Incontinence

What Is Incontinence?

Image courtesy of Diabetes.co.uk Opens in new window Incontinence is the involuntary and uncontrolled passage of urine or stool or both to an extent that cause social or sanitary difficulties. The term incontinence is a complex one and encompasses a broad spectrum of disorders with various intensities. They range from urinary incontinence and gas incontinence, through incontinence of liquid stools (soiling Opens in new window), to incontinence of solid stools (fecal incontinence Opens in new window). Urinary incontinence Opens in new window is relatively common and plagues 10–35% of adults.

Incontinence can be a significant problem for young, middle-aged, and older adults. Fecal incontinence affects 2–7% of the adult population. The range of the problem is not exactly known due to its embarrassing nature and reluctance to report stool and/or gas incontinence to physicians.

The majority of patients are women. It has been reported that 1 of 10 women suffers from various types of incontinence. Urinary incontinence Opens in new window affects approximately 13 million Americans in community and institutional settings.

Despite its prevalence, and an estimated annual cost of more than $15 billion, most affected individuals do not seek medical help for incontinence, primarily because of embarrassment or because they are not aware that help is available. When individuals do seek help, evidence exists that practitioners are hesitant or ill prepared to discuss, diagnose, or treat the problem.

Life with incontinence, even mild incontinence, can become very stressful as it threatens self-image, body image, and self-esteem Opens in new window. Concerns about having to deal with incontinence may hinder career opportunities for sufferers in the workforce.

Incontinence can be even more debilitating for women. The embarrassing loss of self-control makes a woman feel old and helpless. Outings for shopping and recreation may be planned around the availability of bathrooms. Travel to new places becomes difficult.

Having a change of clothes handy and worrying about odor are constant concerns. Worst of all, women suffering from incontinence may stop some of the daily routines they enjoy altogether; they may avoid getting together with friends or family and having sexual contact altogether. Understandably, they may feel depressed.

Many people consider adult incontinence a natural part of aging. It is not! The vast majority of older women do not have incontinence. Most people are not aware that young women can also experience incontinence. Since incontinence is so frequently associated with aging, younger women are even less likely to talk about it or seek treatment. The good news is that there are now many ways to treat women of all ages who have incontinence.

Is All Incontinence the Same?

Incontience is a symptom—the loss of urine, stool or both. When it comes to uncontrollable loss of urine, the two most common types of incontinence are loss of urine during laughing, coughing, or sneezing, called stress incontinence Opens in new window, and loss of urine preceded by a strong urge to void, called urge incontinence Opens in new window or overactive bladder.

Sometimes a patient has both types of incontinence at the same time. This combination of types of incontinence is called mixed incontinence Opens in new window.

Different types of incontinence have different causes, and different treatments solve each type.

The first step toward ending incontinence is for your physician to determine which type of incontinence you have. This begins with your answering questions about your symptoms. Following that, a number of simple tests are performed to help pinpoint the nature of the problem.

What Can Cause Incontinence?

Incontinence occurs when normal anorectal function is disrupted. Damage to the anal sphincter, diseases of sensory and motor neurons of the pelvis, altered sensorium, and spinal cord injury may all result in leakage of stool due to inadequate sensation of the presence of stool in the rectum. Fecal soiling Opens in new window may occur in the elderly from constipation and overflow incontinence (involuntary loss of urine due to overdistension of the bladder).

The most common cause is obstetric trauma (60%). The second most common cause is iatrogenic injury to the anal sphincter muscles sustained during anorectal surgeries (approximately 16%). More and more often, incontinence is caused by injuries that occur after inserting foreign bodies to the rectum and after traffic injuries. Neurogenic incontinence is also a contributor. Table X shows some risk factors associated with incontinence.

Physiology and Normal Continence and Defecation

Incontinence is a common, disabling condition often associated with functional defecation disorders potentially open to nonsurgical treatments. It is considered to be primary a disorder associated with chronic constipation Opens in new window, with stool retention in 96% of children over the age of four years presenting with fecal incontinence.

In order to investigate continence and defecation disorders it is first necessary to understand these processes in a normal person. Unfortunately the literature only provides detailed studies of normal adults and so we are in the position of having to extrapolate these findings to children.

Stool frequency in Western communities decreases in the first years of life and then appears to plateau, but there is some evidence that this is not the case in developing communities for which there are no significant age-related differences.

Corazziari observed that bowel frequency was significantly higher in children younger than three years than those of 3 to 12 years but found no differences in total gastrointestinal transit time. Normal frequency in the older age groups was considered to be between 4 and 9 bowel actions per week. In young adults 5 to 12 bowel actions per week can be considered to be normal with males defecating significantly more frequently than females.

