Analysis of Risk Scoring for Placenta Accreta Spectrum and Its Impact on Maternal and Fetal Outcomes

Placenta accreta spectrum (PAS) disorders, characterized by abnormal adherence or invasion of the placenta into the myometrium, are associated with significant maternal and neonatal morbidity. Early identification of high-risk cases is essential to optimize delivery planning and reduce adverse outcomes. The Placenta Accreta Index (PAI), integrating clinical history and ultrasound parameters, has been proposed as a predictive tool for PAS. This study aimed to evaluate the diagnostic accuracy of the PAI in predicting PAS and its utility in anticipating maternal and neonatal outcomes.

A prospective observational study was conducted on 150 pregnant women at risk for PAS. A single experienced sonographer performed all ultrasound evaluations and PAI scoring to minimize observer bias. The PAI incorporated the number of prior cesarean sections, placental lacunae grade, sagittal myometrial thickness, anterior placenta previa, and bridging vessels. A standardized management protocol was followed: antenatal corticosteroids for fetal lung maturity, magnesium sulfate for neuroprotection when <34 weeks, and multidisciplinary team involvement (obstetricians, anesthetists, neonatologists, and blood bank). MRI or Doppler studies were used selectively to confirm placental invasion depth, and delivery timing (34-36 weeks or earlier for antepartum bleeding) was guided by imaging and clinical stability. Intraoperative findings and histopathological examination (HPE) served as reference standards. Maternal and neonatal outcomes were recorded.

Among 150 participants, the placenta was posterior in 84 (56%), anterior in 33 (22%), low-lying in 18 (12%), and fundal in 15 (10%). Placental lacunae were most commonly Grade 2 (49, 32.7%), and myometrial thickness <1 mm was observed in 58 (38.7%). Placenta previa was present in 105 (70%) women. HPE findings revealed a normal placenta in 142 (94.7%), absence of decidua with thin Nitabuch's layer in 4 (2.7%), thin Nitabuch's layer in 3 (2%), and villi directly contacting myometrium in 1 (0.7%). The PAI demonstrated sensitivity 100% (95% CI: 2.5-100), specificity 97.3% (95% CI: 92.8-99.2), positive predictive value 20% (95% CI: 3.6-62.4), negative predictive value 100%(95% CI: 97.4-100), and overall diagnostic accuracy 97.3% (95% CI: 92.9-99.2). Maternal outcomes were favourable in 145 (96.7%) cases; one woman (0.7%) required hysterectomy, and four (2.7%) had excessive bleeding managed conservatively.

PAI is a reliable, non-invasive tool for identifying women at high risk for PAS. High PAI scores can guide prenatal counselling, delivery planning, and resource allocation, while low scores effectively rule out severe placental invasion, supporting safer conservative management. The use of PAI may have the potential to improve maternal and neonatal outcomes in pregnancies complicated by PAS.