What are the key ultrasound findings that suggest a diagnosis of placenta accreta spectrum in a pregnant patient?

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 17 August 2025 Guideline-Aligned (High Confidence) Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

The key ultrasound findings that suggest a diagnosis of placenta accreta spectrum (PAS) in a pregnant patient include several characteristic features.

One significant finding is the loss of the clear retroplacental zone or space . The presence of multiple placental lacunae, which are irregular vascular spaces within the placenta, is another strong indicator . Additionally, ultrasound may reveal thinning, disruption, or irregularity of the myometrial-bladder interface or uterine serosa-bladder interface . Increased vascularity at the myometrial-bladder interface is also a suggestive sign . The visualization of bridging vessels, which extend from the placenta into the myometrium or beyond, further supports a diagnosis of PAS . On color Doppler, turbulent blood flow within the lacunae can also be observed .

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