Evaluation of the Topographic Classification of Placenta Accreta Spectrum: Protocol for an Ongoing Prospective Multicenter Study

Abstract

Background Placenta accreta spectrum (PAS) is a life-threatening obstetric condition associated with increasing cesarean delivery rates worldwide. Existing classifications, such as the World Health Organization International Statistical Classification of Diseases and Health-Related Problems and the International Federation of Gynecology and Obstetrics system, describe depth of invasion and histopathological features but do not adequately predict surgical outcomes or guide individualized management.The PAS topographic classification describes the anatomical extent of uterine wall remodeling and the presence of uterovesical adhesions, allowing surgical teams to anticipate intraoperative complexity, organ involvement, and appropriate therapeutic strategies. Although successfully applied in selected centers, its broader evaluation across diverse healthcare settings is lacking. Methods We designed a prospective, multicenter, international cohort study enrolling patients with a high prenatal suspicion of PAS. Eligible patients are aged >= 18 years, undergoing surgery after 20 weeks' gestation, and managed by multidisciplinary PAS teams familiar with the topographic classification. Standardized prenatal ultrasound staging and intraoperative surgical staging are required, with photographic and video documentation. Surgical strategies include one-step conservative surgery, total hysterectomy, and modified subtotal hysterectomy, guided by intraoperative classification.The primary outcome is intraoperative blood loss, measured using a standardized protocol. Secondary outcomes include intraoperative complications, operative time, treatment type, and usability assessments of the classification through structured surveys. Data are collected in REDCap with external review of imaging records.Discussion This study will provide the first prospective, multicenter evaluation of the PAS topographic classification, assessing its correlation with clinical outcomes and its feasibility across hospitals with varying resources and surgical expertise. Preliminary results indicate successful implementation in both high-and low-volume centers, with promising adoption of prenatal ultrasound staging and surgical protocols.The collaborative, image-based, and open-access methodology aims to strengthen the reliability of PAS research by harmonizing surgical strategies and allowing external supervision. Ultimately, this project will generate robust multicenter data to inform individualized management strategies and support the integration of the topographic classification into routine clinical practice worldwide. Trial registration ClinicalTrials.gov Identifier: NCT05922397. Registered on 21 May 2023.