Country	Population	Prevalence
Holland	Women >60 y	4.2% to 16.9% with rising age
France	All >45 y	11%, 6% to faeces, 60% women
UK	Community service	1.9%
USA	Market mailing	7% soiling, 0.7% to faeces
USA	Wisconsin households	2.2%, 63% women
USA	Wisconsin nursing homes	47%
New Zealand	>65 y	3.1%
Australia	Household survey	6.8% men
Australia	Household survey	10.9% women >15 y
Australia	Postal survey	Liquid incontinence 9%
Australia	Random selection from electoral roll (subjects ≥18 y)	Solid incontinence 2%

Based on Continence Foundation of Australia. Incontinence: some key statistics and quotes clarified. Online.

Available: www.contfound.org.au/pdf/Keystatsquotsmay03.pdf.

Incontinence is such an embarrassing condition that few people speak of it. As a result, its true prevalence is believed to be higher than that reported.

AETIOLOGY

Table 19.2 lists the possible causes of faecal incontinence. Looser stool consistency is an important precipitating factor in those predisposed to faecal incontenance by anorectal abnormalities.

TABLE 19.2 Classification of the aetiology of faecal incontinence

Altered stool consistency—diarrhoeal states

• Irritable bowel syndrome

• Inflammatory bowel disease

• Infectious diarrhoea

• Laxative abuse

• Malabsorption syndrome

• Short-gut syndrome

• Radiation enteritis

Inadequate reservoir capacity or compliance

• Inflammatory bowel disease

• Absent rectal reservoir

– Sphincter-saving operations

• Low anterior resection

• Coloanal anastomosis

• Ileorectal anastomosis

• Ileoanal reservoir

• Rectal ischaemia

• Collagen vascular disease

• Extrinsic rectal compression

Inadequate rectal sensation

• Overflow incontinence

Abnormal sphincter mechanism or pelvic floor

• Congenital abnormalities

Obstetric injuries

During vaginal delivery, perineal tears are common and complications of vaginal delivery are among the most common causes of incontinence seen by the surgeon. In fact one-third of vaginal deliveries lead to some form of sphincter injury. However, the majority of patients present with incontinence at a later stage when the muscles are unable to compensate.

The risk factors of vaginal delivery include primigravidas, babies with high birth weight and instrumental delivery, e.g. forceps delivery. The tear is not prevented by episiotomy. It is reported that 70% of women who experience a third or fourth-degree tear will report incontinence to flatus.

Another indirect mechanism of incontinence attributed to childbirth is stretch injury to the pudendal nerve during labour. This injury may then lead to denervation of the external sphincter, the internal sphincter and puborectalis muscle. The denervation injury may develop decades after the injury.

Ageing

A common form of anal incontinence is that associated with old age and general debilitation. It is usually a neurogenic incontinence.

Previous operations

Trauma

Traumatic injury to sphincters may occur during an accident. Serious forms of injury may require a temporary stoma. The anal sphincter is then re-assessed and appropriately treated prior to closure of the stoma at a later stage.

Primary disease

Diarrhoea from any cause, chronic inflammation in the rectum or carcinoma of the anal canal may present with incontinence. This obviously has to be treated according to the cause of the problem.

Radiotherapy

It has been shown that radiotherapy can increase the risk of anal incontinence. This is important as chemoradiation is commonly used as a pre-operative and post-operative treatment for rectal cancer. However, the incidence of incontinence is still quite low. Radiation proctitis can also lead to bleeding as well as incontinence.

Neurogenic causes

This includes myelomeningocele, demyelinating disease and diabetic patients with autonomic neuropathy.

Idiopathic incontinence

A large number of patients do not have any evidence of anorectal abnormality. However, they usually have problems with their pudendal nerve. It is probably related to stretching of the nerve during vaginal delivery or straining for any reason.

Congenital abnormalities

Various operations have been designed for treating an imperforate anus and they usually result in various extent of incontinence.

Miscellaneous causes

Overflow incontinence secondary to faecal impaction or pelvic floor disorders such as the solitary rectal ulcer syndrome (ulceration secondary to rectal prolapse or a non-relaxing puborectalis muscle) may be associated with varying degrees of incontinence.

