Epidemiology
Fecal incontinence, the involuntary leakage of liquid or solid stool, and anal incontinence, including the involuntary leakage of gas, are devastating problems. Many people find these conditions socially incapacitating and stay home, minimizing social contact to avoid embarrassing situations. Estimates of the number of people afflicted with fecal incontinence likely underrepresent the prevalence, because many do not mention the problem to their caregivers, and health care providers do not routinely screen for these symptoms ( ). Definitions of fecal incontinence also vary from report to report, making comparisons difficult. A 2013 review performed as part of a National Institutes of Health State of the Science Workshop reported that fecal incontinence occurred in 7% to 15% of community-dwelling people ( ). In a large systematic review, the median prevalence of fecal incontinence in women in the community was 8.9% (range 2.0%–20.7%), and the median prevalence of anal incontinence was 15.9% (range 2.2%–47.0%) ( ).
The economic burden of fecal incontinence is high, including direct medical and surgical costs, as well as costs for pads, diapers, and other personal hygiene products. Fecal incontinence is one of the most common reasons for nursing home placement. Fecal incontinence increases progressively with age, although it can affect all ages. Although obstetric trauma is a known risk factor for fecal incontinence in women, fecal incontinence impacts both genders with similar prevalence rates. Other risk factors for fecal incontinence include diarrhea, chronic illness, smoking, and obesity. More information about the epidemiology and significant psychosocial impact of fecal incontinence can be found in Chapter 6 .
Etiology
Defecation is a complex process that involves the interaction between anal function and sensation, rectal compliance, stool consistency, stool volume, colonic transit, and cognitive control. An alteration in any of these can lead to incontinence. Box 27.1 lists some common causes of fecal incontinence.
Anal
Injury
Obstetric (vaginal delivery/trauma)
Surgical (fistulotomy, hemorrhoidectomy, sphincterotomy, stretch)
Irradiation
Trauma
Congenital (e.g., imperforate anus)
Intestinal
Colitis or proctitis
Colon, rectum, or small bowel resection
Tumors
Fecal impaction
Decreased rectal compliance
Rectal prolapse
Neurologic
Central nervous system
Dementia
Neoplasm
Stroke
Trauma
Multiple sclerosis
Peripheral (e.g., diabetes)
Other
Diarrhea
Combinations of anal and rectal causes
Myopathy (e.g., scleroderma)
Functional
Obesity
A large component of continence is the function of the anal sphincter complex, consisting of the internal anal sphincter muscle, the external anal sphincter muscle, and the puborectalis muscle ( Fig. 27.1 ). The smooth muscle of the internal sphincter is innervated by the autonomic nervous system, whereas the external sphincter striated muscle is innervated by the inferior rectal branch of the pudendal nerve. Traditionally, the internal anal sphincter has been thought to be largely responsible for sphincter resting tone, with a smaller contribution by the external sphincter muscle. However, others suggest that the external sphincter may play a greater role in baseline sphincter pressure ( ). The external anal sphincter is voluntarily recruited during rectal filling, aiding with increased sphincter pressure and maintenance of continence. Defecation is a result of voluntary relaxation of the external sphincter and puborectalis muscles, innervated by the S3–S4 nerves, in response to rectal distension that is dictated by receptors in the pelvic floor and the anal transition zone. Chapter 4 includes a detailed description of the anatomy, innervation, and function of the anorectum.
Anatomic disruption of the sphincter complex and dysfunction because of neurologic reasons are frequent causes of fecal incontinence. Vaginal birth, and particularly forceps-assisted operative vaginal delivery, commonly injures the mother’s sphincter complex. In seminal research, studied women before and after childbirth, with interviews, anal physiology testing, and anal endosonography, and found that 35% of primiparous women and 44% of multiparous women had sphincter defects as seen on endoanal ultrasound after delivery. The internal anal sphincter was injured more often than the external sphincter—sometimes even when no breach occurred in the perineal skin. A strong correlation was found between sphincter defects and the development of bowel symptoms, although only about a third of women with sphincter defects developed bowel symptoms. Studies have reported worsening fecal continence status in women with prior anal sphincter injury and subsequent vaginal delivery, particularly those with an anal sphincter defect seen on ultrasound after first delivery ( ). However, subsequent vaginal delivery appears safe in some women with prior sphincter injury. Vaginal delivery was not associated with significant worsening of anorectal symptoms or function in 99 women with prior obstetric anal sphincter injury who did not have significant fecal incontinence symptoms or anal sphincter defect on ultrasound after the birth injury ( ).
