A theory of progression from obstructed defecation to fecal incontinence.

Abstract

Fecal disorders have a relevant social impact because they impair the quality of life of the patient and add to the cost of healthcare. In order to shed light on the pathophysiology of fecal disorders it is helpful to consider the progression of obstructed defecation to fecal incontinence which occurs in women without anal sphincter defects who have descending perineum syndrome. The overall prevalence of chronic constipation in the general population is about 15 %, and the most common subtype among women is obstructed defecation. Obstructed defecation occurs in 47.7 % of Italian patients affected by chronic constipation. Dyssynergia alone is present in young women (median age 38 ± 14 years), whereas dyssynergia plus structural diseases, such as rectocele, rectal intussusception, mucosal prolapse and perineal descent materialize in middle-aged women (median age 52 ± 14 years) [1]. Therefore there is no doubt that ageing is implicated in the evolution from functional to anatomic pelvic floor disorders. In parallel, excessive abdominal straining at stool evacuation causes progressive perineal descent: the recurrent straining against defecatory outlet obstruction impairs pelvic floor muscle tone until it disappears completely. In this way descending perineum overlaps with pelvic floor dyssynergia [2]. Older age is correlated with both dynamic and fixed descending perineum [3], and excessive perineal descent is found in 78 % of elderly patients with evacuation disorders [4]. The organic descent of the hypotonic pelvic floor combined with pudendal neuropathy explains the appearance of fecal incontinence. Perineal descent involves the anterior, middle and posterior pelviperineal areas in women. Uro-gynecological structures and proctologic segments are all implicated and thus pelvic organ prolapse may coexist with rectoanal intussusception, rectal prolapse and rectocele [5]. Fecal incontinence is a physically and psychologically disabling condition which has a negative impact on the quality of life of the patient. The prevalence of fecal incontinence in community-dwelling women in the USA varies considerably depending on the population studied, ranging from 2.2 to 17 % of women housed in communities and up to almost half of all nursing home residents. Fecal incontinence is often related to several specific diseases, such as diabetes mellitus, dementia, irritable bowel syndrome, cerebrovascular disease, pelvic-anal surgery, traumatic sphincter lesions and post-partum incontinence. Even when excluding the presence of these cases, women over 65 years often have combined chronic constipation and fecal incontinence (32.7 % of constipated women) and women with anal incontinence have greater values of descending perineum measures than those without anal incontinence [6]. Therefore, these last epidemiological data support the hypothesis of a link between obstructed and fecal incontinence via descending perineum syndrome. Obstructed defecation can be caused by organic or functional diseases which are difficult to untangle. Mechanical causes include rectocele, rectoanal intussusception, descending perineum syndrome, solitary rectal ulcer syndrome, mucosal rectal prolapse, enterocele and sigmoidocele. Disorders of rectal sensation and pelvic floor dyssynergia are the functional diseases. Patients with rectal hyposensitivity have most commonly constipation (48 %), combined constipation and incontinence (27 %), or fecal incontinence (20 %). Obstructed defecation patients have a & F. Pucciani pucciani@unifi.it