Introduction and Incidence
Fecal incontinence may be defined as the inability to voluntarily control the release of flatus or stool until a socially convenient time and place. Fecal continence, which is learned in childhood, is one of the most important social milestones in development, and its loss is a devastating handicap. The prevalence of incontinence varies by gender, age, and definition; however, as many as 2% of women regularly experience difficulty controlling stool and at least 10% have difficulty controlling flatus. Incontinence is more common in parous women because childbirth is the most common cause of pelvic floor injury. Menopause also contributes through diminished trophic effects of estrogen on pelvic connective tissues, and symptoms frequently become manifest in the sixth or seventh decade. The overall cost of fecal incontinence to society is unknown, but the magnitude of the problem is illustrated by the fact that fecal incontinence is the second leading reason for admission of elderly persons to nursing homes—a reason more common than dementia. The hidden cost is a reduction in quality of life and lost opportunities resulting from this most embarrassing of symptoms.
Causes
Fecal continence depends on the presence of an intact anal sphincter mechanism, coupled with adequate rectal compliance and a normal volume and consistency of stool. A wide variety of anatomic and physiologic factors can alter continence, particularly changes in colonic transit and stool consistency, abnormal rectal physiology, abnormal anorectal sensation, pelvic floor denervation, and disruption of the integrity and function of the internal and external anal sphincters. In general, the four main causes are (1) abnormal stool volume and consistency; (2) neurologic disorders leading to sphincter weakness; (3) anatomic defects in the anal sphincters; and (4) abnormal rectal physiology. Because these problems often overlap, each area must be addressed to ensure accurate diagnosis and effective treatment.
Assessment
Many scoring systems have been proposed to categorize the severity of fecal incontinence. The use of such systems is important for accurate patient assessment, medicolegal documentation, and objective evaluation of treatment outcomes. Each scoring system has strengths and weaknesses. The ideal system would accurately and reproducibly describe the frequency of incontinent episodes, the degree to which patients are incontinent of gas, liquid, and solid stool, and the effect of incontinence on lifestyle. Two validated scoring systems are widely used: the Cleveland Clinic Continence Score and the St. Mark’s Continence Score. Quality of life scores should be determined independently. Use of the validated Fecal Incontinence Quality of Life symptom-specific score is helpful because it is the patient’s quality of life that is the most important determinant of the need for intervention.
Evaluation of fecal incontinence begins with a detailed interview that includes a careful medical, surgical, and obstetric history. The timing and type of incontinence should be noted, as well as the use of pads, diapers, or medications. It is important to ascertain the severity of the incontinence, which may vary from soiling to loss of a complete bowel movement, and whether the incontinence is primarily associated with urgency and the inability to hold the rectal contents or is passive. Many patients have a combination of symptoms that may include obstructed defecation with incomplete evacuation.
Obtaining a dietary history is important because many patients consume inappropriately high amounts of fermentable fiber in the mistaken belief that a “healthy diet” is required for their bowel condition. Often breakfast is omitted, particularly by working mothers, and thus the opportunity to use the gastrocolic reflex to ensure a predictable early morning bowel movement is lost.
Physical examination should include flexible sigmoidoscopy to rule out neoplastic and inflammatory disorders, with further evaluation of the small and large bowel as clinically indicated. The perineum is inspected for scars, fistulas, and adequacy of the perineal body. The presence of rectal prolapse or perineal descent is appreciated by asking the patient to bear down. Digital examination at rest and with squeeze effort permits qualitative assessment of internal and external sphincter function. The presence and extent of a rectocele or uterine prolapse should be determined.
Endoanal ultrasonography is the best technique currently available to evaluate patients for possible anatomic anal sphincter defects and should be performed in all patients with incontinence. The relationship between the extent of an individual anal sphincter defect and continence is difficult to correlate; however, defects extending to one quadrant (90 degrees) or greater usually contribute significantly to a patient’s symptoms. Defects in the external anal sphincter (EAS) are associated with urge incontinence, whereas internal anal sphincter (IAS) defects are associated with passive soiling and leakage of mucus. Occult anal fistulas and other less common pathologic conditions also may be identified using endoanal ultrasound, and three-dimensional imaging may be useful in assessing the extent of injury. In expert hands, transperineal ultrasonography provides detailed anatomic images and may allow dynamic assessment of rectocele, rectal intussusception, and levator ani injury.
Patients considering surgery because of the severity of their incontinence should undergo anorectal physiologic assessment. Anal manometry documents resting and squeeze pressures, indicating IAS and EAS function, respectively. Rectal sensation may be assessed using balloon distention to determine the volume of first sensation, volume of first urge, and maximum tolerated volume. Pudendal nerve function may be evaluated noninvasively by determining pudendal nerve terminal motor latency with a glove-mounted electrode; however, the results are not predictive of therapeutic outcome, and the technique is not routinely performed. Concentric nerve electromyography of the EAS can accurately determine the presence of motor neuropathy, and the cliteroanal reflex can be used to determine afferent and efferent conduction along the pudendal nerve and its terminal branches. In practice, such investigations are rarely performed.