HISTORY

A detailed history is absolutely necessary in the assessment of any pathological condition, paying particular attention to the characteristic cause and extent of the incontinence. It is important to determine the nature of incontinence—whether it is incontinence to solid, liquid or flatus—and to determine the frequency of the incontinence and the necessity to wear a protective pad. Other associated symptoms such as urgency need to be determined as well as social limitation as a result of the incontinence.

Direct questioning is necessary on the history of vaginal delivery and complications. The patient should also be asked about associated conditions such as urinary incontinence, rectal prolapse, diabetes mellitus, medications, radiation treatment or any congenital abnormalities. It is also important to determine whether the patient has had a previous anorectal operation, low colon anastomosis or trauma to the anorectal area.

There are many continence scoring systems available in the literature. Most of them are useful for research purposes but are not practical for day-to-day use. The St Mark’s scoring system is listed in Table 19.3. A clue to the severity of incontinence is determining the frequency of the incontinence, the necessity to wear a protective pad and the effect on social function.

TABLE 19.3 St Mark’s continence scoring system

Symptom severity	Score
Incontinence to solid stool
Never	0
Less than once per month	1
Less than once per week	2
Most days	3
Incontinence to liquid stool
Never	0
Less than once per month	1
Less than once per week	2
Most days	3
Incontinence to flatus
Never	0
Less than once per month	1
Less than once per week	2
Most days	3
Ability to withhold defecation more than 15 min
Yes	0
No	1

Difficulty cleaning after evacuation No 0 Yes 1 Soiling None 0 Minor 1 Major 2

0 = fully continent; 13 = regularly completely incontinent to all rectal contents.

PHYSICAL EXAMINATION

• The underpants and the perineum should be inspected for staining by stool, mucus or pus.

• On inspection of the perineum, a large patulous anus is suggestive of possible rectal prolapse. Scar from previous operations or episiotomies should also be carefully noted.

• The patient should be asked to strain. Perineal descent or mucosal/full thickness rectal prolapse may become obvious on straining.

• Per rectum examination:

– Palpate for any sphincter defect

– Palpation with the index finger can also detect any keyhole deformity of the anal canal, which may lead to soiling

– Any tumour or the presence of blood can also be determined from the finger examination

– Assess the resting and squeeze tones of the anal muscle. The tone is assessed both at rest (resting tone) and when the patient is asked to squeeze (squeeze tone). The resting tone assesses the function of the internal anal sphincter and the squeeze tone assesses the integrity of the external anal sphincter.

• Rigid sigmoidoscopy may reveal any internal rectal prolapse, inflammatory process or neoplasm contributing to the patient’s complaint.

INVESTIGATIONS

Flexible sigmoidoscopy

It is important to exclude rectal tumour or inflammation in the rectum causing incontinence. This can be detected and biopsy taken with a flexible sigmoidoscopy.

Endoanal ultrasound

This is a procedure whereby an ultrasound probe is inserted into the anal canal for assessment of the integrity of the anal sphincters. It can detect a sphincter defect secondary to childbirth, trauma or previous operations. A sphincter defect usually implies that the problem is amenable to surgery.

Anorectal physiology

Anal manometry

A catheter is inserted into the rectum and the resting and squeeze pressure can be measured. The catheter is connected up to four to eight channels of fluids under a pressurised system. When the patient is at rest, the resting pressure is measured. The patient is then asked to squeeze on the catheter and the squeeze pressure is measured. The resting pressure is a measure of the function of the internal anal sphincter whereas the squeeze pressure is a measure of the function of the external anal sphincter. The rectoanal inhibitory reflex is measured in order to exclude the possibility of Hirschsprung’s disease.

Pudendal nerve terminal motor latency

This procedure measures the conduction time for the pudendal nerve on each side. The pudendal nerve is the nerve supply to anal muscles. If the conduction time is prolonged, which is normally less than 2 ms, it indicates pudendal nerve neuropathy. This is usually performed with a finger electrode whereby electrical pulses are sent along the electrode to stimulate the pudendal nerve on each side. The conduction time is then recorded and measured once sizeable contraction of anal muscles occurs.

TREATMENT

Treatment of incontinence involves non-operative and operative procedures (see Figure 19.1).

FIGURE 19.1 Diagnosis and treatment of faecal incontinence.

Non-operative procedures

Medical treatment

Dietary changes and perineal exercises are often recommended for patients with faecal incontinence. There are also various antidiarrhoeal drugs that are available in the management of patients with incontinence. Drugs such as loperamide or diphenoxylate are used, which inhibit intestinal motility by a direct effect on the circular and longitudinal muscles of the intestinal wall. The majority of causes of faecal incontinence can be managed with medical treatment.