This and other research have demonstrated a clear association between obstetric injury and early-onset fecal incontinence. In some women, fecal incontinence symptoms may develop decades after an obstetric injury, possibly because other mechanisms maintain continence during that interval. The long-term risk of incontinence in women with a prior sphincter injury is still unclear. An epidemiological study including over 7000 Swedish women 40 to 60 years of age demonstrated that the risk of new fecal incontinence increased after age 52 years to a significantly greater extent in women with a history of obstetric anal sphincter injury compared with women without a sphincter injury, suggesting that a persistent risk extends at least into early menopause ( ). However, similar to urinary incontinence, obstetric injury appears to be a less important risk factor for fecal incontinence that occurs in elderly women, when other contributing factors are common (see Box 27.1 ).
Evaluation
History
A comprehensive history is critical to the evaluation of a patient with fecal incontinence, focusing on bowel habits and incontinence symptoms (see also Chapter 9 ). Important questions to ask include duration of the problem, frequency of incontinence, time of day of incontinence, type of stool lost, ability to control flatus, use of pads, frequency of bowel movements, typical stool consistency, and effects of incontinence on daily life. The presence of fecal urgency is important. Urgency may reflect inability of the rectal reservoir to store stool (as with diarrhea or proctitis) rather than a sphincter problem. The consistency of incontinent stool may be related to the severity of the incontinence. Flatus is more difficult to control than liquid stool, and solid stool is the most easily controlled. Patients with incontinence of solid stool without knowledge of the loss of stool may be more distressed than those with incontinence of flatus only.
The obstetric history may also be relevant, including number of vaginal deliveries, use of vacuum or forceps, episiotomy, perineal tears or infections, and neonatal weight. A sexual history, including the practice of anal intercourse and the effect of incontinence on sexual behavior, should be obtained. Other medical and surgical conditions must be ascertained, particularly gastrointestinal and neurological disorders, as well as back injuries, previous anorectal or abdominal surgeries, irradiation history, and diabetes. Medications, food intolerance, and activity restrictions may add information.
The Bristol Stool Form Scale and bowel diaries may be used to complement the history ( ). The well-validated Bristol Stool Form Scale provides descriptions of stool consistency ranging from 1 (separate hard lumps of stool) to 7 (watery diarrhea), which can aid patients in characterizing stool consistency. This is often used with a bowel diary to provide an objective record of stool frequency, consistency, and incontinence episodes.
Physical examination
Physical examination should include abdominal, pelvic, and rectal examinations. Abdominal evaluation may help identify stool burden or other masses. Pelvic examination is used to assess for pelvic organ prolapse, including rectocele, and fistula.
The anorectal physical examination starts with inspection of the anal area, looking for soilage of stool on the skin and evidence of skin irritation. The anus is inspected, looking for gaping of the muscles and any scarring. A “dovetail” sign, where the anterior perianal folds are absent, and a shortened or thin perineal body are suggestive of an external anal sphincter defect. The patient is asked to squeeze and to simulate holding in a bowel movement to look for uniform circular contraction of muscle. Patients with a weak sphincter may contract the gluteal muscles instead of the anal sphincter. Next, asking the patient to strain may show exaggerated perineal descent or prolapse of hemorrhoids or even the rectum. The anocutaneous reflex can be checked by rubbing the perianal skin gently (a Q-tip works well) and looking for the reflex contraction of the anal sphincter mechanism, also referred to as “anal wink.” Sensation to pinprick can also be assessed. Both of these give a crude assessment of sphincter innervation.
Palpation of the sphincter is next done with digital examination. The initial tone should be noted, as it reflects the internal sphincter. Then the patient is asked to squeeze on the index finger in the anus as if she were holding in a bowel movement. Strength, defects in the circle of muscle, and early fatigability are assessed. Scars or masses are appreciated. The digital rectal examination is also used to evaluate for rectal or anal masses, occult or gross blood, fistula, and the presence of a rectocele. Anoscopy and proctoscopy may be added to the examination to help diagnose anal lesions (such as hemorrhoids or neoplasms) or proctitis (also see Colonoscopy section later).
