Pelvic Floor Disorders: Surgical Approach

8. Fecal Incontinence

Carlo Ratto , Angelo Parello, Lorenza Donisi, Francesco Litta, Veronica De Simone and Giuseppe Zaccone

(1)

Department of Surgical Sciences, Catholic University, Rome, Italy

Carlo Ratto

Email: carloratto@tiscali.it

Abstract

Fecal incontinence (FI) is a frequently occcurring, distressing condition that has a devastating impact on the lives of patients. However, patients are typically embarrassed and reluctant to acknowledge this disability, so they do not seek a cure and remain socially isolated. The exact incidence of FI is not known, because of the reluctance of patients to seek help from their physicians. Most epidemiological studies suggest a prevalence of as high as 2% of the general population; however, when patient interviews ask specific questions about FI, the rate is usually significantly higher. Women seem to be at higher risk of FI, mostly because of obstetric damage to anal sphincters; however, during the last decade there has been increasing interest in types of FI with nontraumatic causes, as these have been shown to occur in significant numbers. Older subjects are at a very high risk of FI, especially those that present with disabilities or are institutionalized. Young patients are also often affected. This results in a significant economic impact for society because of the direct and indirect costs, and also for intangible reasons. Since FI can be the result of various pathophysiological conditions, and a variety of risk factors can cause a wide range of ways in which patients develop the inability to control the passage of feces, an accurate diagnostic work-up of each patient is fundamental.

8.1 Introduction

Fecal incontinence (FI) is a frequently occcurring, distressing condition that has a devastating impact on the lives of patients. However, patients are typically embarrassed and reluctant to acknowledge this disability, so they do not seek a cure and remain socially isolated. The exact incidence of FI is not known, because of the reluctance of patients to seek help from their physicians. Most epidemiological studies suggest a prevalence of as high as 2% of the general population; however, when patient interviews ask specific questions about FI, the rate is usually significantly higher. Women seem to be at higher risk of FI, mostly because of obstetric damage to anal sphincters; however, during the last decade there has been increasing interest in types of FI with nontraumatic causes, as these have been shown to occur in significant numbers. Older subjects are at a very high risk of FI, especially those that present with disabilities or are institutionalized. Young patients are also often affected. This results in a significant economic impact for society because of the direct and indirect costs, and also for intangible reasons. Since FI can be the result of various pathophysiological conditions, and a variety of risk factors can cause a wide range of ways in which patients develop the inability to control the passage of feces, an accurate diagnostic work-up of each patient is fundamental. Although not fully accepted, a multimodal diagnosis, using a multiparametric evaluation, seems to allow a better understanding of FI pathophysiology and address the optimal treatment. Optimal treatment is the most important challenging aspect of FI management. Indeed, there is currently a wide range of therapeutic options available, including conservative, rehabilitative, and surgical procedures. The aim of surgery might be correction of a defect, or improvement of a dysfunction in continence control when the sphincter complex is intact, or replacement of a largely fragmented or non-functioning sphincter. Making the correct choice is pivotal to the successful management of this condition. Although a number of reports are available regarding results of different surgical procedures, there is a lack of evidence from randomized controlled studies, making the choice of procedure very difficult.

8.2 Diagnostic Work-up

Anal continence is maintained by the activity of complex anatomic and physiologic structures (anal sphincters, pelvic floor musculature, rectal curvatures, transverse rectal folds, rectal reservoir, and rectal sensation). It is also dependent on numerous other factors, such as stool consistency, the mental faculties and mobility of the patient, available facilities, and social convenience. Only if there is effective coordinated integration of these factors can defecation proceed normally. FI is the result of disruption of one or a few of these different entities: it can have a multifactorial pathogenesis, and in many cases it is not secondary to a sphincter tear. The disruption can lie in alterations that are intrinsic to the anorectal neuromuscular structures of continence control, or extrinsic to them, also involving extrapelvic control mechanisms. The primary aim of an effective therapeutic approach is the improvement, or better still the resolution, of this distressing condition. Different forms of therapy are currently available, so physicians have to select the most appropriate treatment for each patient. Consequently, the diagnostic work-up is fundamental in order to assess the functional condition of every part involved in the continence mechanism, and identify the presumed cause(s) of incontinence. Several specific tests have been designed that are instrumental in FI diagnosis; these are available in a clinical setting for investigational purposes. However, there is disagreement among clinicians on the choice and timing of diagnostic procedures.

