Imaging of Obstetric and Nonobstetric Perineal Trauma: MRI Anatomy, Patterns, and Reporting

Contemporary understanding of perineal trauma is primarily derived from obstetric literature, where perineal tears have been extensively researched, as childbirth remains the most common cause of perineal tears. Accurate diagnosis typically requires a high index of clinical suspicion, with transperineal or endocavitary US being the initial imaging modality. In comparison, nonobstetric mechanisms of perineal trauma are secondary to inadvertent surgical injury and are managed by surgeons. Consequently, many surgical approaches used for management of iatrogenic perineal tears have been adapted from obstetric practice. In addition, complex perineal trauma as part of multisystemic injury is increasingly encountered in urbanized societies, often due to high-energy impact mechanisms. Long-term complications include anal incontinence, pelvic organ prolapse, urinary incontinence, and sexual dysfunction. The radiologist's role in the early management of perineal trauma may be limited to multisystemic injuries, but radiologic involvement is encouraged in patients with complicated perineal trauma. MRI is not routinely used for early diagnosis of perineal tears; however, it often allows detection of occult tears during evaluation of women presenting with pelvic floor symptoms. In complex perineal trauma, particularly when deformity and scarring render endoluminal US unfeasible, MRI allows reliable anatomic assessment before reconstructive surgery. For radiologists, a thorough understanding of perineal anatomy, along with injury mechanisms and a structured checklist, facilitates accurate diagnosis, which is fundamental for surgical planning. This review explores perineal anatomy, various mechanisms of obstetric and nonobstetric perineal trauma, associated imaging findings, and the growing role of MRI in their assessment. ^©RSNA, 2026.