because the placenta remains adherent and intact, preventing the massive hemorrhage that occurs when forced removal is attempted 1.

Clinical Recognition Criteria

  • Manual removal or gentle traction fails to deliver the placenta because the chorionic villi are abnormally attached to myometrial smooth muscle fibers 1.

  • The maternal surface may show disruption with missing parenchyma, absent cotyledons, or loss of the normal glistening contour when portions of the placenta are delivered 1.

  • Pathology guidelines specifically identify "manual removal, retained placenta, gross disruption of the maternal surface" as clinical indicators warranting evaluation for PAS 1.

Why Other Options Are Incorrect

Cord Avulsion After Gentle Traction

  • Cord avulsion is a mechanical complication unrelated to abnormal placental implantation and can occur with normal placentas when excessive traction is applied 1.

  • This finding does not indicate the absence of a decidual plane or abnormal myometrial adherence that defines PAS 1.

Rapid Blood Loss with Complete Placental Expulsion

  • Complete placental expulsion indicates normal separation occurred through the decidual plane, which is incompatible with the diagnosis of PAS 1.

  • Rapid blood loss with complete expulsion suggests uterine atony, genital tract trauma, or coagulopathy rather than abnormal placentation 1.

Placenta Delivers Intact Within 5 Minutes

  • Normal placental delivery within 5 minutes indicates intact decidual function and normal separation, excluding PAS 1.

  • This represents physiologic third stage of labor, not pathologic placentation 1.

Critical Management Implications

Immediate Recognition is Essential

  • Attempting forced placental removal when PAS is present causes catastrophic hemorrhage and should be avoided; the placenta should be left in situ 2, 3, 4.

  • If retained placenta with no plane of separation is encountered during vaginal delivery, immediate preparation for potential hysterectomy is warranted with mobilization of a multidisciplinary team including maternal-fetal medicine, pelvic surgeons, anesthesia, and blood bank 2, 3.

Risk Factor Assessment

  • The presence of placenta previa with prior cesarean delivery dramatically increases PAS risk: 11% with one prior cesarean, 40% with two, 61% with three, and 67% with five or more 2, 4.

  • Even without classic risk factors, retained placenta without a separation plane mandates consideration of PAS, as it can rarely occur in nulliparous women without prior uterine surgery 1.

Common Pitfalls to Avoid

  • Do not persist with manual removal attempts when no plane of separation is identified, as this converts a stable situation into life-threatening hemorrhage 2, 3.

  • Do not assume absence of bleeding excludes serious pathology; the adherent placenta prevents hemorrhage until disruption is attempted 1.

  • Ensure immediate availability of massive transfusion protocols and surgical capability when retained placenta without separation is encountered 2, 3.

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

2
Guideline

Diagnosing and Managing Placenta Accreta Spectrum

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

3
Guideline

Management and Treatment of Placenta Previa

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

4
Guideline

Classical Cesarean Section Indications and Considerations

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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