8.2.1 Clinical Assessment

Investigation of the patient’s history is of utmost importance. It is important to ascertain the characteristics of normal defecation (occurring without incontinence). Then, efforts should be made to identify the symptoms of pathogenic significance and define the type of FI (urge incontinence, passive incontinence, fecal soiling, or seepage). Thereafter, timing, duration, and frequency of FI, type of stool lost, use of pads, rectoanal sensation during normal defecation and FI episodes, and influence on health status and quality of life are all fundamental features to be ascertained. They should be related to possible events in the patient’s history, including metabolic and neurological diseases, obstetric and pelvic surgery, neurosurgery, pelvic trauma, chronic inflammatory bowel disease, pelvic irradiation, psychiatric conditions, and physical and sexual abuse.

An interview with the patient could be used effectively in the physical examination of the patient. Exploration or a digital maneuver should be performed in order to determine physical alterations of the anus, perineum, and pelvis, and elicit specific reflexes.

The symptoms and signs of the patient should be considered in order to classify the grade of FI, in order to evaluate the severity, and also for future assessment of the effectiveness of therapeutic approaches; a number of scales have been proposed for FI grades. Finally, the patient’s quality of life must be considered in both the evaluation of FI severity and the assessment of treatment; numerous criteria have also been proposed for this parameter.

8.2.2 Physiological Investigations

The primary aims of the tests used for FI patients are to better elucidate the pathophysiology and to address the treatment. The assessment must address both the function (mostly provided by anorectal manometry and rectal sensation investigation, and anorectal electrophysiology) and the structure (obtained by endoanal ultrasound and/or magnetic resonance) of all components, both pelvic and extrapelvic, involved in continence mechanisms. As a result of the multifactorial nature of FI, no single test is sufficient on its own, and a combination of investigations is needed. When FI occurs with diarrhea, other possible causes should be explored by use of endoscopy and stool tests. When a clinical examination suggests that FI could be secondary to metabolic or neurological causes, or neurosurgical causes, trauma, bowel inflammation or irradiation, or psychiatric reasons, specific investigations should be carried out.

Diagnostic assessment should be used to plan the treatment. In fact, anorectal testing can add to diagnostic information in 19–98% of patients, influence the management plan in 75-84% of patients, and alter the management plan in 10–19% of patients, when compared with a clinical assessment alone.

8.2.2.1 Anorectal Manometry and Rectal Sensations

Anorectal manometry and rectal sensation tests are usually performed at the same time, and include the evaluation of rectoanal reflexes and rectal compliance. Although they are the most frequently used diagnostic procedures in proctology, particularly in FI patients, they are carried out using a variety of techniques because of wide technical variations concerning computer software, probes (water perfused or solid state; unichannel or multichannel; difference in number, location, and shape of openings; difference in location and balloon material), acquisition modality of pressures (by pull-through or stationary), and sensations (by inflation using either air or water, or using a barostat); because of these technical differences it is not possible to precisely define either a standard examination or normal values.

In incontinent patients, both resting and squeeze pressures should be calculated; the investigator should be very careful to evaluate not only the numeric value (i.e., mean or median) but also consider the pressure profiles, giving information on asymmetry in the anal canal (due to a limited lesion of the internal or external anal sphincter), or decreased external anal sphincter endurance to muscle fatigue during prolonged squeeze. Based on a multichannel acquisition of resting pressure profile, it is usually possible to visualize a “vector manometry”. On the other hand, in a number of incontinent patients, resting and/or squeeze pressures can be normal, and related to a nontraumatic pathophysiology of their incontinence. Although the rectoanal inhibitory reflex is routinely evoked, its role in pathophysiological assessment of FI is not well established. Other reflexes (i.e., coughing) should be elicited to investigate possible spinal cord lesions. Rectal sensations are very important parameters that should be investigated in FI patients (threshold and urge sensations, and maximum tolerated volume).