Continence is maintained by the physical resistance to the passage of feces moving from the rectosigmoid into the rectum and thence through the anal canal. Stool transfer into the rectum usually occurs as a result of colonic high-amplitude propagated contractions, which are more likely to occur after wakening and meals.

The rectum is generally collapsed before the arrival of feces, which then result in distension, rectal contraction, a sensation of urgency, reflex relaxation of the internal anal sphincter and semi-voluntary relaxations of pelvic floor muscles. If defecation does not occur, rectal contractions and the sense of urgency slowly subside with the rectum accommodating to continuing distension. Resistance to the movement of stool into the rectum allows its accumulation in the distal colon.

The movement of feces into the distal rectum from the sigmoid colon is impeded by its two lateral angulations and its spiral folds. Resistance to movement through the anorectum is provided by the sharp anteroposterior angulation and the anal sphincters. The anorectal angle is maintained by the striated pelvic muscles, mainly the puborectalis.

The anal sphincters form a high pressure zone consisting of two overlapping muscles: the internal anal sphincter (IAS) composed of smooth muscle, and the external anal sphincter (EAS) composed of striated muscle.

Tonic change in the IAS is entirely reflex whilst that in the EAS is under voluntary control. Contraction of the puborectalis sling in conjunction with contraction of the EAS is thought to assist the role of this sphincter. It does not appear to play as important a role in the maintenance of continence as the EAS.

The two sphincters can function independently of each other, depending on the need to accommodate fecal matter, ascertain the nature of the rectal contents, preserve continence or to defecate. At rest the sphincters maintain a high pressure zone which has an asymmetric profile with the highest pressures in the outermost sphincter area.

The asymmetry is largely maintained by contraction of the EAS which predominantly surrounds the distal anal canal and is submaximally tonically active under resting conditions. However, approximately 80 percent of the total sphincter tone is due to the activity of the IAS. Cyclical variations in resting pressure within the anal canal including spontaneous relaxations of the sphincter have been observed in adults and in children. There is a reduction in IAS tone, resting EAS activity and colonic motor activity during sleep in adults. There is some suggestion that the EAS undergoes periodic change in tonic activity.

With the arrival of sufficient feces in the rectal canal to cause it to distend to a threshold volume there is a reflex relaxation of the IAS accompanied by contraction of the EAS. This rectoanal inhibitory reflex (RAIR) is associated with an increase in rectal pressure due to rectal contraction and within one second a transient sensation.

The triggering of the RAIR appears to be dependent on the rate of rectal distension: slow continuous filling allows a greater volume to collect before the IAS relaxes. Further increases in rectal contents beyond this threshold produce a gradation of sensation from that of wind, to an urge to defecate, to the experience of pain. Following each increase in rectal contents and volume, the EAS recovers resting tone after the brief increase in activity. There is however a rebound increase in resting pressure of the IAS and the baseline rectal pressure increases for a period accompanied by an increase in rectal contractions.

The rectal contractions reduce earlier with slower rates of filling but accommodation of the rectal contents can occur longitudinally without the necessity of relaxation of the rectal wall. The increases in rectal contractions and axial pressures possibly tamp the stool into the proximal anal canal thereby increasing the defecatory urge.

As the volume increases the relaxation of the IAS increases in strength and duration until recovery no longer occurs and there is a sustained relaxation. Parallel to this the contraction of the EAS increases in strength and duration, maintaining continence. Prior to sustained relaxation of the IAS during the resting phases, Frenckner determined that the IAS is responsible for just over half the anal tone and is therefore still important in maintaining continence.

The progression from mild to acute urgency generally occurs with the attainment of sustained increase in rectal tone and dilatation of the IAS. The sense of urgency is likely due to activation of stretch receptors in the proximal rectum or sigmoid colon. There is disagreement about whether acute urgency and sustained relaxation of the IAS always occur together in normal children while in adults Sun et al. found no evidence for this.

There are significant differences between age groups in normal children in both the maximal tolerable rectal volume, and the threshold volume required to elicit rectal contractions (rectorectal reflex). The thresholds for these increased and decreased respectively with increasing age.

Although some component of the EAS response to the inhibitory reflex is spinal (as it is observed to an extent in paraplegic patients) depending on the level of the lesion it is susceptible to conscious control and therefore must be modulated by CNS involvement. During sleep there is no diminution of the IAS response but there is a significant reduction in the EAS component.

