Predictive Value of the Soluble fms-Like Tyrosine Kinase-1/Placental Growth Factor Ratio in Preeclampsia and Placenta Accreta Spectrum: A Prospective Observational Study

Background: Certain placentation disorders, such as preeclampsia and placenta accreta spectrum (PAS), are prevalent causes of maternal and fetal morbidity. Angiogenic biomarkers, including soluble fms-like tyrosine kinase-1 (sFlt-1), placental growth factor (PlGF), and the sFlt-1/PlGF ratio, are increasingly used in the evaluation of preeclampsia; however, their relevance in PAS remains unclear. Objective: To evaluate the diagnostic performance of sFlt-1, PlGF, and the sFlt-1/PlGF ratio for preeclampsia and explore their potential diagnostic utility in PAS. Methodology: This prospective observational study was conducted at a tertiary care hospital in North India from June 2024 to June 2025. A total of 200 antenatal women at 20-37 weeks of gestation were recruited and divided into three groups: preeclampsia, PAS, and a comparison group without preeclampsia or PAS. Serum levels of sFlt-1 and PlGF were determined by electrochemiluminescence immunoassay (ECL), and the ratio sFlt-1/PlGF was calculated. The optimum cutoff values were determined by the receiver operating characteristic curve, and the diagnostic performance was evaluated. Results: Of the 200 participants, 57 (28.5%) had preeclampsia, 16 (8.0%) had PAS, and 127 (63.5%) had neither condition. At a cutoff of 77.65, the sFlt-1/PlGF ratio performed the best, with an area under the curve of 0.902 for preeclampsia, an accuracy of 88.0%, a positive predictive value (PPV) of 80.7%, a negative predictive value (NPV) of 91.3%, and a sensitivity of 80.7%. PAS had a high NPV of 97.1%, a low PPV of 18.7%, a high sensitivity of 87.5%, a low specificity of 52.0%, an accuracy of 55.9%, and an area under the curve (AUC) of 0.678. Conclusions: The sFlt-1/PlGF ratio was an excellent discriminator of preeclampsia and could be used to help identify and stratify at-risk individuals. It is not very specific and has a low PPV in PAS, meaning that it should not be used as a surrogate for imaging-based diagnosis and clinical risk assessment in PAS.