Biofeedback training

Biofeedback training involves at least three components: exercise of the external sphincter muscle, training in the discrimination of rectal sensation and training in synchrony of the internal and external sphincter responses during rectal distension. Selection of patients is very important for biofeedback training to be successful. The patients have to be well motivated and alert for the three-phase instructions on voluntary control mechanisms.

The method involves placing a balloon in the rectum and connecting pressure transducers to a graph to give the patient visual feedback corresponding to their sphincter responses to command. Initially, a large rectal balloon is used and the volume of distension of the balloon is gradually reduced until the patient can relax the external anal sphincter in response to a small distension. Finally, the visual feedback is eliminated and the patient is checked by a trained observer to see if they can respond to rectal sensation alone. This method improves contraction of the pelvic floor muscles, thereby increasing tone and reducing the chance of incontinence.

Operative procedures

It is important to bear in mind that the majority of patients with faecal incontinence can be treated with conservative management, i.e. diet change, medication, biofeedback training and continence advice. Only a minority of patients require operative intervention.

Overlapping sphincteroplasty

This operation is indicated for patients with a definite sphincter defect. The operation involves dividing the scar tissue and overlapping the sphincter complex (internal and external anal sphincters). The short-term results are good in about 80%–90% of patients. However, the results are not as good on long-term follow-up.

Postanal repair

This operation is now seldom performed and its success rate is said to be about 50%.

Graciloplasty

This operation involves using the gracilis muscle in the thigh to wrap around the anal canal and act as a new sphincter. It also involves stimulation of the gracilis muscle with a pacemaker via leads to the neurovascular bundle of the muscle. The gracilis muscle is constantly stimulated by the pacemaker to close the anus in the resting state. During defecation, the pacemaker can then be switched off with a remote control to relax the gracilis muscle so that the defecation process can occur. This operation carries a significant morbidity rate and almost 50% of patients require a stoma in the long term.

Artificial sphincter

This operation involves the insertion of an artificial sphincter around the anus. It is not often performed because of the high risk of infection of the prosthesis.

PTQ™ implant

PTQ™ implants are injectable tissue-bulking agents used for the treatment of faecal incontinence. They are made of small-refined solid particles of implantable silicone in a water-based carrier gel. It is injected into the sphincter defect or the intersphincteric space. The implant allows for the ingrowth of collagen tissues making it stay at the injected location permanently. It can be used for a small sphincter defect to fill the gap or for a weak thin internal anal sphincter to increase bulk in the anal canal.

The increase in bulk can then reduce the luminal size of the anal canal, thus improving incontinence. It is best injected under ultrasound control so that the placement of the implant is accurate.

Sacral nerve stimulation

This operation is indicated for patients who fail conservative management of faecal incontinence. It is divided into two stages. The first stage involves testing the effect of stimulating the pelvic nerve—mainly S3. This is performed via insertion of lead wires into the S3 foramen to stimulate the S3 nerve. The wire is then connected to an external temporary pacemaker. The patient carries the pacemaker around for 7–10 days during this trial period to see whether the stimulation improves their continence. If continence does not improve over the trial period, the wires are then removed. If the continence improves, a permanent pacemaker is then inserted under the skin in either the buttock or the anterior abdominal wall. This stimulation of nerve leads to increase of anal tone and therefore improves continence. The result from the operation showed that 85% of patients have significant improvement—85% of patients have more than 50% reduction in incontinent episodes.

SUMMARY

Faecal incontinence is the involuntary passage of stools through the anus. The prevalence rates of faecal incontinence in the world vary from 0.7%–11%. Obstetric and operative injuries account for most cases of incontinence. Incontinence is common with ageing and debilitation.

A detailed history and clinical examination is important with special emphasis on vaginal delivery and any complications (Figure 19.1). On per rectum examination, assess resting tone and squeeze tone. Investigations include flexible sigmoidoscopy, which is mandatory, endoanal ultrasound, anal manometry and pudendal nerve terminal motor latency.

The mainstays of medical treatment are diet, perineal exercises and anti-diarrhoeal drugs. There have been good results with biofeedback training. Operative procedures include overlapping sphincteroplasty and sacral nerve stimulation.