Chronic constipation

Contributed by Dr Naila Arebi, consultant gastroenterologist, St Mark's Hospital, Harrow, and The London Clinic, London.

Section 1: Epidemiology and aetiology
Chronic constipation is a complex multi-symptom functional GI disorder.

Clinicians are often perplexed at its recalcitrant nature despite lifestyle modifications and laxative doses.

In contrast, acute constipation is short lasting and triggered by external factors such as certain drugs, travel and hospitalisation, or painful perianal conditions such as anal fissure.

The aetiology of acute constipation is usually self-evident and the condition resolves with short-term laxative therapy and removing the underlying triggering factors.

Chronic constipation is common and affects between 12 per cent and 19 per cent of the North American population.1,2 In Europe, prevalence ranges from 8 per cent to 26 per cent.3 Women are affected twice as commonly as men, and the condition affects all age groups.1,2

A compromised quality of life is reported with chronic constipation. In elderly patients it interferes with daily activities and well-being.4

In a small study, limited to females, severe idiopathic constipation was associated with significantly increased psychological and social morbidity, increased somatisation and less satisfaction with their sex life.5

Categorisation
Chronic constipation is often categorised as either primary or secondary. There are three primary pathophysiologic subtypes of chronic constipation, which are detailed below.

Slow-transit constipation is characterised by impaired phasic colonic motor activity resulting in decreased propulsion of residue. It is associated with underlying neuropathy or autonomic dysfunction.

Dyssynergic defaecation, or pelvic floor dysfunction, is due to the inability to co-ordinate abdominal, rectoanal and pelvic floor muscles. It may also be associated with impaired rectal sensation and is potentially an acquired behavioural disorder.

In normal transit constipation, patients exhibit normal colonic motility without evidence of pelvic floor dysfunction and insufficient criteria to meet the diagnosis of IBS.

The causes of secondary constipation are listed in the box.

Secondary causes of constipation
External factors

Drugs, e.g. opiates, anticholinergics, antidepressants, anticonvulsants

Neurological

  • Parkinson's disease
  • Multiple sclerosis
  • Spinal lesions
  • Damage to sacral parasympathetic nerves
  • Autonomic neuropathy

Psychological

  • Depression
  • Eating disorders
  • Obsession about 'inner cleanliness'

Endocrine/metabolic

  • Hypercalcaemia
  • Hypothyroidism
  • Porphyria

Section 2: Diagnosis
According to the Rome III criteria (see box) chronic constipation is defined as symptoms that have lasted for the past three months with an onset at least six months prior to diagnosis.

Because of symptom variation and inconsistent reports of decreased stool frequency, a broader definition for clinical management is acceptable.

Transit study showing constipation

This includes unsatisfactory defaecation characterised by infrequent stools, difficult stool passage (straining, incomplete evacuation, hard/lumpy stools, prolonged time to stool or requirement for manual manoeuvres), or both.

Symptoms should have been present for at least three of the previous 12 months in order to be considered chronic.

Investigations
The initial clinical evaluation of patients with chronic constipation should include a review of the patient's history and a physical examination.

This assessment should consider dietary intake of fibre, fluids and caffeine, plus lifestyle factors such as stress and lack of a toileting regime.

GI causes of constipation such as systemic sclerosis or megarectum may be evident. Associated symptoms of urinary incontinence suggest pelvic floor weakness or a previous history of difficult childbirth.

Psychological factors that may be contributing to symptoms should be identified: depression, anxiety and anorexia commonly present as constipation and should not be overlooked.

Most patients with chronic constipation do not require extensive diagnostic evaluation. Instead 'red flag' alarm signs or symptoms should prompt referral to a gastroenterologist (see box).

In primary care, in the absence of red flag symptoms, blood tests can be undertaken to exclude underlying metabolic causes, e.g. TFT and serum calcium. Diagnostic investigations in secondary care are typically geared towards identifying the underlying mechanism.6

'Red flag' alarm signs

  • New-onset constipation in an elderly patient.
  • Family history of colon cancer or inflammatory bowel disease.
  • Rectal bleeding.
  • Positive faecal occult blood test.
  • Unexplained anaemia.
  • Weight loss of [s40] 4.5kg.

Shape study
Slow transit constipation can be diagnosed by various tests. The easiest and most readily available test is a colonic marker study.

In our practice this consists of asking patients to swallow capsules on three consecutive days. Each capsule contains 20 radio-opaque markers of different shapes.

