Since its introduction in the early 1990s, endoanal sonography has become the mainstay of morphologic assessment of the anal canal and sphincter, especially for obstetric anal sphincter trauma. Lack of availability of suitable systems and the invasive nature of the method have limited uptake and clinical utility. More recently, exoanal or transperineal/translabial tomographic imaging has been developed as a noninvasive alternative. This pictorial overview aims to introduce the reader to this new diagnostic modality and to demonstrate common findings in asymptomatic and symptomatic women.
Keywords: 4-dimensional sonography; anal sphincter; birth trauma; exoanal sonography; fecal incontinence; gynecologic ultrasound; pelvic floor.
© 2017 by the American Institute of Ultrasound in Medicine.