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W2172290329 abstract "DEFINITION Fecal incontinence is defined as either the involuntary passage or the inability to control the discharge of fecal matter through the anus. Clinically there are three subtypes (a) passive incontinence—the involuntary discharge of stool or gas without awareness; (b) urge incontinence—the discharge of fecal matter in spite of active attempts to retain bowel contents, and (c) fecal seepage—the leakage of stool following otherwise normal evacuation. The severity of incontinence can range from the unintentional elimination of flatus to the seepage of liquid fecal matter or sometimes the complete evacuation of bowel contents. Not surprisingly, these events cause considerable embarrassment, which in turn can lead to a loss of self-esteem, social isolation, and a diminished quality of life (1). EPIDEMIOLOGY Although fecal incontinence affects people of all ages, its prevalence is disproportionally higher in women, in the elderly, and in nursing home residents. Estimates of its prevalence vary greatly and depend on the clinical setting, the influence of social stigma, the definition of incontinence, and the frequency of occurrence. In the U.S. householder survey, frequent leakage of stool or fecal staining for more than 1 month was reported by 7.1% and 0.7% of the population, respectively (2). In contrast, two or more episodes of fecal incontinence per month were reported by 0.8% of patients presenting to primary care clinics in the UK (3). In an elderly (>65 yr) self-caring population, fecal incontinence occurred at least once a week in 3.7% of subjects and in more men than women (men:women = 1.5:1) (4). In contrast, 25–35% of institutionalized patients (5) and 10–25% of hospitalized geriatric patients (6) suffer from fecal incontinence. In the United States, fecal incontinence is the second leading cause for placement in nursing homes (6). In a survey of 2,570 households, comprising 6,959 individuals, the prevalence of at least one episode of incontinence during the previous year was 2.2%; among these 63% were women, 30% were >65 yr of age, 36% were incontinent of solid stool, 54% of liquid stool, and 60% of flatus (7). Furthermore, in another prospective survey of patients attending either a gastroenterology or a primary care clinic, over 18% reported fecal incontinence at least once a week (8). Only one third had ever discussed the problem with a physician (8). When stratified for the frequency of episodes, 2.7% of patients reported daily incontinence, 4.5% weekly, and 7.1% once per month (8). In another survey, fecal incontinence was associated with urinary incontinence in 26% of women attending a Uro/Gyn Clinic (9). A higher incidence of mixed fecal and urinary incontinence was also reported in nursing home residents (10, 11). The cost of health care related to fecal incontinence includes items that can be measured such as the evaluation, diagnosis and treatment of incontinence, medications, the use of disposable pads and other ancillary devices, skin care, and nursing care. Approximately $400 million/year were spent for adult diapers (8, 12) and between $1.5 and $7 billion/year were spent on care for incontinence among institutionalized elderly patients (6, 13). In a long-term facility, the annual cost for a patient with both mixed fecal and urinary incontinence was $9,711 (14). In the outpatient setting, the average cost per patient (including evaluation) was estimated at $17,166 (15). Additionally, there are other costs that cannot be measured such as the impaired quality of life and social dysfunction (1). SUMMARY. The prevalence of fecal incontinence ranges between 1% and 7.4% in otherwise healthy people and up to 25% in those who are institutionalized. Both the embarrassment and the social stigma attached to this disorder, often delay presentation as well as treatment for several years. Fecal incontinence not only causes significant morbidity in the community but it also consumes substantial health care resources. PATHOPHYSIOLOGY Functional Anatomy and Physiology of the Anorectum The neuromuscular integrity of the rectum, anus, and the adjoining pelvic floor musculature helps to maintain normal fecal continence. The rectum is a muscular tube composed of a continuous layer of longitudinal muscle that interlaces with the underlying circular muscle. This unique muscle arrangement enables the rectum to serve both as a reservoir for stool and as a pump for emptying stool. The anus is a muscular tube 2–4 cm. long, which at rest forms an angle with the axis of the rectum. At rest, the anorectal angle is approximately 90 degrees, with voluntary squeeze it becomes more acute, approximately 70 degrees, and during defecation it becomes more obtuse, about 110–130 degrees. The anal sphincter consists of the internal anal sphincter, which is a 0.3–0.5 cm thick expansion of the circular smooth muscle layer of the rectum, and the external anal sphincter which is a 0.6–1 cm thick expansion of the