Defaecatory proctogram
Defaecatory proctogram is a dynamic study of the rectum and pelvic floor. A barium enema is retained until fluoroscopy of the evacuatory process commences with defaecation of the barium.

This test assesses the ability to empty the rectum, the rate of emptying and movement of the pelvic floor.

Anorectal manometry
Anorectal manometry involves insertion of a pressure sensitive catheter into the anal canal. Measurement of resting and squeeze pressure can give an indication of anismus or dyssenergia.

Manometery is also useful in suspected cases of Hirschsprung's disease (HD). Absent relaxation of the anal sphincter in response to rapid balloon distension is a hallmark of HD, although is not diagnostic.

Additional tests of rectal sensation can also be undertaken. Slow balloon distension gives an indication of sensory, urge and pain thresholds, and electrical stimulation enables detection of neurological dysfunction.

Balloon expulsion test
In the balloon expulsion test a rectal balloon containing 50ml of water is inserted into the rectum and the patient instructed to expel the balloon to mimic defaecation. Examination during expulsion may also show evidence of abnormal or absent pelvic floor descent.

Rome III criteria for constipation
All three of the following criteria must be met:

1. At least two of the following:

  • Hard or lumpy stool in at least 25% of defaecations;
  • Straining during at least 25% of defaecations;
  • Sensation of incomplete evacuation in at least 25% of defaecations;
  • Sensation of anorectal obstruction or blockage for at least 25% of defaecations;
  • Manual manoeuvres (e.g. digital evacuation or pelvic-floor support) to facilitate at least 25% of defaecations;
  • Fewer than three defaecations per week.

2. Loose stools rarely present without the use of laxatives.

3. Insufficient criteria for IBS.

Section 3: Managing the condition
Therapy for chronic constipation involves multiple concomitant approaches.

These include lifestyle and dietary advice, laxatives, biofeedback therapy, irrigation devices, psychological therapies and, rarely, surgery. This condition is best managed within a multidisciplinary team setting.

Reassurance
Reassurance that the condition is common may prompt patients to accept their condition and reduces the feeling that they are 'abnormal'.

Reassurance should also address myths about constipation, the most common being that it may predispose to cancer or that toxins are accumulating in the body.

Lifestyle/measures
Assessment of fibre intake, response to call to stool and adequate physical activity is recommended for a healthy lifestyle.

Laxatives
Laxatives are classified into four main groups according to their mode of action: bulking agents, stool softeners, stimulant laxatives and osmotic laxatives.

Bulking agents may exacerbate bloating. Stool softeners such as paraffin are not often used for chronic constipation; osmotic and stimulant groups form the mainstay of therapy.

There are two groups of osmotic laxatives: fast-acting magnesium salts, which work within two to six hours, and agents with a slower onset of action such as lactulose and macrogols.

Stimulant laxatives are useful in neurological conditions, immobility and cases of slow transit constipation. Senna and biscodyl are commonly used. Co-danthramer has been withdrawn except for terminal care.

For patients with a persistent urge to defaecate, suppositories should be considered.

Biofeedback therapy
Behavioural treatment, specifically biofeedback, ameliorates constipation symptoms and is frequently used as alternative therapy for patients with symptoms unresponsive to lifestyle modification and needing large amounts of laxatives.7,8

The principle is to make patients aware of the body's biological processes. For constipation, this consists of education on the physiology of defaecation, showing the effect of posturing and teaching patients how to co-ordinate defaecatory muscles effectively. Specialist colorectal centres, like St Mark's Hospital, usually provide these services.

Irrigation devices
Occasionally, where laxatives have failed or where this is an underlying neurological condition rectal irrigation, with adoption of a regular bowel regimen, may be acceptable to patients.

Psychological assessment
Psychological factors, particularly anxiety, depression and social dysfunction, predispose to constipation.

These disorders, as well as somatisation, obsessive-compulsive disorders or the need for self-control, have been associated with chronic constipation.

Patients with eating disorders may manifest with constipation as the presenting symptom. A low BMI or amenorrhoea in conjunction with constipation should raise the possibility of anorexia.

Psychological factors are believed to slow down colonic transit by inhibiting autonomic outflow to the colon.

Specific features from the history may indicate psychological morbidity as a driver for constipation in women.

These include a history of physical or sexual abuse, separation from or death of parent or partner, and emotional problems such as difficulty in forming and maintaining intimate relationships.

Once these parameters have been identified patients should be offered a psychological approach to further investigate or treat their constipation.

Some are reluctant to engage in a psychological therapy when offered in isolation but may find it acceptable when combined with biofeedback.

