Anorectal functional testing in anal incontinence

Before any specific exploration of anal incontinence (IA), a morphologicalexamination including either a complete colonoscopy, or arectosigmoidoscopy associated with a barium rectal injection, mustbe discussed among all patients presenting incontinence with anempty rectum and that according to the clinical context (family antecedentsof colonic cancer, age, clinical symptoms….).Specific explorations of the IA will aim to answer several questions:1/ Does there exist a sphincter deficiency responsible for the IA?Anorectal manometry, by determining the value of the resting analpressure as well as the amplitude and the duration of the voluntarycontraction of the external anal sphincter, makes it possible to knowif there is a deficiency of the anal sphincter. Clinical examinationcan sometimes be as powerful as anorectal manometry in answeringthis question. Nevertheless, the manometric examination also makesit possible to evaluate the rectal functional capacity, its compliance,and to know if a rectal dysfunction cannot be in question in thephysiopathology of the IA.2/ What is the origin of the sphincter deficiency?There are two possible causes to explain sphincter deficiency: ananatomical lesion and/or a neurological disorder. Anal ultrasoundmakes it possible to diagnose the presence of a lesion of the internalanal sphincter and/or external anal sphincter as well as its extent.This examination is the examination of reference since it has anexcellent sensitivity and specificity for the diagnosis of anatomicallesions of the sphincters. When one suspects a neurological lesion,the examinations most adapted to confirm this assumption are theperineal electrophysiological tests. These tests will help to distinguishcentral or peripheral neurological disorder (radiculopathy,plexique lesions or peripheral nerve lesions). It is important to seek aneurological disorder because its presence is a factor of bad prognosisfor certain cases of surgical treatment of anal incontinence(sphincter repair).3/ What is the severity of anal incontinence?There are 3 factors of severity which decrease the prognosis of thetreatment of the IA: 1/ anal hypotonia; 2/ the presence of an anatomicallesion of the internal anal sphincter; 3/ a neurological lesiondiagnosed by electrophysiological tests.The minimal assessment of an IA includes anorectal manometry, ananal ultrasound and perineal electrophysiological tests.