striated levator ani muscles. Morphologically, both sphincters are separate and heterogeneous (16). The anus is normally closed by the tonic activity of the internal anal sphincter and this barrier is reinforced by the external anal sphincter during voluntary squeeze. The anal mucosal folds together with the expansile anal vascular cushions provide a tight seal. These mechanical barriers are augmented by the puborectalis muscle, which forms a flap-like valve that creates a forward pull and reinforces the anorectal angle to prevent incontinence (16). The anorectum is innervated by sensory, motor, and autonomic parasympathetic nerves as well as by the enteric nervous system. The principal nerve is the pudendal nerve, which arises from the second, third, and fourth sacral nerves and innervates the external anal sphincter, the anal mucosa, and the anorectal wall. This is a mixed nerve and subserves both sensory and motor function (17). Its course through the pelvic floor makes it vulnerable to stretch injury, particularly during vaginal delivery. It is likely that rectal contents are periodically sensed by the process of “ano rectal sampling” (18, 19). This process may be facilitated by transient relaxations of the internal anal sphincter that allows the movement of stool or flatus from the rectum into the upper anal canal where they may come into contact with specialized sensory end organs such as the numerous Krause end-bulbs, Golgi–Mazzoni bodies and genital corpuscles and the relatively sparse Meissner's corpuscles and Pacinian corpuscles (20). Specialized afferent nerves for touch, cold, tension, and friction subserve these organized nerve endings. An intact “sampling reflex” allows the individual to choose whether to discharge or retain their rectal contents, whereas an impaired “sampling reflex” may predispose to incontinence (19, 20). In contrast, the rectal epithilium shows no organized nerve endings (21). Myelinated and unmyelinated nerve fibers are present adjacent to the rectal mucosa, the submucosa and the myenteric plexus. These subserve the sensation of distention and stretch and mediate the viscero-visceral, the rectoanal inhibitory, and contractile responses (22). The sensation of rectal distention travels along the parasympathetic system to S2, S3, and S4 (21). Thus, the sacral nerves are intimately involved with the sensory, motor, and autonomic function of the anorectum and in maintaining continence. Pathogenic Mechanisms and Etiology Incontinence occurs when one or more mechanisms that maintain continence are disrupted to an extent that other mechanisms are unable to compensate. Thus, the cause of fecal incontinence is often multifactorial (23–25). In a prospective study, 80% of patients had more than one pathogenic abnormality (23). In adult women, obstetric trauma is a major predisposing factor (26). This injury may involve either the external anal sphincter, the internal anal sphincter, or the pudendal nerves or all three structures. In prospective studies, nearly 35% of primiparous women (normal ante partum) showed evidence of sphincter disruption following vaginal delivery (26–28). Other important risk factors include forceps delivery, prolonged second stage of labor, large birth weight, and occipito-posterior presentation (29–31). Perineal tears, even when carefully repaired, can be associated with incontinence, and patients may either present immediately or several years following delivery (27). Other causes of anatomic disruption include iatrogenic factors such as anorectal surgery for hemorrhoids, fistulas, or fissures. Anal dilatation or lateral sphincterotomy may result in permanent incontinence due to fragmentation of the internal anal sphincter (32, 33). The internal anal sphincter is occasionally and inadvertently damaged during hemorrhoidectomy (34). Accidental perineal trauma or a pelvic fracture may also cause direct sphincter trauma leading to incontinence (35). In the absence of structural defects, internal anal sphincter dysfunction may occur because of a myopathy (36, 37), or internal sphincter degeneration (37), or a complication of radiotherapy (38, 39). Neurological diseases can affect continence by interfering with either sensory perception or motor function, or both. In the central nervous system, multiple sclerosis, dementia, stroke, brain tumors, sedation, dorsal and spinal cord lesion may each cause incontinence (40–43). In the peripheral nervous system, cauda equina lesions, diabetic neuropathy (41, 44, 45), toxic neuropathy from alcohol, or traumatic neuropathy in the post partum setting may all lead to fecal incontinence. Up to 30% of patients with multiple sclerosis are incontinent (41). Skeletal muscle disorders such as muscular dystrophy, myasthenia gravis, and other myopathies can affect external anal sphincter and puborectalis function. Reconstructive procedures such as ileoanal (46) or coloanal pouches (47) can increase anorectal capacity and may improve continence. However, up to 40% of patients with an ileoanal pouch