Identification of psychological morbidity with constipation should prompt referral to a specialist centre where a holistic approach to care can easily be implemented.

Surgery
The results of surgical outcomes are inconclusive. Surgery was often undertaken in the 70s and 80s. However, this is not so common nowadays. The options are a colostomy, colectomy with ileorectal anastomosis or colectomy with ileostomy.

Sacral nerve stimulation

Implantation of an electrode in approximation to a sacral nerve, usually S2 or S3, as it exits from the sacral foramen is approved by NICE for faecal incontinence.

Preliminary reports suggest it may also be effective for constipation. However, it is still not licensed for this indication.

Management algorithm
Patients should be assessed for obvious underlying causes. If assessment is negative then a laxative trial may be sufficient to control symptoms. Suppositories may be considered for patients with a present urge.

When there is evidence of pelvic floor dysfunction or no improvement with laxatives then referral is warranted.

We have developed a streamlined service at St Mark's for the efficient management of chronic constipation. Patients undergo physiological testing on the same day as an assessment by a biofeedback specialist nurse. They receive four or five biofeedback sessions.

Non-responders or new symptoms will be discussed with a consultant gastroenterologist and psychiatrist at weekly multidisciplinary team meetings so that appropriate management is instituted.

Section 4: Prognosis
Prognosis depends on the underlying predisposing factors and any psychological morbidity.

Slow transit constipation, dyskinesia of the pelvic floor musculature or sphincter mechanism and outlet obstruction may be managed via biofeedback therapy with response rates of up to 75 per cent.8

Patients who are dependent on increasing doses of self-prescribed laxatives are perhaps the most difficult to treat. Most patients can be treated with a combination of laxatives. However, the need for increasing dosages and the intermittent use of other agents becomes problematic.

Some patients can be helped by biofeedback therapy and occasionally rectal irrigation. In rare situations total colectomy may be performed.

Patients with outlet obstruction may respond well to surgical correction and have a good prognosis after a careful preoperative workup, including physical and psychological assessment.

New therapies
Tegaserod, a 5-HT4 receptor agonist, accelerates colonic transit and has been evaluated in clinical trials. However, reports of cardiac toxicity led to early withdrawal.

Newer agents such as lubiprostone, which selectively activates intestinal type-2 chloride channels on the apical intestinal membrane, increase passive fluid secretion into the intestinal lumen. This drug has been FDA approved but is not yet available in the UK.

Intestinal chloride, bicarbonate and water secretion can be increased by production of cGMP in colonic cells resulting in accelerated transit. A potent guanylate cyclase-C agonist, linaclotide, has been shown to improve bowel movement.

Two recently FDA-approved opioid antagonists, alvimopan and methylnaltrexone, modulate gut function. Studies on patients with opioid-induced constipation are yielding promising results.

Lastly, probiotic preparations have been shown to increase colonic transit, although the exact mechanism is unknown.

References

1. Higgins P, Johanson J. Epidemiology of constipation in North America: a systematic review. Am J Gastroenterol 2004; 99: 750-9.

2. Pare P, Ferrazzi S, Thompson W, Irvine E, Rance L. An epidemiological survey of constipation in Canada: definitions, rates, demographics, and predictors of health care seeking. Am J Gastroenterol 2001; 96: 3,130-7.

3. Peppas G, Alexiou VG, Mourtzoukou E, Falagas M. Epidemiology of constipation in Europe and Oceania: a systematic review. BMC Gastroenterology 2008; 8: 5.

4. O'Keefe E A, J Gerontol. Bowel disorders impair functional status and quality of life in the elderly: a population-based study. A Biol Sci Med 1995; 50: M184-M189

5. Mason H J, Serrano-Ikkos E, Kamm M. Psychological morbidity in women with idiopathic constipation. Am J Gastroenterol 2000; 95: 2,852-7.

6. Rao S, Ozturk R, Laine L. Clinical utility of diagnostic tests for constipation in adults: a systematic review. Am J Gastroenterol 2005; 100: 1,605-15.

7. Mason H, Serrano-Ikkos E, Kamm M. Psychological state and quality of life in patients having behavioral treatment (biofeedback) for intractable constipation. Am J Gastroenterol 2002; 97: 3,154-9.

8. Chiotakakou-Faliakou E, Kamm M, Roy A, Storrie J, Turner I. Biofeedback provides long-term benefit for patients with intractable, slow and normal transit constipation. Gut 1998; 42: 517-21.

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