Defecography provides a dynamic view of rectal function and permits identification of pelvic floor disorders such rectocele or internal intussusception that can contribute to incontinence through obstructed defecation and incomplete evacuation.
Treatment
Treatment should be individualized based on the severity of symptoms, the patient’s overall condition, and the degree to which the incontinence is affecting the patient’s quality of life.
Medical Management
True incontinence must be differentiated from pseudoincontinence, soiling of mucus or pus caused by prolapsing hemorrhoids, full-thickness rectal prolapse, or occult fistulas. In these instances, therapy is directed at the primary cause. Conservative management is appropriate for true mild incontinence and is focused on optimizing stool consistency and colonic motility. Excess fermentable fiber should be excluded from the diet and replaced by fiber supplements taken once or twice daily to provide a soft, bulky stool. Patients with loose stools should be instructed to take only enough water to dissolve the bulking agent, thus permitting maximal absorption of excess stool water. Judicious use of antidiarrheal agents such as loperamide or diphenoxylate with atropine is appropriate to decrease stool frequency. Frequently, these drugs are most helpful at bedtime or prior to planned social engagements. Loperamide has been shown to increase internal anal sphincter pressure and may help minor degrees of seepage from a lax anus. In some patients, the adult dose of loperamide (2 mg) leads to constipation, and in these circumstances, 1 mg pediatric syrup is useful. Some patients, particularly those with chronic seepage, also may benefit from regular emptying of the rectum with a small tap-water enema.
Biofeedback
Biofeedback is a dynamic technique that allows a person to learn and respond to physiologic changes in the body. In the case of fecal incontinence, patients are trained to improve voluntary anal sphincter contraction, improve rectal sensation, and coordinate squeeze efforts with rectal distention. Biofeedback represents a qualitative improvement over simple pelvic floor exercises, such as those popularized by Kegel, because the patient learns to focus efforts upon the appropriate target, the EAS, rather than the gluteus maximus. Biofeedback is painless, noninvasive, relatively inexpensive, and risk free. Rectal sensory training is accomplished by instillation of progressively smaller quantities of air into a rectal balloon.
Requirements for biofeedback therapy include motivation, the ability to follow instructions, and the ability to contract the sphincter muscle to a detectable degree. Specific indications for biofeedback include neurogenic fecal incontinence, inability to undergo surgery, and failure of sphincteroplasty. The effects of biofeedback on incontinence are reasonable, with most patients experiencing sustained improvement.
Surgery
Anal Sphincter Repair (Sphincteroplasty)
Anal sphincter injury is most commonly due to obstetric trauma, with the site of injury in the anterior quadrant of the anus. In other patients, such as those who have had previous anorectal surgery, perineal injury, or pelvic fractures, the site and extent of a suspected sphincter injury may be difficult to determine upon clinical examination, and endorectal ultrasonography may be required to define sphincter anatomy.
Acute anal sphincter injuries, particularly those that occur during childbirth, are best repaired at the time of injury. The repair should be performed under optimal conditions in the operating room, rather than in the labor ward. If an obstetric injury has been missed or the primary repair breaks down, secondary repair should be delayed until local inflammation and edema have completely resolved.
Patients undergoing elective anal sphincteroplasty may need to perform full mechanical bowel preparation; however, an enema on the morning of the surgical procedure is usually adequate. Perioperative broad-spectrum parenteral antibiotics should be prescribed. The operation may be performed with the patient in a lithotomy or prone jackknife position and the buttocks taped apart. Prior to incision, infiltration of the operative field with a 1:100,000 adrenaline solution is helpful and particularly aids in dissection of the rectovaginal septum. When the perineum is foreshortened, a curvilinear incision should be made between the anus and vagina; however, if the perineum is of adequate length, a curved incision along the posterior vaginal fourchette is associated with fewer wound healing problems. The use of stay sutures or a Lone Star retractor (CooperSurgical, Inc., Trumbull, Conn.) to retract wound edges is helpful.
Once the incision is made, sharp dissection is required to elevate anorectal and vaginal mucosa from the sphincter complex and associated scar. This process is technically the most difficult part of the procedure, and care is required to avoid “buttonholing” the rectal mucosa. The scar and sphincter mechanism are dissected laterally to the midcoronal line to a sufficient degree to allow overlap of the sphincter ends in the midline. When possible, the IAS should be separately identified and repaired. Excessive posterolateral dissection should be avoided because branches of the pudendal nerve are found in the 3 and 9 o’clock positions and may be damaged inadvertently. Cephalad dissection in the rectovaginal septum continues until the levator ani muscles are identified where they insert along the “white line” on the obturator internus muscle on each side. In cases in which the sphincter muscles are difficult to identify, it is usually possible to identify healthy sphincter in the ischiorectal fossa, away from the area of maximal scarring in the anterior midline, and dissect medially. In most instances, an overlapping sphincteroplasty, as described by Parks, is preferred. The attenuated muscle and scar are divided (preserving the scar to help prevent the suture from tearing through the muscle) and overlapped to recreate a snug anal canal ( Fig. 19-1 ). The repair is then performed with a series of absorbable horizontal mattress sutures. Many surgeons also perform an anterior levatorplasty in an effort to lengthen the anal canal; however, it is a potential cause of dyspareunia.