experience periodic, often nocturnal fecal incontinence, possibly related to uncoordinated pouch contractions (48). Similarly, rectal prolapse may be associated with fecal incontinence in up to 88% of cases (49–51). This is most likely due to prolonged inhibition of anal tone from intussusception of the rectum into the upper anal canal. Conditions that decrease rectal compliance and accommodation may also cause fecal incontinence (52). Etiologies include radiation-induced inflammation and fibrosis, rectal inflammation secondary to ulcerative colitis (53, 54), or Crohn's disease and infiltration of the rectum by tumor, ischemia, or following radical hysterectomy (39). Rarely other causes include high intrarectal pressures generated in some patients with ulcerative colitis (53), or with severe voluminous diarrhea (55). In many patients fecal seepage or staining of undergarments is due to the incomplete evacuation of stool. A majority of these patients show obstructive or dyssynergic defecation (56). In these patients, anal sphincter and pudendal nerve function are intact but the ability to evacuate stool is impaired (56). Many also exhibit impaired rectal sensation (56, 57). Similarly, in the elderly and in children with functional incontinence, the prolonged retention of stool in the rectum leads to fecal impaction. Fecal impaction causes prolonged relaxation of the internal anal sphincter tone that allows liquid stool to flow around impacted stool and to escape through the anal canal (58). SUMMARY. Anal sphincter disruption or weakness, pudendal neuropathy, impaired anorectal sensation, impaired rectal accommodation, or incomplete evacuation may all contribute to the pathogenesis of fecal incontinence. These changes may be a consequence of local, anatomical, or systemic disorders. Thus, the origin of fecal incontinence is often multifactorial. CLINICAL ASSESSMENT OF FECAL INCONTINENCE Recommendation: Patients with fecal incontinence may be categorized into passive or urge incontinence or fecal seepage and their severity can be graded based on a prospective stool diary and clinical features. The evaluation of a patient with fecal incontinence involves a detailed clinical assessment together with the appropriate physiological and imaging tests of the anorectum. These three sources of information are complementary and should provide useful data regarding the severity of the problem, the underlying etiological factors, and the impact of the problem on the quality of life. Equipped with this knowledge, it is possible to design appropriate treatment strategies that could lead to clinical improvement. Clinical Features Many patients who suffer with fecal incontinence or soiling, take refuge under the term “diarrhea” or “urgency” (59). Thus, the first step in the evaluation is to establish a rapport with the patient and to confirm the existence of fecal incontinence. Thereafter, further characterization is desirable. This can include an assessment of its duration, its progression, its nature, i.e., incontinence of flatus, liquid stool, or solid stool, and its impact on the quality of life (Table 1). The use of pads or other devices and the ability to discriminate between formed or unformed stool and gas should be enquired. A detailed inquiry should also include obstetric history, a history of coexisting conditions such as diabetes mellitus, pelvic radiation, neurological problems or spinal cord injury, dietary history, and a history of coexisting urinary incontinence. Also, during clinical assessment, it is useful to ask if a patient can differentiate between formed and unformed stool or flatus, i.e., the presence of rectoanal agnosia. A prospective stool diary may also be very useful (Fig. 1).Table 1: A List of Important Information That Should be Elicited When Taking a History in a Patient with Suspected Fecal IncontinenceFigure 1: A sample stool diary for assessing patients with fecal incontinence. Use the following descriptors for describing stool consistency: Type 1: Separate hard lumps. Type 2: Sausage shaped but lumpy. Type 3: Like a sausage but with cracks on its surface. Type 4: Like a sausage or snake, smooth and soft. Type 5: Soft blobs with clear-cut edges (passed easily). Type 6: Fluffy pieces with ragged edges, a mushy stool. Type 7: Watery.The circumstances under which incontinence occurs should also be determined. Such a detailed inquiry may facilitate the identification of the following possible scenarios: Passive incontinence—which is the involuntary discharge of fecal matter or flatus without any awareness. This suggests a loss of perception and/or impaired rectoanal reflexes either with or without sphincter dysfunction. Urge incontinence—which is the discharge of fecal matter or flatus in spite of active attempts to retain these contents. Here, there is a predominant disruption of the sphincter function or the rectal capacity to retain stool. Fecal seepage—which is the undesired leakage of stool, often after a bowel movement with otherwise normal continence