Impedance spectroscopy – new method in diagnostic of OASI
The ONIRY method, utilizing machine learning-assisted impedance spectroscopy, offers a highly accurate, non-invasive diagnostic tool for detecting obstetric anal sphincter injuries (OASI).
Electrical impedance applications in medicine are well known and used in disciplines such as body composition, fluid, cardiac monitoring, and gastroesophageal reflux disease.
Impedance in medicine refers to the resistance that body tissues provide to the flow of electrical current. In medical contexts, this term is often used in diagnostic methods such as bioelectrical impedance analysis (BIA) or bioimpedance.
The ONIRY method, utilizing machine learning-assisted impedance spectroscopy, offers a highly accurate, non-invasive diagnostic tool for detecting obstetric anal sphincter injuries (OASI). This technique measures electrical impedance in tissues, achieving 90% accuracy in distinguishing between healthy and affected areas, providing valuable support in postpartum care. The method offers quick results, with the ability to identify the location of potential injuries and guide further medical intervention.
CLINICAL performance of ONIRY method
Machine Learning – Assisted Impedance Spectroscopy vs. EAUS
Final ML Model for ONIRY (Post Data Cleaning):
- Accuracy: 90.0 ± 0.4%
- Sensitivity: 90.0 ± 1.2%
- Specificity: 90.0 ± 0.7%
K. Borycka, M. Młyńczak, M. Rosoł, et. al.: Detection of obstetric anal sphincter injuries using machine learning-assisted impedance spectroscopy: a prospective, comparative, multicentre clinical study, Scientific Reports, 15(1):7522, 2025; https://www.nature.com/articles/s41598-025-92392-z
How ONIRY works?
The method is based on measuring the electrical impedance of tissues, capable of distinguishing between ‘healthy’ and ‘pathology-affected’ tissue.
As the differences between pathologies are not always sufficiently distinguishable, the ONIRY method has involved Machine Learning in achieving precision in differentiating pathologies of the perianal area.
As a result of these advancements, the ONIRY method demonstrates high clinical performance, achieving 90% accuracy in differentiating pathologies of the perianal area.
The ONIRY probe’s electrodes are designed to measure in a dozen configurations.
Each measurement run comprises impedance measurements of every sector, allowing examination of a full 360-degree circumference at different frequencies (range 1 – 100 kHz).
The ONIRY probe showcases its versatility and comprehensive data collection during a 1-minute test by summarizing the extensive range of configurations and frequencies.
Analysis steps:
1
Impedance data measurement
2
Impedance data parameterisation
3
Launching Machine Learning models (trained on clinical data)
4
Presenting the result as “PASS” (no OASI) or “REFER” (OASI detected) and suggesting the location of the injury.
The ‘PASS’ result indicates no OASI detected.
You can assure your patient that there is no injury, so she can safely embrace motherhood.
The ‘REFER’ result suggests potential OASIs.
If data collected by ONIRY indicate a particular location of OASI, a corresponding section of the anal canal circumference will be further highlighted in red.
The ‘REFER’ result suggests potential OASIs.
If no specific location is suggested, the entire anal canal circumference will be depicted in the form of an orange ring.
Diagnosis enhanced
The potential of electrical bioimpedance in detecting OASI makes it easier to examine women after vaginal delivery. This technology provides valuable support for healthcare professionals, overcoming limitations posed by the difficult examination environment, swelling, tiredness, and lack of experience. With 90% accuracy of ONIRY, we believe that this technology can significantly support diagnosing anal sphincter damage during childbirth, enabling new mothers to fully embrace motherhood.