Questionnaires for fecal incontinence
The use of validated questionnaires may be helpful clinically to assess fecal incontinence severity and functional impact (quality of life) before and after treatment. One commonly used severity scale for fecal incontinence is the American Society of Colon and Rectum Fecal Incontinence Severity Index (FISI). The FISI consists of questions that rate continence to gas, mucus, solid, and liquid stool. Other popular tools also rate lifestyle alterations and wearing of a pad, in addition to incontinence to solid and liquid stool and gas, including the Wexner Score and St. Marks (Vaizey) Score. Recently, developed and validated a new measure, the Accidental Bowel Leakage Evaluation questionnaire, based on a more comprehensive conceptual framework that includes patient-important domains of predictability, awareness, control, emptying, and discomfort. Initial reliability and validity testing in a care-seeking population of women with fecal incontinence is promising.
A validated questionnaire for measuring quality of life, the Fecal Incontinence Quality of Life (FIQL), was reported in 2000 by Rockwood et al. and has 29 items that relate to four scales: lifestyle, coping/behavior, depression/self-perception, and embarrassment. The FIQL is currently used routinely to assess quality of life during the patient’s follow-up after any mode of treatment.
Treatment success is frequently defined as at least 50% reduction in fecal incontinence episodes, although patients would prefer this number to be greater than 75%. See Chapter 41 for further discussion of these and other patient-reported outcome measures.
Diagnostic testing
Diagnostic testing for fecal incontinence may include the use of colonoscopy, endoanal ultrasound, magnetic resonance imaging (MRI), anorectal physiologic testing, and defecography. Additional testing is not required to begin treatment of fecal incontinence but is most often used if patients do not respond to conservative treatments and in more complex cases. (See Chapter 9 for further discussion.)
Colonoscopy.
Colonoscopy is indicated with new-onset fecal incontinence, mainly in the context of new onset of diarrhea and loose stool, to evaluate for cancer and inflammation seen with inflammatory bowel disease and microscopic colitis. Additionally, red flags identified during evaluation, such as weight loss, anemia, and family history of colorectal cancer or inflammatory bowel disease, will also warrant a colonoscopy. In other patients, providers should ensure that colorectal cancer screening is up to date. American Cancer Society guidelines now recommend colorectal cancer screening, which may include colonoscopy, in adults with average risk of colorectal cancer beginning at age 45 years ( ).
Endoanal ultrasonography.
Endoanal ultrasonography is a valuable tool in the assessment of fecal incontinence, particularly in patients with a history of birth trauma or anorectal surgery or when examination suggests a sphincter defect is present. A probe inserted into the rectum and withdrawn through the anal canal allows for a 360-degree visualization of the internal and external anal sphincter muscles. Imaging of the anal sphincter is most useful when anal sphincter injury is suspected and when planning anal sphincter repair, allowing visualization of the extent and location of muscular defects ( Fig. 27.2 ). Clinical guidelines support this practice and recommend considering endoanal ultrasound or other imaging in patients with reduced anal pressures who have failed conservative therapy, particularly if surgery is being considered ( ). Findings on endoanal ultrasound do not predict clinical outcomes following conservative treatment or sacral neuromodulation (SNM). Chapter 13 includes a more detailed discussion of endoanal and transperineal ultrasonography to evaluate anal sphincter defects.
Magnetic resonance imaging.
Magnetic resonance imaging (MRI) can also be used to identify sphincter anatomy and defects, as it identifies external anal sphincter atrophy and can differentiate a scar from a tear. Because of high cost and high interobserver variability in pelvic MRI interpretation, endoanal ultrasound is preferable in most cases ( ).
Anorectal physiology testing.
