Ultrasound signs of placenta accreta spectrum (PAS): ISUOG checklist
According to ISUOG materials and related publications, ultrasound examination in suspected placenta accreta spectrum (PAS) should not only establish a diagnostic label but also stratify risk in a manner that triggers the appropriate patient management pathway. In many cases, the most valuable contribution of ultrasound is to redirect pregnancy from routine obstetric surveillance to a controlled multidisciplinary delivery strategy.
Sonographic signs suspicious for PAS
According to the literature, signs that should raise suspicion for abnormal placental implantation include:
| Sign | Significance |
|---|---|
| Low anterior placenta or placenta previa overlying a cesarean scar | Should immediately raise suspicion for abnormal placental implantation |
| Multiple irregular placental lacunae | Particularly when combined with architectural distortion—increases concern regarding the placenta accreta spectrum |
| Intracervical lacunae | Described as a sonographic marker of PAS in patients with placenta previa or low-lying placenta (di Pasquo E, Ghi T, Cali G, et al., 2020) |
Role of transvaginal approach
According to cited publications, transvaginal ultrasound is utilized in evaluating high-risk PAS patients in the third trimester, and the combination of transabdominal and transvaginal imaging helps direct clinical management of PAS cases.
Clinical significance
The primary objective of sonography in suspected placental pathology is to stratify risk in a manner that initiates the appropriate management pathway. Specific threshold criteria for assessing PAS severity in the provided excerpts are not detailed [verification needed].
Standardization of ultrasound signs
Standardization of ultrasound signs associated with PAS is reflected in a modified Delphi study (Jauniaux E, D'Antonio F, Bhide A, et al. Modified Delphi study of ultrasound signs associated with placenta accreta spectrum. Ultrasound Obstet Gynecol 2023; 61: 518–525). The specific list of consensus-based signs is not detailed in the provided excerpts [verification needed].
Frequently asked questions
Which signs should immediately raise suspicion for PAS?
Low anterior placenta or placenta previa located over a scar from previous cesarean delivery should immediately raise suspicion for abnormal placental implantation.
How should placental lacunae be assessed?
Multiple irregular placental lacunae, particularly when combined with architectural distortion, increase concern regarding the placenta accreta spectrum. Intracervical lacunae are also described as a marker of PAS in patients with placenta previa or low-lying placenta.
Is transvaginal imaging necessary?
Yes, according to cited evidence, transvaginal ultrasound is used in evaluating high-risk PAS patients in the third trimester; combination of transabdominal and transvaginal imaging helps direct clinical management.
What is the primary objective of ultrasound in suspected PAS?
To stratify risk in a manner that redirects pregnancy from routine surveillance to a controlled multidisciplinary delivery strategy; the diagnostic label itself is secondary.
Is there a consensus-based list of ultrasound signs for PAS?
Sign standardization is reflected in a modified Delphi study (Jauniaux E et al., Ultrasound Obstet Gynecol 2023; 61: 518–525); however, the complete list of consensus signs is not detailed in the available excerpts [verification needed].