and evacuation. This condition is mostly due to incomplete evacuation of stool and/or impaired rectal sensation (56, 58). The sphincter function and pudendal nerve function are mostly intact (56, 57). Although there is an overlap between these three groups, by making a clinical distinction, it is possible to assess the underlying etiology and to guide investigations and management. Symptom assessment can also provide useful insights regarding the underlying mechanism(s), but may not correlate well with manometric findings. In one study, leakage had a sensitivity of 98.9%, a specificity of 11%, and a positive predictive value of 51% for detecting low resting anal sphincter pressures (31). The positive predictive value for detecting a low squeeze pressure was 80% (31). Thus, for an individual patient with incontinence, history and clinical features alone are insufficient to define the pathophysiology and therefore objective testing is essential. Nevertheless, based on the clinical features, several grading systems have been proposed. Recently, a modification of the Cleveland Clinic grading system (60) has been validated by the St. Mark's investigators (61). This system can provide an objective method of quantifying the degree of incontinence. It can also be useful for assessing the efficacy of therapy. This grading system is based on seven parameters that include whether the anal discharge is either solid, liquid or flatus, and whether the problem causes alterations in lifestyle, (scores: Never = 0, Always = 5); the need to wear a pad or the need to take antidiarrheal medication, and the ability to defer defecation (scores: No—0, yes—2). The score ranges from 0 (continent) to 24 (severe incontinence). Clinical features alone are, however, insufficient to define the pathophysiology. The use of validated questionnaires such as the SCL-90R SF-36 may provide additional information regarding the psychosocial issues and impact on the quality of or life. Physical Examination This should include a detailed physical and neurological examination of the back and the lower limbs, because incontinence may be secondary to a systemic or a neurological disorder. The perineal inspection and digital rectal examination is best performed with the patient lying in the left lateral position and with good illumination. Upon inspection, the presence of fecal matter, prolapsed hemorrhoids, dermatitis, scars, skin excoriation, the absence of perianal creases, or a gaping anus may be noted. These features suggest either sphincter weakness or chronic skin irritation and provide clues regarding the underlying etiology. Excessive perineal descent or rectal prolapse can be demonstrated by asking the patient to attempt defecation. An outward bulge that exceeds 3 cm is usually defined as excessive perineal descent (62). The perianal sensation should also be checked. The anocutaneous reflex examines the integrity of the connection between the sensory nerves and the skin, the intermediate neurons in the spinal cord segments S2, S3, and S4, and the motor innervation of the external anal sphincter. This can be assessed by gently stroking the perianal skin with a cotton bud in each of the perianal quadrants. The normal response consists of a brisk contraction of the external anal sphincter. Impaired or absent anocutaneous reflex suggests either afferent or efferent neuronal injury (63). Digital Rectal Examination Recommendation: Digital rectal examination can identify patients with fecal impaction and overflow. It is not accurate enough for diagnosing sphincter dysfunction or for initiating therapy. After inserting a lubricated, gloved index finger, one should assess the resting sphincter tone, the length of the anal canal, the integrity of the puborectalis sling, the acuteness of the anorectal angle, the strength of the anal muscle, and the elevation of the perineum during voluntary squeeze. Also, the presence of a rectocele or impacted stools may be noted. Unlike the examination of other organs, one should exercise considerable sensitivity and allay any fears when performing a digital rectal examination. The accuracy of digital rectal examination—as an objective test for evaluating anal sphincter function—has been assessed in several studies. In one study of 66 patients, digital examination by an experienced surgeon was somewhat correlated with resting sphincter pressure (r = 0.56; p < 0.001) or maximum squeeze pressure (r = 0.72: p < 0.001) (64). In another study of 280 patients with several anorectal disorders, a reasonable correlation was reported between digital palpation and manometry (65). However, the sensitivity, the specificity, and the positive predictive value of the digital exam were very low (65). By the digital exam, the positive predictive value of detecting a low sphincter tone was 66.7% and a low squeeze tone was 81% (31). In another study of 64 patients, the agreement between digital examination and resting anal canal pressure or squeeze pressure was 0.41 and 0.52, respectively (66). These