To evaluate the clinical performance and safety of the ONIRY system for obstetric anal sphincter injuries (OASI) detection versus three-dimensional endoanal ultrasound (EAUS). A prospective, comparative, multicentre, international study. Poland, Czechia, Slovakia, and Spain. 152 women between the first moments up to 8 weeks after vaginal delivery. Participants underwent EAUS and were allocated to groups based on OASIS classification: A (no perineal tear), B (1st or 2nd degree tear), or C (3rd or 4th degree, anal sphincters affected). Electric impedance was measured in the anal canal using the ONIRY system. The primary endpoint was the diagnostic outcome of impedance spectroscopy versus EAUS. Adverse events were collected. Part II involved in silico modelling and 10-time 10-fold cross-validation for automated analysis. Accuracy, sensitivity, and specificity. 30 women were allocated to group A, 61 to group B, and 61 to group C. The diagnostic outcome was determined for 147 participants. The accuracy, sensitivity, and specificity of the ML-assisted impedance spectroscopy were 87.0 ± 0.5%, 90.6 ± 2.0%, and 84.6 ± 1.9%, respectively, compared with EAUS. After data cleaning, the performance metrics of the proposed final ML model for ONIRY were: 90.0 ± 0.4%, 90.0 ± 1.2%, and 90.0 ± 0.7%, respectively. No adverse device effects or deficiencies were observed. By enabling early identification of sphincter injuries, ML-assisted impedance spectroscopy facilitates timely diagnosis and intervention, potentially reducing long-term complications such as faecal incontinence. Its rapid, bedside application in obstetric settings supports immediate postpartum care, complementing digital rectal examination and optimizing clinical decision-making.

3rd Medical Faculty Charles University Prague Czech Republic

Department of Biomedical Sciences Humanitas University Via Rita Levi Montalcini 4 20072 Pieve Emanuele Milan Italy

Department of General and Colorectal Surgery Medical University of Lodz Lodz Poland

Department of General Surgery Faculty of Medicine Lazarski University Warsaw Poland

Department of Gynaecology and Obstetrics Faculty of Medicine Univerzita Pavla Jozefa Šafárika Košice Slovakia

Department of Health Sciences Medical Faculty Masaryk University Brno Czech Republic

Department of Obstetrics and Gynaecology Complejo Asistencial Universitario de Leon León Spain

Department of Obstetrics and Gynaecology Solec Hospital Warsaw Poland

Department of Obstetrics and Gynaecology University Hospital Brno and Medical Faculty Masaryk University Brno Czech Republic

Department of Radiology National Institute of Geriatrics Rheumatology and Rehabilitation Warsaw Poland

Faculty of Mechatronics Institute of Metrology and Biomedical Engineering Warsaw University of Technology Warsaw Poland

Institute for the Care of Mother and Child Prague Czech Republic

IRCCS Humanitas Research Hospital via Manzoni 56 20089 Rozzano Milan Italy

OASIS Diagnostics R and D of Medical Technology Warsaw Poland

Proctology and Pelvic Floor Surgery Unit Isola Tiberina Hospital Gemelli Isola Catholic University Rome Italy

Ultrasound Department Warsaw Medical University Warsaw Poland

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