Objective: To evaluate the clinical performance and safety of the ONIRY system for obstetric anal sphincter injuries (OASI) detection versus three-dimensional endoanal ultrasound (EAUS). Design: A prospective, comparative, multicentre, international study. Setting: Poland, Czechia, Slovakia, and Spain. Population: 152 women between the first moments up to 8 weeks after vaginal delivery. Methods: 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. Main Outcome Measures: Accuracy, sensitivity, and specificity. Results: 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. Conclusion: The ML-assisted impedance spectroscopy appears to be a high-performance and safe method for rapid OASI detection, complementing digital rectal examination in obstetric settings. Funding: The study was financed by the Polish National Centre for Research and Development (POIR.01.01.01-00-0726/18).

K.B. is a founder and management board member at OASIS Diagnostics, an author of the related patent and R&D strategy, independent consultant, and trainer of Takeda. M.M., M.R., K.K., and P.I. are staff of OASIS Diagnostics. A.S. is an independent consultant of Ethicon, Takeda, Pfizer, Sofar. M.UM. is an independent consultant of Regen Lab. H.H., P.J., M.UM., E.D., and E.GD. received remuneration as a study investigator. H.H., C.R., and A.S. are independent consultants and members of the OASIS Diagnostics' Scientific Advisory Board. Others declare no conflicts of interest.

NCT04903977

The study was funded by the European Union as part of the Fast Track program, conducted in Poland by the National Centre for Research and Development (POIR.01.00.01-00-0726/18).

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The study was approved by the ethics committees respective for each study site: on 19 March 2021 by Ethics Committee of the Institute for Maternal and Child Care (no. 1/19.03.2021), on 27 April 2021 by Ethics Committee for Research with Medicines of the Health Areas of Leon and Bierzo (no. 2186), on 9 June 2021 by Ethics Committee of the University Hospital of Brno (no. 47/21Zdrav.), on 14 October 2021 by Ethics Committee at the Regional Medical Chamber in Warsaw (no. KB/1362/21) and on 25 July 2022 by Ethics Committee at AGEL Hospital Kosice-Saca (no. ONIRY 3/2/2020).

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