Surgical management of anal incontinence

The complex nature of the continence mechanism is reflected in the difficulties experienced in the surgical management of patients with faecal incontinence. Apparent anatomical abnormalities may be identified but the functional outcome following surgery may be unsatisfactory. It is therefore important to improve both the selection of patients as well as the surgical procedures themselves. Selection of patients for appropriate treatment should be based on clinical findings as well as anorectal physiology tests. Most patients referred for assessment fall into one of six categories: incontinence with a normal sphincter; minor incontinence due to local anal conditions; direct sphincter injury; neurogenic ("idiopathic") incontinence; rectal prolapse; generalised neurological condition. Minor anal conditions causing incontinence must be carefully identified for appropriate treatment. A large amount of work has been done over the past ten years on the pathophysiology of major incontinence and new surgical procedures have been developed. A common difficulty is deciding whether anterior sphincter attenuation or neurogenic weakness is the dominant lesion causing incontinence; overlapping sphincter repair is indicated for the former and postanal repair for the latter. Anorectal physiology studies can be helpful in differentiating these conditions and are now used routinely in the assessment of patients.