Anorectal physiology testing may include manometry, rectal sensation testing, and pudendal nerve studies. Anorectal function is most often assessed by anorectal manometry (ARM), which provides quantitative measurement of the resting anal pressure generated mainly by the internal anal sphincter and the squeeze pressure generated by the external anal sphincter. ARM also provides information about the length of the anal canal, rectal sensitivity, rectal compliance, and the integrity of the rectoanal inhibitory reflex. A short anal canal and/or decreased resting and squeeze pressures are found in the majority of patients with fecal incontinence.
Rectal sensation can be studied by inserting a balloon and determining the minimal volume that the rectum can sense, then sequentially inflating the balloon to a volume that cannot be tolerated. Increased rectal sensitivity signals a rectal reservoir that does not appropriately store stool and may push the fecal bolus past sphincter muscles, even if the sphincter muscle pressures are adequate. Pudendal nerve terminal motor latency can be determined using an electrode attached to a glove inserted into the anal canal. A prolonged conduction in the pudendal nerve may signal damage to the innervation of the external sphincter and puborectalis muscle.
Anorectal physiology tests can provide information about specific elements of anorectal dysfunction, and thus contribute to treatment planning, particularly in more complex patients. However, the clinical utility of ARM is questionable, as its results do not consistently correlate with fecal incontinence severity or predict treatment outcomes. Most current practice guidelines do not recommend routine use of ARM in patients with fecal incontinence ( ; ). Based on moderate-quality evidence, an American College of Gastroenterology Clinical Practice Guideline ( ) recommended the use of ARM and balloon expulsion and rectal sensation tests in patients who do not respond to conservative treatments. Pudendal nerve latency results also do not predict treatment success, and this test is not recommended for most patients.
Defecography.
Defecography is indicated if rectal prolapse or internal intussusception (occult prolapse) is suspected. Of note: if fecal incontinence is severe, the rectal contrast may leak before initiation of the test, and results will be of limited value. See Chapter 13 for a more thorough discussion of defecography.
Nonsurgical treatment
Fig. 27.3 presents a stepwise algorithm for clinical management of patients with fecal incontinence recently proposed by . Treatment should begin with patient education, the identification of possible food triggers to loose stools and fecal urgency (e.g., fructose, lactose, caffeine), and conservative approaches, initially focusing on dietary changes and supplements to manage stool consistency, antidiarrheal medications, and pelvic floor strengthening (physical therapy/biofeedback). The cause of fecal incontinence is often multifactorial, so no single therapy will benefit all patients. Expert opinion suggests at least 3 months of conservative therapy including stool bulking and pelvic floor strengthening should be pursued prior to offering more invasive treatment options ( ).
Dietary and medical treatments
Dietary and medical treatments of fecal incontinence primarily focus on fiber supplementation to increase stool bulk and reduce watery stools, anticonstipation efforts (increased fluid and fiber, and/or laxatives) in patients with hard consistency stools, and antidiarrheal medications in those with loose stools. Because of their low risk, such conservative measures are recommended as initial treatments; however, the evidence base supporting their use is relatively sparse ( ; ).
The use of fiber bulking agents, such as psyllium husk (Metamucil; Procter & Gamble, Cincinnati, OH) and methylcellulose (Citrucel; GSK, Philadelphia, PA), can change stool consistency, making it firmer and more easily controlled. One small trial found psyllium to be superior to other fibers (methylcellulose and gum arabic) and to placebo in terms of reducing the frequency of fecal incontinence. Participants reported a 51% reduction in fecal incontinence episodes per week after treatment with psyllium, compared with a 32% increase, 20% reduction, and 11% reduction in the methylcellulose, gum arabic, and placebo groups, respectively ( ). Gradually increasing fiber intake may help reduce side effects such as abdominal distension and bloating. For example, we recommend starting with a teaspoon of psyllium daily and working up to a tablespoon up to two times daily as tolerated. If one fiber causes side effects, sometimes another will be better tolerated.
Agents designed to slow down the intestinal tract may also help with stool control. Even in patients without diarrhea, these agents may cause slight constipation, improving continence. Loperamide hydrochloride (Imodium; Johnson & Johnson, New Brunswick, NJ) is most often prescribed in this category. Loperamide prolongs intestinal transit time, allowing fecal volume to be reduced (secondary to the increased time allowed for removal of fluid from stool) and bulk density to be increased. It also increases rectal compliance, which decreases urgency. The dosage can be individualized for each patient, and it can be taken regularly or as needed. If patients have particular trouble after meals, 2 to 4 mg may be given before a meal to decrease the chance of stooling. The maximum daily dosage is 16 mg. A double-blind, randomized crossover trial compared the efficacy of psyllium and loperamide and found both to be similarly efficacious in reducing fecal incontinence episodes, but side effects were more common during loperamide treatment (29% of participants reported constipation) ( ).