8.2.2.2 Endoanal Ultrasound

Endoanal ultrasound (EAUS) is used to investigate the anal canal and rectum with specifically designed ultrasound probes and software. The most useful probes are those that include radial probes with a full 360° field of view, and a frequency range between 5 and 16 MHz. During the examination, the probe is inserted into the anal canal, reaching the puborectalis sling showing the “U”-shaped aspect. From this level, a manual or mechanical pull-through examination is performed to evaluate the distinct layers and structures of the anal canal: submucosa, internal anal sphincter, longitudinal sphincter, external anal sphincter, puborectalis, anococcygeal ligament, puboanalis muscle, and perineal body. More recently, the EAUS technique has been developed to obtain a three-dimensional imaging (3D-EAUS), obtained from numerous axial, rapidly acquired, two-dimensional (2D) slices. With 3D-EAUS, the operator is able to navigate inside the 3D structure to observe the anal canal not only in axial views, but also longitudinal and oblique views. A sphincter lesion appears as a hypoechoic area involving a circumferential segment of the internal anal sphincter, external anal sphincter, or both. Then, EAUS is particularly useful in differentiating FI patients with and without sphincter tears.

8.2.2.3 Anorectal Electrophysiology

Anorectal electrophysiology (AREP) includes tests that are used on patients who have already been investigated with history and physical assessment and other procedures (mainly ARM and ultrasound), in whom pelvic muscular and/or nervous functions seem to be altered. Electrophysiological studies are usually carried out with a neuromyograph system equipped with software dedicated to anorectal physiology, and cables and electrodes to evaluate electrical muscle activity and nerve functionality.

The purpose of electromyography (EMG) is to investigate the electrical activity of the EAS and the other striated pelvic floor muscles, at rest and during squeezing and straining. Muscle denervation or reinervation can be found in incontinent patients.

Threshold mucosal sensation can be evaluated with electrostimulation not only in the rectum (as with anorectal manometry), but also in the anal canal, using a bipolar ring electrode. Pudendal nerve terminal motor latency is measured with a disposable St Mark’s pudendal electrode, allowing the evaluation of the integrity of the pelvic floor. The evoked potentials can be obtained by stimulation of the cortex or sacral roots in order to assess the central and peripheral motor (motor-evoked potentials) and somatosensory (somatosensory-evoked potentials) pathways.

8.2.2.4 Defecography and Magnetic Resonance

Defecography is able to assess pelvic floor physiology, recording motion at rest, and when squeezing, straining, and coughing. The anorectal angle should be calculated. Perineal descent can be found frequently in incontinent patients. Moreover, rectorectal intussusception, rectocele, enterocele, or sigmoidocele can also be diagnosed; pelvic muscle dyssynergia also needs to be adequately evaluated because it can cause continence disturbances.

Magnetic resonance (MR) imaging of anal sphincters has been evaluated using phased-array coils or an endoanal coil; controversy exists about preference between the two types. More recently, it has been suggested that MR defecography be included in the diagnostic work-up of FI patients in order to detect previously missed functional alterations of anterior, middle, or posterior pelvic compartments.

8.3 Treatment

Criteria for selection of patients for treatment of FI are of central importance. These criteria should take in account not only the possible impact of a certain therapy on FI pathophysiology in a particular patient (resulting from the investigations), but also the psychological aspects caused by FI and those that might possibly be related to future treatment.

8.3.1 Medical Therapy

There is little evidence published regarding medical therapy for FI; therefore it is the subject of debate and treatment is often pragmatic. It includes diet and drugs, supportive measures, rehabilitation, and biofeedback. These treatments are usually chosen either for “elective” reasons or for patients who cannot be treated by a surgical approach. Poor clinical condition of a patient, limiting anesthesia and/or surgery, could be a valid criterion for a nonoperative approach, while a patient’s age might also be relatively limiting. Psychological problems or psychiatric disturbances should suggest avoiding very complex surgical procedures requiring the patient’s compliance. Specific bowel diseases (chronic inflammatory diseases, irritable bowel syndrome), with uncontrolled symptoms, should contraindicate a major surgical approach. The choice of treatment for life-threatening clinical conditions (evolving diseases, chronic diseases, not radically treated neoplasms) should consider the patient’s life expectancy and the possible benefits in quality of life.

