Placenta Accreta Spectrum (PAS) Ultrasound/MRI Scoring

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Checklist of accepted sonographic and MRI signs of placenta accreta spectrum plus the major clinical risk pairing (previa after cesarean). Produces a qualitative suspicion tier from the number and type of findings—not a validated numeric score.

Also searched as: abnormally invasive placenta · previa · obstetric · women · pregnancy

Sonographic / MRI signs suggestive of PAS

Select all signs present on ultrasound and/or MRI. Definitions follow SMFM/ACOG consensus descriptors; MRI items are adjunctive descriptors used in practice.

Major clinical risk: placenta previa (or persistent low-lying placenta) with prior cesarean delivery

This pairing is the strongest clinical predictor of PAS and markedly raises pretest probability even when imaging is limited.

Information

Incomplete input

Please provide: at least one imaging sign, or an answer for the major clinical risk factor (previa / low-lying placenta with prior cesarean).

How this tool works

Prenatal suspicion of placenta accreta spectrum (PAS) rests on clinical risk factors and imaging markers. The strongest clinical association is placenta previa (or low-lying placenta) with prior cesarean delivery. Gray-scale and color Doppler ultrasound markers standardized by the SMFM PAS Ultrasound Marker Task Force and reflected in ACOG/SMFM guidance include loss of the retroplacental clear zone, myometrial thinning (<1 mm), bladder-wall or uterovesical-interface irregularity, placental lacunae (especially with turbulent flow), hypervascularity at the uterovesical/retroplacental interface, bridging vessels, and exophytic mass or extrauterine placental tissue. MRI adjuncts commonly reported include dark T2 intraplacental bands and placental bulge. There is no single universally agreed additive point score; interpretation is qualitative and must integrate pretest risk, gestational age, and multidisciplinary review. Absence of imaging signs does not exclude PAS when clinical risk is high.

References

Implemented from the cited published sources. Educational use only; confirm against current guidelines before clinical use.

Clinical questions that use this

Vetting guides that reach for this tool.

Suspected placenta accreta spectrum

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