Faecal Incontinence and Constipation in the Older Person
- Requires relaxation of the anal sphincters (Recto-anal inhibitory reflex)
- Varies with stool consistency
- Often follows a gastrocolic reflex (whole gut mass movement following eating and / or exercise)
- Normal frequency varies between twice per week to 3 times per day
A number of mechanisms contribute to the maintenance of anal continence.
Constipation and faecal incontinence are very common in older people especially in the frail and disabled. There are a number of age related changes which increase the risk of faecal incontinence in old age (background factors) with other specific factors that lead to loss of continence.
External anal sphincter weakness
Squeeze pressures fall with age and probably also with immobility but this doesn't necessarily need to lead to loss of bowel control.
Pudendal neuropathy will often be present due to old childbirth stretch injury (especially if forceps were used) or chronic straining at stool.
Loss of anal sensation
Anal sensation is impaired in older people and in incontinent patients but does not necessarily result in faecal incontinence even when totally absent.
This may contribute towards faecal incontinence due to either: Physical factors i.e. loss of gastrocolic reflex; or dependency upon others especially if urgency of defecation.
Faecal loading especially with soft faeces
Most common cause of faecal incontinence in the elderly
Faecal soiling in faecally loaded patients is more common when soft stool is present and leakage usually occurs before a call to stool is experienced
Usually associated with loss of anorectal angle
How do you define Constipation?
Infrequent bowel movements
Straining to pass stool
The faecally loaded incontinent patient, however, may leak up to 10 times per day, doesn't have to strain and has very soft stools.
What does the term faecal impaction mean?
Rectum and colon full of hard faeces but less than 10% of faecally loaded patients have a rectum loaded with hard stool.
Constipation can be the presenting symptom of colonic disease and may require investigation.
'Idiopathic Constipation' can be classified as either slow transit or normal transit constipation.
Slow transit (usually due to lack of colonic propulsion) predominates among the frail elderly. Their whole gut transit times often exceed 14 days (normal < 5 days). Some these patients develop a megarectum. Abdominal radiographs will often demonstrate extensive faecal loading throughout the colon.
Normal transit patients tend to experience major problems with the process of defecation e.g. inappropriate sphincter contraction on attempted defecation or obstructed defecation due to rectocele or intussussception. Defecating proctography may help in diagnosis.
Loss of rectal awareness of the call to stool may also contribute towards the development of constipation.
Internal sphincter weakness with low anal resting tone
- Anal resting tone does not exhibit ageing effects
- Low resting pressures are found in incontinent patients of all ages. One possible cause of this is physical disruption of the sphincter. This can be demonstrated in special centres by use of anal ultrasound.
- In some incontinent patients the anus gapes open. It cannot therefore delay the passage of liquids but it can still delay the passage of solid material. Continence may be restored therefore by changing stool consistency.
Clostridium difficile is now a particular problem among hospital inpatients. The profuse diarrhoea and malaise tend to overwhelm continence mechanisms. Prevention measures should include adoption of strict antibiotic policies and handwashing by all staff before and after contact with patients.
Loss of cognitive awareness
Unconsciousness. The most basic requirement for control of bowel evacuation is for a person to be awake. Loss of this will inevitably lead to faecal leakage as voluntary control is not possible.
Dementia. Many patients with advanced dementia are incontinent of faeces usually due to severe mental confusion and loss of awareness of the 'call to stool'.
Behavioural. Many patients with severe behavioural problems defecate in inappropriate places e.g.. in lounge of residential home. This is presumably due to severe frontal lobe damage or degeneration and proves very difficult to manage; it may also be associated with faecal smearing and / or coprophagia.
History and physical examination
The history needs to include enquiry into
• Bowel habit past and present including awareness of call to stool, defecation, stool consistency and about episodes of leakage.
• Diet enquiry should ask specifically about fibre content.
• Laxative use
Physical examination to include
· Abdominal examination for presence of palpable faecal mass(es).
· Anorectal examination looking for evidence of perineal descent, gaping anus, rectal prolapse, perianal scarring and / or soiling.
· Digital examination to assess anal resting tone and squeeze and to determine whether there any abnormal rectal lesions or faecal loading of the rectum. If the rectum is loaded then determine the stool consistency.
· Cognitive assessment
Bowel Investigations will occasionally be indicated to exclude significant bowel pathology. Not all incontinent patients will necessarily need them. If requesting investigations such as Barium Enema in someone with faecal incontinence remember that they are likely to experience profuse diarrhoea and incontinence during the bowel clearance in preparation for the test and there is a high chance that they will not retain the barium. You may put them through the test without obtaining any useful clinical information.
How do you help someone with bowel problems?
The management plan that is proposed below for faecal incontinence and constipation is goal orientated. (The aim should also be to educate mentally competent patients about how their bowels work, how to regain control and how to respond to changes in their bowel habit as the problems are often ongoing).
The 2 main aims in bowel management in old age are:
1. to produce stools of the ideal consistency which are not too hard nor too soft;
2. bowel emptying to occur at a predictable time.
The ideal stool has been christened the 'Goldilocks stool' because it is not too hard and not too soft, but "just right". Most old people with faecal incontinence, however, produce stools which resemble Goldilocks porridge i.e. soft and gooey. That would not be "just right" as that is precisely the type of stool which leaks easily and is very messy to clean up.
Aim No 1 is usually the initial target for patients seen in a community setting whereas aim No 2 is usually the initial target for patients in hospital or care home settings
Treatment aim No. 1 : To produce stools of the ideal consistency which are not too hard nor too soft
If stools are too hard the aim should be to soften them to produce a firm stool which is easy to pass when defecation is attempted.