Diphenoxylate hydrochloride with atropine sulfate (Lomotil; Pfizer, New York, NY) can also be used to treat fecal incontinence, especially if diarrhea is a primary contributor to the incontinence. It is dosed similar to loperamide, with one or two 2.5-mg tablets taken up to four times daily. As with loperamide, the dosing must be individualized, and the most common side effect is constipation. Other less commonly used agents that focus on control of diarrhea may include cholestyramine, anticholinergic agents, and codeine. The anticholinergic agent darifenacin showed preliminary but encouraging results in an open-label, prospective study of 32 women with double urinary and fecal incontinence. Following 8 weeks of 15 mg darifenacin daily, 19 subjects reported reduced frequency of fecal incontinence and urinary symptoms and improved quality of life ( ).
Pelvic floor muscle exercises and biofeedback
Pelvic floor muscle rehabilitative treatments are another mainstay of conservative treatment for fecal incontinence. Despite conflicting evidence in support of their effectiveness, these treatments are safe and low cost. Treatments in this category are variable and may include patients performing unsupervised pelvic floor exercises (“Kegels”) or engaging in supervised pelvic floor muscle training/exercise programs, often with a physical therapist. Electrical stimulation therapy can be used with either approach. These treatments typically focus on strengthening the external anal sphincter and pelvic floor muscles. Pelvic floor muscle training can also be augmented with manometric or electromyography (EMG)-assisted biofeedback, a type of neuromuscular retraining. In addition to strengthening the anal sphincter and pelvic floor muscles, biofeedback programs also aim to improve coordination of rectal distension and anal sphincter contraction and to improve sensation of stool in the rectum.
For biofeedback-assisted training, a balloon is placed in the rectum to simulate stool. Anal sphincter contraction is measured with a different balloon in the anal canal, by an anal plug, or by perianal surface electrodes. When contraction of the sphincter muscles is initiated, the patient observes this on the monitor. Visual (and, in some systems, auditory) feedback is given regarding contraction of the external sphincter. For sphincter strengthening, patients are encouraged when the proper sphincter response is made. They can then exercise the muscle by replicating this type of contraction outside the therapy session to increase the strength of the striated muscle.
Rectoanal coordination uses the same equipment. The goal is to train patients to achieve maximum voluntary squeeze in less than 1 second after the balloon is inflated in the rectum by consciously contracting the sphincter muscles. This method is customized for each patient, and patients may need one or more sessions to be able to perform the maneuver correctly at home. Rectal sensory perception is used to teach patients to sense smaller volumes of stool. The patients are urged to defecate with the balloon in the rectum, and observe this on the monitor. Gradually, the volume in the balloon is decreased, and patients learn to sense smaller volumes with less rectal distension. In one study, found that anal squeeze pressures, duration of squeeze, and capacity to retain liquid increased after biofeedback, and these findings correlated with a decrease in the number of episodes of fecal incontinence. However, these results have not been replicated.
Clinical trials for fecal incontinence comparing pelvic floor exercises, electrical stimulation, and biofeedback methods have reported conflicting results, possibly because of a lack of standardization in treatments and outcomes ( ). One well-performed trial demonstrated superior outcomes for biofeedback compared with pelvic floor exercises alone in patients with at least weekly fecal incontinence unresponsive to other conservative measures (76% of biofeedback patients vs. 41% of pelvic floor exercise patients were improved at 3-month follow-up, P < .001) ( ). randomized 171 patients to four treatment groups: (1) standard care (dietary and behavioral education, medications); (2) standard care plus instruction on pelvic floor exercises; (3) standard care plus biofeedback; and (4) standard care plus biofeedback and the use of a home EMG biofeedback device. In contrast to the previous study’s findings, biofeedback was not superior to standard care or to standard care with pelvic floor exercises, with equal numbers (54% vs. 53%) in the biofeedback and nonbiofeedback groups reporting improvement at 3 months. A systematic review of biofeedback and electrical stimulation by found sufficient evidence for the efficacy of biofeedback plus electrical stimulation in treating fecal incontinence. In addition, amplitude-modulated medium-frequency stimulation, also termed premodulated interferential stimulations, combined with biofeedback was superior to both low-frequency electrical stimulation and biofeedback alone. A randomized trial testing four different pelvic floor strengthening with biofeedback protocols that varied the number of in-person visits (from one to four) found that all were similarly effective, but that patient satisfaction was higher with more face-to-face contact ( ).
