The investigator will evaluate the detection rate for Obstetric Anal Sphincter Injuries (OASI) in primiparas having given vaginal childbirth, comparing the sensitivity of methods available in a labour ward setting for rapid detection: standard digital rectal examination (DRE) and Machine Learning-assisted electrical impedance spectroscopy (applied with the ONIRY system).

Endoanal Ultrasound (EAUS) is used as the reference standard for diagnosis' confirmation and performed within 12 weeks post-delivery.

Inclusion Criteria:

• Adult, legally competent woman
• Freely given written informed consent
• Pregnant, primigravid, admitted to labour ward and planned for vaginal delivery
• Woman in the early postpartum period (up to 1 hour postpartum) after the vaginal (spontaneous or assisted) childbirth, of a neonate of birth weight of at least 500 g or, if birth weight does not apply, gestational age of at least 22 completed weeks; if neither of the two applies, the neonate crown-heel length of at least 25cm
• Absence of any contraindication for use of machine learning-assisted electrical impedance spectroscopy
• Not currently participating or planned for any other research study related to obstetrics or proctology

Exclusion Criteria:

• Active inflammatory bowel disease affecting the perianal area
• Implants in the pelvic area
• Major malformations in perianal area or anal prolapse