Increase dietary fibre intake? 'Healthy eating' is widely promoted and appears to be desirable for otherwise healthy people to reduce their risk of diverticular disease and other colorectal abnormalities including constipation. Fibre is effective at softening stool, increasing its bulk and stimulating defecation.
This, however, is not usually desirable as a treatment for frail elderly with constipation or anyone with faecal incontinence as the high fibre intake adds to the existing colonic faecal loading and increases the risk of faecal incontinence. Fibre also causes flatulence.
An alternative is to soften hard stool with an osmotic laxative e.g. Lactulose. Lactulose exerts its osmotic effect only in the small bowel. It increases faecal weight, volume and water content as well as bowel movements and usually acts within two days. Alternatives include Docusate which is a faecal softener but a poor laxative. Magnesium Sulphate is a potent osmotic laxative to reserve for some resistant cases.
If stools are too soft (or diarrhoea)
Diarrhoea is often associated with faecal incontinence. Whilst the cause is sought, use of antidiarrhoeal agents (constipating drugs) can considerably improve patients symptoms. The most popular drug in this class is loperamide which is effective in altering stool consistency from soft to firm and if too much is used to hard. It may prevent faecal incontinence by mechanisms other than by just changing stool consistency - loperamide has been shown to influence internal sphincter function. Alternative agents in this class include codeine phosphate.
The main challenge when using loperamide to alter the stool consistency for patients with soft stools is to get the dose right as too much induces severe constipation. The following starting doses are suggested:
* Soft stool - 0.5 mg / day of the syrup preparation titrated slowly up or down depending on result;
* Liquid stool - 2 - 4 mg / day but may require much higher doses initially until stool becomes firmer.
Maintenance doses of loperamide tend to fluctuate depending upon stool consistency in individual patients. Some patients require very little i.e. 0.5 mg once per week whereas others require large doses. A patient education programme leading to them modifying their own dose of loperamide to achieve the goal of the ideal stool consistency appears to be the most effective regimen to follow.
Treatment Aim No.2 : Bowel emptying to occur at a predictable time
This is achieved in normal circumstances by defecating in an appropriate place by consciously responding to the call to stool.
The method used to assist patients who are experiencing problems either opening their bowels or controlling when their bowels open depends on a number of factors which include the presence of faecal incontinence, discomfort due to a loaded colon and / or rectum which the patient cannot empty and the patient's mental state.
In the presence of faecal incontinence the initial aim of treatment should be to empty the rectum and colon within a few days to prevent faecal soiling. The preferred treatment is to empty the rectum by administering an enema or suppository each day until the faecal mass is cleared.
Usually when suppositories are used to stimulate defecation glycerine suppositories are used but more potent stimulation of defecation may be obtained by use of bisacodyl. It is now recognised that suppositories are best inserted blunt end first as they are easier to insert and better retained than the traditional sharp end first method.
Microenemas are now the preferred enema principally because they are effective and easy to administer and are free of the adverse publicity associated with phosphate enemas.
Occasionally suppositories and / or enemas are ineffective at inducing defecation in either the acute or chronic situation when manual removal of faeces may be required especially if the stool is very hard. For patients with an atonic rectum this is often the only treatment available. This problem is particularly prevalent among patients with severe spinal cord lesions e.g. multiple sclerosis, traumatic cord lesions, in whom the parasympathetic supply to the rectum is deficient.
In patients who are faecally loaded with soft or formed stool but not incontinent or in discomfort the preferred treatment is a stimulant laxative given orally. The most commonly used are senna (Senokot), sodium picosulphate and bisacodyl, which act directly on the myenteric plexus. They should be given at night as they take 10 - 14 hours to reach the colon where they exert their effect which ideally should occur during the day rather than during the night. Long term use of stimulant laxatives should be avoided, if possible, especially in younger patients as they may cause myenteric plexus degeneration.
Occasionally a combined osmotic and stimulant laxative e.g.. codanthromer, codanthrusate is required when softening stool has not induced defecation or in patients with drug induced constipation e.g.. secondary to opiates.
Long term bowel management
Maintaining a regular pattern of bowel emptying
In approximately 50% of the elderly patients who are constipated during hospitalisation for an acute illness, the problem resolves with the treatment of their underlying illness. Other patients, however, have a continuing tendency to 'constipation'. Their whole gut transit time is not necessarily reduced by the clearance of the faecal loading. Laxatives are the main treatment for these patients but some require regular emptying of their bowel from below using either enemas or suppositories.
Treatment of the faecally incontinent demented patient
Incontinence in these patients is usually secondary to faecal loading, which should be cleared as above. A regimen of planned defecation should be implemented by the use of an enema 1 - 3 times per week if there is a continuing tendency to faecal incontinence and / or constipation. A constipating drug may be needed to prevent leakage between enemas. Poor compliance with treatment tends to limit its success especially in patients with severe behavioural problems. Strategies that may help these patients include the administration once weekly of a potent stimulant laxative e.g. sodium picosulphate (initial dose 5mg).
Treatment of anorectal incontinence i.e. weak anal sphincters.
The principles of treatment are similar to those described above. Maintaining a firm stool will help the majority of cases. Moderate success (approximately 60%) has been reported with surgical repairs in young and middle aged incontinent patients but its use cannot be recommended for the elderly as the problems tends to be multifactorial.
Outcome of treatment for faecal incontinence
In the vast majority of cases the simple measures described above are effective. The outcome of treatment is however influenced by the presence of other problems e.g.. dementia especially when there are behavioural problems present. The main anorectal factor that influences outcome is rectal prolapse as the ideal stool for a prolapse patient is soft rather than firm.
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