A recent multicenter, randomized factorial trial compared four different nonsurgical interventions in 300 women with fecal incontinence: oral placebo plus education only, placebo and ARM-assisted biofeedback, loperamide plus education only, and loperamide and ARM-assisted biofeedback ( ). After 24 weeks, all groups showed improvement in fecal incontinence severity score and bowel diary outcomes, but there were no differences between treatments (loperamide vs. oral placebo, biofeedback vs. education, loperamide and biofeedback vs. oral placebo, and biofeedback vs. loperamide plus education). The results can be partially explained by the fact that the control group, which received placebo plus education, responded better than anticipated, emphasizing the importance of patient education.
Pelvic floor muscle exercises are often grouped together with other conservative treatments. A recent randomized trial tested a group behavioral intervention (“Mind Over Matter: Healthy Bowels, Healthy Bladder”) led by a trained community member ( ). Older women with fecal and/or urinary incontinence were randomized to the intervention or a waitlist control group. The program provided education and promoted evidence-based self-management strategies and behaviors, including pelvic floor muscle exercises, dietary changes for optimization of stool consistency with gradual fiber supplementation, fluid adjustment to avoid bladder irritants and optimize fluid intake, and bladder training techniques. Both urinary incontinence and fecal incontinence improved for the intervention compared to control (71% vs. 23%, P < 0.001 and 55% vs. 27%, P < .005, respectively), offering a feasible community-based treatment.
Devices
Passive barrier devices include anal plugs and a vaginal bowel control device. These devices offer another conservative approach for managing fecal incontinence, although their use has not been widely adopted as yet. Evidence supporting these treatments remains limited, but risks appear to be low.
Anal plugs are simple devices that act as barriers to stool leakage. The plugs can be inserted after a bowel movement and removed manually or expelled during defecation. The Peristeen anal plug (Coloplast, Humlebaek, Denmark), available in Europe and Canada only, comes in two sizes and is made of soft foam with a water-soluble film that dissolves in the anal canal. The plug expands to three to four times its size and can be retained for 8 hours. Limited evidence suggests that long-term use is successful and tolerated in select patients and may reduce fecal incontinence symptoms ( ). Another anal plug (Renew; Renew Medical, Foster City, CA) is a soft silicone plug, self-inserted with the use of a fingertip applicator and available in two sizes. In a prospective multicenter study ( n = 91), 80% of enrolled participants completed 12 weeks of device use, and 78% of the completers reported more than a 50% reduction in frequency of fecal incontinence episodes ( ). Adverse effects were generally mild, and limited to anal irritation and rectal pressure or discomfort.
A vaginal bowel control system (Eclipse System; Pelvalon, Sunnyvale, CA) was introduced recently. The vaginal silicone-coated device contains a dynamic balloon oriented posteriorly that reversibly compresses the rectum to aid in continence. In a prospective multicenter study, 62% of women enrolled achieved a successful fit. Some 53 of 73 (73%) women who entered the treatment phase had success at 3 months (>50% reduction in fecal incontinence episodes), and 74% continued therapy through 12 months with greater than 90% satisfaction ( ). Adverse effects occurred in 38% of women during the treatment period, were generally mild, and most often included pelvic or vaginal discomfort or irritation and vaginal wall injury.