An “elective” indication for medical therapy should include minor FI without physiologic or morphologic alterations; in cases with minor abnormalities, a medical approach could be considered as a first-line intervention. Individuals with continence dysfunctions related to altered quality of feces (i.e., diarrhea) should expect to have benefits from conservative treatment; the patient should be encouraged to improve perianal hygiene, use carefully absorbent cotton diapers and tampons, and reduce intake of or avoid foods inducing loose stools and increasing gastrointestinal transit and gas production (milk derivates, legumes, excess fiber). Diarrhea should be fully investigated and, consequently, treated with medication when appropriate. Specific drug treatment should be initiated in cases of chronic bowel diseases. Also the pathophysiology of the soiling should be fully elucidated in order to inform the choice between operative and nonoperative treatment.

Pelvic floor rehabilitation, including biofeedback, kinesitherapy, sensory retraining, and electrostimulation, is frequently regarded as a first-line treatment for FI. However, disagreement exists about indications for rehabilitative techniques.

8.3.2 Surgical Treatments

Until recently, in cases of intractable poor FI, the criteria for selecting patients for surgical treatment were sphincter lesions or pudendal neuropathy with perineal descent and altered anorectal angle. In the former condition, a sphincteroplasty was indicated in cases of a limited lesion without alteration of pudendal nerve terminal motor latency, while a sphincter replacement operation (dynamic graciloplasty, artificial sphincter, or gluteoplasty) was indicated for presence of a wide lesion, plurifragmented sphincters, or failure of previous sphincteroplasty. In the latter condition, a postanal repair was indicated. In 1995, sacral nerve stimulation was introduced into the wide range of treatments available for FI, and this resulted in a significant change in the selection criteria. Recently, there has been renewed interest in bulking agents, and a new implantable system, based on a self-explandable prosthesis (Gatekeeper), has been introduced.

8.3.2.1 Sphincteroplasty

Patients with sphincter lesions caused by an obstetric trauma (third-degree and fourth-degree tears) have undergone elective sphincteroplasty. Edge-to-edge approximation or an overlapping of external anal sphincter can be used in this technique. Immediate repair, at the time of delivery, or delayed for a period of 24 h has been suggested to produce the best results. However, sphincteroplasty is frequently performed a few decades after childbirth, when the patient present clinically with FI. In order to improve the long-term results of sphincteroplasty alone, which can sometimes be of limited success, this operation can been performed within a total pelvic floor repair or with anterior levatorplasty.

8.3.2.2 Postanal Repair

Patients with neuropathic FI, associated with perineal descent and without sphincter lesions seem, theoretically, to present with the best indications for postanal repair. However, considering the limited long-term effectiveness of this treatment, these patients could be more effectively treated by other procedures. Indeed, indications for postanal repair have been significantly reduced over time. It has been advocated as a part of a total pelvic floor repair in conjunction with anterior levatorplasty.

8.3.2.3 Dynamic Graciloplasty, Artificial Bowel Sphincter, and Gluteoplasty

These procedures must be regarded as major sphincter replacement operations, used only for patients with very severe FI caused by a large sphincter lesion (more than half of the sphincter circumference) or fragmented sphincters not amenable to either sphincteroplasty or other surgical approaches (i.e., sacral nerve stimulation, SNS). It can also be indicated in cases in which previous sphincteroplasty has failed (and there is no indication to repeat it), and the patient is not suitable for SNS. Moreover, if severe FI is a consequence of neuropathy or anorectal malformation, one of these operations could be performed (specifically, in cases of neuropathy, when SNS has failed). The only major contraindications to sphincter replacement procedures are very poor chronic bowel diseases causing intractable defecation dysfunctions (severe diarrhea, as well as severe constipation) and coexistence of rectal prolapse, intussusception, rectocele, or enterocele.

Although the indications for dynamic graciloplasty, artificial bowel sphincter, and gluteoplasty overlap, there are various differences between the procedures related to the surgeon’s preference and expertise, techniques and materials used, and evaluation of perioperative morbidity and long-term results.

