Predicting Placenta Accreta Spectrum: Validation of the Placenta Accreta Index

Area of Science:

• Maternal-fetal medicine
• Diagnostic imaging in obstetrics

Background:

• The incidence of placenta accreta spectrum (PAS) has increased significantly, coinciding with higher rates of cesarean delivery (CD).
• Accurate prenatal diagnosis of PAS is crucial for improving maternal outcomes and surgical planning.
• The Placenta Accreta Index (PAI) offers a standardized method for prenatal PAS diagnosis using clinical risk and ultrasound (US) findings.

Purpose of the Study:

• To validate the Placenta Accreta Index (PAI) for predicting placenta accreta spectrum (PAS) in pregnancies with a history of cesarean delivery (CD).

Main Methods:

• A retrospective cohort study included 194 pregnancies with prior CD and third-trimester ultrasound diagnosis of placenta previa or low-lying placenta.
• Two blinded physicians applied the PAI to third-trimester ultrasound images.
• Surgical and pathological findings were reviewed to confirm PAS diagnosis based on International Federation of Gynecology and Obstetrics criteria.

Main Results:

• The PAI demonstrated a sensitivity of 87%, specificity of 77%, positive predictive value of 72%, and negative predictive value of 90% for PAS diagnosis with a threshold greater than 4.
• Of 194 women, 92 (47%) underwent cesarean hysterectomy and 97 (50%) had a CD.
• Histological confirmation of PAS was found in 85% of hysterectomy cases.

Conclusions:

• The Placenta Accreta Index (PAI) is a valuable tool for the prenatal prediction of placenta accreta spectrum (PAS).
• Standardized application of the PAI in conjunction with ultrasound diagnosis aids in the accurate prenatal assessment of PAS risk.