Endoanal ultrasonography in fecal incontinence: Current and future perspectives

Abstract

Fecal incontinence has a profound impact in a patient’s life, impairing quality of life and carrying a substantial economic burden due to health costs. It is an underdiagnosed condition because many affected patients are reluctant to report it and also clinicians are usually not alert to it. Patient evaluation with a detailed clinical history and examination is very important to indicate the type of injury that is present. Endoanal ultrasonography is currently the gold standard for sphincter evaluation in fecal incontinence and is a simple, well-tolerated and non-expensive technique. Most studies revealed 100% sensitivity in identifying sphincter defect. It is better than endoanal magnetic resonance imaging for internal anal sphincter defects, equivalent for the diagnosis of external anal sphincter defects, but with a lower capacity for assessment of atrophy of this sphincter. The most common cause of fecal incontinence is anal sphincter injury related to obstetric trauma. Only a small percentage of women are diagnosed with sphincter tears immediately after vaginal delivery, but endoanal ultrasonography shows that one third of these women have occult sphincter defects. Furthermore, in patients submitted to primary repair of these tears, ultrasound revealed a high frequency of persistent sphincter defects after surgery. Three-dimensional endoanal ultrasonography is currently largely used and accepted for sphincter evaluation in fecal incontinence, improving diagnostic accuracy and our knowledge of physiologic and pathological sphincters alterations. Conversely, there is currently no evidence to support the use of elastography in fecal incontinence evaluation.

Keywords: Endoanal ultrasonography, Fecal incontinence, External anal sphincter, Internal anal sphincter, Obstetric anal sphincter injuries, Three-dimensional endoanal ultrasonography, Elastography

Core tip: Clinicians need to be more alert to fecal incontinence, which is a serious under-reported problem. Endoanal ultrasonography is currently the gold standard for sphincter evaluation in these patients. The most important cause of fecal incontinence is obstetric injury and the most relevant questions and controversies are related to this. The diagnosed of sphincter injury after delivery and after complete primary repair is much lower to that found by ultrasonography, and many of these women developed fecal incontinence. The clinical evaluation, technical aspects, advantages and limitations and the current role of three dimensional ultrasonography and real-time elastography will also be discussed.