Functional Anorectal Disorders

Abstract

This report defines criteria and reviews the epidemiology, pathophysiology, and management of common anorectal disorders: fecal incontinence (FI), functional anorectal pain and functional defecation disorders. FI is defined as the recurrent uncontrolled passage of fecal material for at least 3 months. The clinical features of FI are useful for guiding diagnostic testing and therapy. Anorectal manometry and imaging are useful for evaluating anal and pelvic floor structure and function. Education, antidiarrheals and biofeedback therapy are the mainstay of management; surgery may be useful in refractory cases. Functional anorectal pain syndromes are defined by clinical features and categorized into three subtypes. In proctalgia fugax, the pain is typically fleeting and lasts for seconds to minutes. In levator ani syndrome (LAS) and unspecified anorectal pain the pain lasts more than 30 minutes, but in LAS there is puborectalis tenderness. Functional defecation disorders are defined by >2 symptoms of chronic constipation or irritable bowel syndrome with constipation, and with >2 features of impaired evacuation i.e., abnormal evacuation pattern on manometry, abnormal balloon expulsion test or impaired rectal evacuation by imaging. It includes two subtypes; dyssynergic defecation and inadequate defecatory propulsion. Pelvic floor biofeedback therapy is effective for treating LAS and defecatory disorders.

Keywords: Anorectal disorders; Anorectal pain; Biofeedback therapy; Constipation; Dyssynergic defecation; Fecal incontinence; Levator ani syndrome.

Figure 1

Anatomy of the anal canal and rectum, which displays the key physiologic mechanisms for continence and defecation.

Figure 2

Effect of biofeedback therapy on dyssynergia in 1 patient before and after treatment. Panel A shows baseline intrarectal and anal sphincter pressures. There is inadequate propulsion and paradoxical anal contraction. Panel B shows that after learning diaphragmatic breathing technique, the pushing effort has improved but patient still shows paradoxical contraction. Panel C shows coordinated relaxation, with an increase in intrarectal pressure and relaxation of the anal sphincter. Adapted from Rao, with permission.