8.3.2.4 Sacral Nerve Stimulation

SNS now plays a central role in the algorithm of FI management. Even though it has been only recently applied clinically to anorectal dysfunctions, the use of this approach has rapidly expanded and the number of acceptable indications has increased. Initial applications concerned patients with dysfunctions of unlesioned striated anal muscles, then those with a prevalent neurogenic etiology. Thereafter, since there has been progress in clinical use and understanding mechanisms of action, SNS has been expanded to other indications including idiopathic sphincter degeneration, iatrogenic internal sphincter damage, partial spinal cord injury, scleroderma, limited lesions of internal or external anal sphincters, rectal prolapse repair, and low anterior resection of the rectum.

8.3.2.5 Injectable and Implantable Agents

This treatment approach is regarded as attractive because it is not invasive. However, only very accurate patient selection can produce positive effects on FI using bulking agents. Usually, patients with either a limited internal sphincter lesion or a weak anus without tears are indicated for this type of treatment. Moreover, individuals who cannot be considered for other major surgical approaches because of their general poor clinical condition could be suitable for the injection of bulking agents. The increasing variety of agents proposed and used to create a bulking effect, with different methods of injection (through the anal mucosa, or transsphincteric), different placement sites (submucosal or intersphincteric), and different check procedures (digital examination or EAUS), has not produced comparable criteria for selecting the most appropriate approach.

More recently, another procedure has been deveopled for the implantation of a specifically designed prosthesis: the Gatekeeper System. The prosthesis is small, thin, and solid when implanted, becoming larger and soft in contact with organic liquids when inserted into the anal canal, within 24–48 h after implantation. The procedure provides for the implantation of 4–6 prostheses for each patient, in the intersphincteric space, using a dedicated delivery device. The prostheses are visible on sonography, and this makes it possible to follow and control the position of the prostheses sonographically during follow-up. The main characteristic shown by the Gatekeeper prostheses is the stability of their position in the sites of the implant over time, because they are not biodegradable.

8.4 Treatment Evaluation

A variety of factors can affect the evaluation of the effectiveness of a certain therapy for FI. Identification of factors reflecting the impact of the treatment and methods for measuring the improvement obtained are of crucial importance. These should be derived from well-controlled studies with a sufficiently large number of patients that have been selected using strict criteria. However, the results of published reports are frequently affected by non-standardized patient selection. Also, the criteria used to define the response to the therapy are not standardized. This could depend on what is taken to be the end point of the particular treatment: improvement of symptoms (i.e., reduction of FI episodes, improved control of solid versus liquid stools versus gas, ability to postpone defecation), or improvement of patient’s quality of life, or improvement of multifactorial aspects (i.e., improvement of scores), or normalization of physiology parameters (i.e., manometric, electrophysiologic, ultrasonographic, etc.).

It is debatable whether a relative improvement of at least 50% for FI could be considered a good response; in fact, for a patient treated for very severe FI, reduction of 50% in the number of FI episodes (for instance, from ten down to five episodes per week) is probably not enough to significantly improve the patient’s poor quality of life and lifestyle (e.g, need to wear pads, staying close to a bathroom, confined to staying at home, etc.). Moreover, even if perfect control of solid stools has been regained after treatment, incontinence to liquids or gas remains very detrimental to the quality of life of the patient. Because there is disagreement on the clinical parameters to define a response to treatment, the data available in reports should be evaluated carefully and critically.

In addition to this, the scoring systems used for FI measurement are not the same as those used in quality-of-life questionnaires. They are often too vague and subjective. A patient’s “satisfaction” would be probably the most comprehensive parameter to reflect success of the therapy, but it is difficult to quantify. Moreover, each scoring system and questionnaire needs to be validated according to specific social, cultural, and environmental factors.

Physiological parameters are used to demonstrate the objective impact of a treatment. However, conflicting data are frequently obtained when a single parameter is considered, because of the multifactorial origin of FI. Moreover, the outcome of a particular treatment can vary in different subgroups of patients, as each group could have particular physiological features.

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