Bowel management
Some patients find that daily enemas with approximately two pints of tap water, usually at the same time each morning just after eating, induce a bowel movement and empty the rectum. A cone-tipped catheter (the same type used for colostomy irrigation) may be helpful for incontinent patients to instill an enema so that it does not run out with instillation. Some advocate inserting a glycerin or bisacodyl suppository 20 to 30 minutes after eating, along with abdominal massage, to induce a bowel movement daily. With either method, bulking agents can be used, in addition to medications, to stop stooling in between desired defecation.
For patients with fecal incontinence associated with more severe dysfunction, such as neurogenic bowel, there is also a designated colonic irrigation system that combines tap water irrigation with a rectal balloon (Peristeen System; Coloplast, Humlebaek, Denmark). Inflation of the balloon prevents the water from leaking, and deflation results in irrigation of the rectosigmoid.
Procedures and surgery
Perianal bulking injections
Anal canal bulking injections have been performed using a wide variety of substances (including autologous fat, synthetic bovine dermal collagen, Teflon, silicone, and carbon beads) and techniques. In 2011 the US Food and Drug Administration (FDA) approved the use of dextranomer microspheres in non–animal-stabilized hyaluronic acid (NASHA Dx) (Solesta; Salix Pharmaceuticals, Raleigh, NC) injected into the anal canal as a treatment for fecal incontinence. In a multicenter randomized study, 52% of patients injected with NASHA Dx had a greater than 50% reduction in fecal incontinence episodes compared with 31% of those receiving a sham injection, and complications were rare ( ). About 80% of the patients in both treatment arms had a second injection because of inadequate response. A Cochrane review concluded that NAHSA Dx may confer short-term benefits to just over half of patients treated ( ). Longer-term results subsequently published suggested that reductions in fecal incontinence episodes, as well as quality-of-life improvements, were sustained at 24 and 36 months in those patients with initial success ( ). This and other smaller and uncontrolled studies support modest improvements in symptoms after perianal bulking injections with some sustained effects.
NASHA Dx is currently the only FDA-approved bulking product for fecal incontinence. Perianal bulking agents are administered in an outpatient setting and do not require anesthesia. The injection kit comes as four preloaded syringes holding 1 cc of the NASHA Dx gel. The gel is injected into the submucosal space in four areas 5 mm above the dentate line. The procedure is carried out in the office using a large beveled anoscope. This is a safe procedure, with minor bleeding being the most common complication, although rarely patients have developed a postprocedure abscess.
Although the assumption is that bulking agents improve closure of the anal canal, posttreatment anal manometry failed to show improvement of resting and squeeze pressures ( ). The original NASHA Dx trial included patients with severe fecal incontinence and with no sphincter defect, and it is unknown if patients with sphincter defects or with mild to moderate fecal incontinence will benefit. Clinical practice guidelines from the American College of Gastroenterology provide a weak recommendation that injectable anal bulking agents may have a role in treatment of fecal incontinence in patients who do not respond to conservative treatments, including biofeedback therapy ( ; ).
Sacral neuromodulation
SNM was approved by the FDA for treatment of fecal incontinence in 2011. The sacral nerve stimulation procedure, involving implantation of a wire electrode near the third sacral nerve root attached to a subcutaneous implantable pulse generator, is essentially the same as when used for treatment of urgency urinary incontinence. Chapter 32 includes a detailed discussion of procedure steps, reviewed briefly here.
As in treatment of urgency urinary incontinence, the procedure consists of two parts. Initially, a test phase is completed with placement of a sacral stimulation lead through the S3 sacral foramen. This can be performed using a less-invasive office-based percutaneous nerve evaluation (PNE) procedure, placing a temporary electrode wire with or without fluoroscopic guidance, or as an outpatient stage I procedure with placement of a permanent, self-anchoring lead ( Fig. 27.4 ), which is confirmed radiologically ( Fig. 27.5 ). During the 1- to 2-week test phase, the lead is connected to a temporary stimulation device, and the patient reports episodes of fecal incontinence and stool consistency in a diary. If the patient reports a greater than 50% improvement in frequency of fecal incontinence episodes compared with a preprocedure diary, the permanent neurostimulator is implanted in the upper buttock region. If the improvement seen is not sufficient, or if no improvement occurs, the lead is removed. When the staged approach is used, stage II is typically performed about 2 weeks after stage I to lessen the chance of infectious complications.