data suggest that digital examination is only an approximation, which is influenced by many factors including the size of the examiner's finger, the technique, and the cooperation of the patient. Thus, it is not very reliable and is prone to interobserver differences.Table 2: Treatment of Fecal IncontinenceINVESTIGATIONS OF FECAL INCONTINENCE Recommendation: Endoscopic evaluation of the rectosigmoid region is appropriate for detecting mucosal disease or neoplasia that may contribute to fecal incontinence. At the outset it is important to distinguish whether the incontinence is either secondary to diarrhea or independent of stool consistency. If there is coexisting diarrhea, a flexible sigmoidoscopy or colonoscopy should be performed to exclude colonic mucosal inflammation, a rectal mass, or stricture. Stool studies, including stool screening for infection, stool volume, stool osmolality and electrolytes may be performed. Similarly, biochemical tests may reveal thyroid dysfunction, diabetes and other metabolic disorders. Breath tests may reveal lactose or fructose intolerance or bacterial overgrowth (24). Several specific tests are available for defining the underlying mechanisms of fecal incontinence (23, 52, 63, 67). These tests are often complementary (23, 52, 63, 67). The most useful tests are anorectal manometry, anal endosonography, balloon expulsion test and pudendal nerve terminal motor latency (23, 52, 63, 67). A description of these tests and others that are commonly used for the evaluation of fecal incontinence and their clinical significance has been discussed in detail by Diamant et al. (67). Hence, a brief description of these tests and their clinical relevance is presented here with particular emphasis on recent literature and contentious issues. Anorectal Manometry and Sensory Testing Recommendation: Anorectal manometry with rectal sensory testing is the preferred method for defining the functional weakness of the external or internal anal sphincter and for detecting abnormal rectal sensation. Measurement of rectal compliance (reservoir function) may be helpful in some patients. These tests may also facilitate biofeedback training. Anorectal manometry provides an objective assessment of anal sphincter pressures together with an assessment of rectal sensation, rectoanal reflexes, and rectal compliance. Currently, several types of probes and pressure-recording devices are available. Each system has distinct advantages and drawbacks (63, 68, 69). A water-perfused probe with multiple closely spaced sensors is commonly used (63, 69). Alternatively, a solid-state probe with micro-transducers may be used (63, 69). Although more expensive and fragile, they do not require perfusion equipment, are easier to calibrate, and are possibly more accurate (63, 68). The anal sphincter pressures can be measured by stationary, station pull-through, or rapid pull-through techniques, but the former two are probably more accurate (63, 67, 68). A rapid pull-through technique can give falsely high sphincter pressures (67, 70). The resting anal sphincter pressure predominantly represents the internal anal sphincter function and the voluntary squeeze anal pressure predominantly measures the external anal sphincter function. Patients with incontinence have been shown to have low resting and low squeeze sphincter pressures (65, 71, 72). The duration of the sustained squeeze pressure provides an index of sphincter muscle fatigue. The ability of the external anal sphincter to contract in a reflex manner can also be assessed during abrupt increases of intraabdominal pressure such as when coughing (25, 63, 68, 69). This reflex response causes the anal sphincter pressure to rise above that of the rectal pressure to preserve continence. The response may be triggered by receptors on the pelvic floor and mediated through a spinal reflex arc. In patients with spinal cord lesions above the conus medullaris, this reflex response is present but the voluntary squeeze may be absent, whereas in patients with lesions of the cauda equina or sacral plexus both the reflex response and the voluntary squeeze response are absent (63, 73, 75). The response may be triggered by receptors on the pelvic floor and mediated through a spinal reflex arc. Sensory Testing Rectal balloon distention with either air or water can be used for the assessment of both the sensory responses and the compliance of the rectal wall. By distending a balloon in the rectum with incremental volumes, it is possible to assess the thresholds for first perception, a first desire or an urgent desire to defecate (25, 52, 63, 68, 69). A higher threshold for sensory perception suggests impaired rectal sensation (23, 25, 41, 52, 71). Also, the balloon volume required for partial or complete inhibition of anal sphincter tone can be assessed. It has been shown that the volume required to induce reflex anal relaxation was lower in incontinent patients than controls (71, 74). Because sampling of rectal contents by the anal mucosa may play an