Very high levels of rectal distension can be associated with reflex abolition of both EAS and IAS activity causing a profound reduction in anal pressure resulting in automatic defecation. This has been noted in normal children and adults. This reflex is present in paraplegic patients with intact peripheral nerves and distal spinal reflexes so it is probably autonomous.

The sensory receptors are complex in that not only the presence but also the nature of rectal contents are perceived, and the sensation due to IAS relaxation is felt differently from that due to rectal distension. Receptors exist in the anal canal and may exist in the rectum and the muscles of the pelvic floor. There is disagreement about the origins of rectal sensation, whether mediated by receptors in the pelvic floor and not in the rectum, or whether as Sun and Loening-Baucke have postulated there are at least two types of rectal receptors: rapidly adapting mucosal receptors and slowly adapting mechanoreceptors in or on the rectal wall, as well as the possibility of some in the sigmoid colon.

Sun found that the duration of IAS relaxation and sensation in adults were not correlated although the former was always shorter than the latter. However, a strong association was found between the durations of EAS contraction and sensation. Transient sensation was not generally perceived if rectal contractions were not elicited and the EAS did not contract unless perception occurred.

Buser et al. found that some adults with fecal incontinence did experience sensation at a time when EAS contraction was absent, so postulated that the EAS contracts as the results of rather than the cause of sensation. Read and Read have suggested that the role of anal sensation receptors, as opposed to the rectal complex, may not be to preserve continence but to identify the rectal contents or signal the end of defecation. If this is the case then the RAIR allows testing of the rectal contents by these receptors, providing conscious information on which suitable actions may be taken. It has been suggested the spontaneous cyclical IAS relaxations fulfill the same purpose.

An alternative or supplementary mechanism for the identification of the physical nature of feces may be associated with the different rates of distension of the rectal wall accompanying the propulsion of material from the distal colon. As well as differences in RAIR thresholds, rapid rectal distension has been found to produce a different sensation from gradual distension to the same volume so that distinction between these may provide the discriminatory information.

However, whatever the order and origins of stimuli, it is obvious that once the rectal contents have reached the threshold for reflex relaxation of the IAS then at least subconscious awareness of stool in the rectum and immediate contraction of the EAS are essential for the preservation of continence. The ability to experience a sense of urgency before profound reflex anal dilatation occurs is likewise essential.

With an increase in intra-abdominal pressure there is a reflex compensatory increase in EAS activity to a level which provides an anal pressure in excess of the rectal pressure. This allows continence to be maintained when coughing, sneezing, blowing up balloons, laughing or any other activity which poses a threat by its effect on abdominal pressure. Voluntary squeezing or tightening up of the EAS to maintain continence involves no increase in intra-abdominal pressure.

Voluntary defecation takes place in three phases. Initially there is an increase in abdominal pressure and rectal pressure brought about by closure of the glottis, fixation of the diaphragm and contraction of abdominal, perianal and hamstring muscles combined with contraction of the puborectalis sling and both sphincters. Then the pelvic muscles relax allowing straightening of the rectoanal angle and of both sphincters.

The normal anorectal angle at rest is approximately 90^o and increases to 125^o during straining. At the same time strong colorectal contractions assist expulsion of the stool and the anal sphincters relax. Electrical activity in the EAS is greatly reduced at this stage. Schuster suggested that this relaxation takes place when the threshold for automatic defecation is reached. As defecation proceeds the rectal pressure gradually falls. The third stage involves the return to the original state after a rebound contraction of the anal sphincters.

It can be seen from the complex nature of continence and defecation that there are many opportunities for problems to occur both through physiological deficits and disordered processes.

Insufficient IAS or EAS resting tone, inadequate or delayed EAS response to the rectoanal inhibitory reflex, elevated or absent threshold of sensation from rectal distension and a blunted feeling of urgency have all been proposed as possible causes or at least contributors to fecal incontinence.

Inadequate colonic propulsion, failure of the IAS to relax, inappropriate contraction of the EAS and puborectalis, failure of the levators of lift the pelvic floor, luminal obstruction or an impairment in the central control of defecation may singly or in combination result in obstructed defecation.

Failure to relax the striated musculature of the pelvic floor during straining has been termed anismus and probably results in incomplete evacuation, fecal retention, chronic distension of the rectum, and possibly concomitant reduction in sensation leading to soiling or, at least, to its continuation. Attempts to identify pathophysiology which may be present in children with fecal incontinence have largely concentrated on studies of resting anorectal pressure and motility characteristics, sensation, the RAIR and the investigation of anismus.