important role in maintaining continence (18, 19), quantitative assessment of anal perception using either electrical (22) or thermal (22, 76) stimulation has been advocated. In one study, anal mucosal sensation was assessed by recording perception threshold for electrical stimulation of the mid anal canal using a ring electrode (77). A combined sensory and motor defect was seen in patients with incontinence (77). In another study, although anal canal perception was impaired immediately after a vaginal delivery, there was no difference at 6 months (78). The role of thermosensitivity appears controversial (22). In one study, the ability of healthy anal mucosa to differentiate between small changes in temperature has been questioned (79). Hence, under normal conditions it is not possible to appreciate the temperature of fecal matter passing from the rectum to the anal canal during sampling (79). Whether patients have a pure sensory defect of anus without coexisting sphincter dysfunction or rectal sensory impairment has not been shown. In contrast, a combined sensory and motor defect has been reported in many studies (77, 78, 80). Rectal compliance can be calculated by assessing the changes in rectal pressure during balloon distention with air or fluid (41, 44, 52, 67, 68). The ratio dv/dp describes the relationship. Rectal compliance is reduced in patients with colitis (53, 54) and in patients with low spinal cord lesions and in diabetics with incontinence (41, 44, 52). In contrast, compliance is increased in high spinal cord lesion (42, 75). When performed meticulously, anorectal manometry can provide useful information regarding anorectal function (23, 52, 67, 80). A technical review recommended the use of anorectal manometry for the evaluation of patients with incontinence because it can define the functional weakness of one or both sphincters and helps to perform and evaluate the responses to biofeedback training (67). Unfortunately, to date there has been no uniform technique or equipment for performing anorectal manometry (81). Also, there is a dearth of normative data and uniform methods of interpreting test results. Hence, there is an urgent need to develop standards of testing anorectal function and to validate the significance of abnormal results. Recently, the American Motility Society has initiated an international collaborative effort to develop standards for manometry testing and a consensus document has been published (82). Such efforts may lead to standardization of testing and interpretation of anorectal manometry. Although there are insufficient data regarding normal values, overlap among healthy subjects and patients with incontinence (65, 67), and large confidence intervals in studies that have examined test reproducibility (64, 83), for the individual patient with incontinence, manometry testing can be very useful. Manometric tests of anorectal function may also be useful in assessing objective improvement following drug therapy (84), biofeedback therapy (85), or surgery (86). Imaging the Anal Canal Recommendation: Anal endosonography is the simplest, most widely available and least expensive test for defining structural defects of the anal sphincter and should be considered in patients with suspected fecal incontinence. ANAL ENDOSONOGRAPHY. Traditionally, anal endosonography has been performed using a 7 mHz rotating transducer with a focal length of 1–4 cm (87). It provides an assessment of the thickness and structural integrity of the external and internal anal sphincter muscle and can detect the presence of scarring, loss of muscle tissue, and other local pathology (87, 88). More recently, higher frequency (10–15 mHz) probes that provide better delineation of the sphincter complex have become available (89). After vaginal delivery, anal endosonography has revealed occult sphincter injury in 35% of primipara women and most of these lesions were not detected clinically (27). In another study, sphincter defects were detected in 85% of women with third-degree perineal tear compared with 33% of subjects without tears (28). In studies that compared EMG mapping with anal endosonography, there was a high concordance rate for identifying sphincter defects using both modalities (90, 91). The technique is, however, operator dependent and requires both training and experience (67). Although endosonography can distinguish an internal sphincter injury from that of an external sphincter injury, it has a low specificity for demonstrating the etiology of fecal incontinence (92). Because anal endosonography is more widely available, is less expensive, and is certainly less painful than needle insertion, currently, it is the preferred technique for examining the" @default.
W2172290329 created "2016-06-24" @default.
W2172290329 creator A5017818369 @default.
W2172290329 date "2004-08-01" @default.
W2172290329 modified "2023-10-07" @default.
W2172290329 title "Diagnosis and Management of Fecal Incontinence" @default.
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